Asp.NetCoreWebApi - RESTful Api

目录

• 参考文章
• REST
• 常用http动词
• WebApi 在 Asp.NetCore 中的实现
  • 创建WebApi项目.
  • 集成Entity Framework Core操作Mysql
    • 安装相关的包(为Xxxx.Infrastructure项目安装)
    • 建立Entity和Context
    • ConfigureService中注入EF服务
    • 迁移数据库
    • 迁移数据库失败, 提示 Unable to create an object of type 'Context'. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728
    • 数据库迁移结果
    • 3.2.6. 为数据库创建种子数据
• 支持https
• 支持HSTS
• 使用SerilLog
  • 安装nuget包
  • 添加代码
  • 自行测试
• Asp.NetCore配置文件
  • 默认配置文件
  • 获得配置
• 自定义一个异常处理,ExceptionHandler
  • 弄一个类,写一个扩展方法处理异常
  • 在Configuration中使用扩展方法
• 实现数据接口类(Resource),使用AutoMapper在Resource和Entity中映射
  • 9.1. 为Entity类创建对应的Resource类
  • 使用 AutoMapper
• 使用FluentValidation
  • 安装Nuget包
  • 为每一个Resource配置验证器
• 实现Http Get(翻页,过滤,排序)
  • 资源命名
    • 资源应该使用名词,例
    • 资源命名层次结构
  • 内容协商
• 翻页
  • 构造翻页请求参数类
  • Repository实现支持翻页请求参数的方法
  • 搜索(过滤)
  • 排序
    • >排序思路
• 资源塑形(Resource shaping)
• HATEOAS
  • 创建供应商特定媒体类型
    • 判断Media Type类型
• Post添加资源
  • 安全性和幂等性
  • 代码实现
• Delete
• PUT & PATCH
  • PUT 整体更新
  • PATCH
• Http常用方法总结

参考文章

• ASP.NET Core Web API 开发-RESTful API实现
• 理解HTTP幂等性
• 某站微软Mvp杨旭的Asp.NetCore WebApi的视频

---

REST

REST : 具象状态传输(Representational State Transfer,简称REST),是Roy Thomas Fielding博士于2000年在他的博士论文 "Architectural Styles and the Design of Network-based Software Architectures" 中提出来的一种万维网软件架构风格。
目前在三种主流的Web服务实现方案中，因为REST模式与复杂的SOAP和XML-RPC相比更加简洁，越来越多的web服务开始采用REST风格设计和实现。例如，Amazon.com提供接近REST风格的Web服务执行图书查询；

符合REST设计风格的Web API称为RESTful API。它从以下三个方面资源进行定义：

• 直观简短的资源地址：URI，比如：http://example.com/resources/ .
• 传输的资源：Web服务接受与返回的互联网媒体类型，比如：JSON，XML，YAML等...
• 对资源的操作：Web服务在该资源上所支持的一系列请求方法（比如：POST，GET，PUT或DELETE）.

PUT和DELETE方法是幂等方法.GET方法是安全方法（不会对服务器端有修改，因此当然也是幂等的）.

ps 关于幂等方法 :
看这篇 理解HTTP幂等性.
简单说,客户端多次请求服务端返回的结果都相同,那么就说这个操作是幂等的.(个人理解,详细的看上面给的文章)

不像基于SOAP的Web服务，RESTful Web服务并没有“正式”的标准。这是因为REST是一种架构，而SOAP只是一个协议。虽然REST不是一个标准，但大部分RESTful Web服务实现会使用HTTP、URI、JSON和XML等各种标准。

常用http动词

括号中是相应的SQL命令.

• GET(SELECT) : 从服务器取出资源(一项或多项).
• POST(CREATE) : 在服务器新建一个资源.
• PUT(UPDATE) : 在服务器更新资源(客户端提供改变后的完整资源).
• PATCH(UPDATE) : 在服务器更新资源(客户端提供改变的属性).
• DELETE(DELETE) : 在服务器删除资源.

WebApi 在 Asp.NetCore 中的实现

这里以用户增删改查为例.

创建WebApi项目.

参考ASP.NET Core WebAPI 开发-新建WebAPI项目.

注意,本文建立的Asp.NetCore WebApi项目选择.net core版本是2.2,不建议使用其他版本,2.1版本下会遇到依赖文件冲突问题!所以一定要选择2.2版本的.net core.

集成Entity Framework Core操作Mysql

安装相关的包(为Xxxx.Infrastructure项目安装)

• Microsoft.EntityFrameworkCore.Design
• Pomelo.EntityFrameworkCore.MySql

这里注意一下,Mysql官方的包是 MySql.Data.EntityFrameworkCore,但是这个包有bug,我在github上看到有人说有替代方案 - Pomelo.EntityFrameworkCore.MySql,经过尝试,后者比前者好用.所有这里就选择后者了.使用前者的话可能会导致数据库迁移失败(Update的时候).

PS: Mysql文档原文:

Install the MySql.Data.EntityFrameworkCore NuGet package.
For EF Core 1.1 only: If you plan to scaffold a database, install the MySql.Data.EntityFrameworkCore.Design NuGet package as well.

EFCore - MySql文档
Mysql版本要求:
Mysql版本要高于5.7
使用最新版本的Mysql Connector(2019 6/27 目前是8.x).

为Xxxx.Infrastructure项目安装EFCore相关的包:

为Xxxx.Api项目安装 Pomelo.EntityFrameworkCore.MySql

建立Entity和Context

ApiUser

namespace ApiStudy.Core.Entities
{
    using System;

    public class ApiUser
    {
        public Guid Guid { get; set; }
        public string Name { get; set; }
        public string Passwd { get; set; }
        public DateTime RegistrationDate { get; set; }
        public DateTime Birth { get; set; }
        public string ProfilePhotoUrl { get; set; }
        public string PhoneNumber { get; set; }
        public string Email { get; set; }
    }
}

UserContext

namespace ApiStudy.Infrastructure.Database
{
    using ApiStudy.Core.Entities;
    using Microsoft.EntityFrameworkCore;

    public class UserContext:DbContext
    {
        public UserContext(DbContextOptions<UserContext> options): base(options)
        {
        }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Entity<ApiUser>().HasKey(u => u.Guid);

            base.OnModelCreating(modelBuilder);
        }

        public DbSet<ApiUser> ApiUsers { get; set; }
    }
}

ConfigureService中注入EF服务

services.AddDbContext<UserContext>(options =>
            {
                string connString = "Server=Xxx:xxx:xxx:xxx;Database=Xxxx;Uid=root;Pwd=Xxxxx; ";
                options.UseMySQL(connString);
            });

迁移数据库

• 在Tools > NuGet Package Manager > Package Manager Console输入命令.
• Add-Migration Xxx 添加迁移.
  PS : 如果迁移不想要,使用 Remove-Migration 命令删除迁移.
• Update-Database 更新到数据库.

迁移数据库失败, 提示 Unable to create an object of type 'Context'. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728

原因应该是EfCore迁移工具不知道如何创建 DbContext 导致的.

解决方案

在DbContext所在的项目下新建一个类:

/// 

/// 设计时DbContext的创建, 告诉EF Core迁移工具如何创建DbContext
/// 
public class <Xxxx>ContextFactory : IDesignTimeDbContextFactory<<Xxxx>Context>
{
    public <Xxxx>Context CreateDbContext(string[] args)
    {
        var optionsBuilder = new DbContextOptionsBuilder<<Xxxx>Context>();
        optionsBuilder.UseMySql(
            @"Server=[服务器ip];Database=[数据库]];Uid=[用户名];Pwd=[密码];");

        return new <Xxxx>Context(optionsBuilder.Options);
    }
}

数据库迁移结果

3.2.6. 为数据库创建种子数据

• 写一个创建种子数据的类

  UserContextSeed

  namespace ApiStudy.Infrastructure.Database
  {
      using ApiStudy.Core.Entities;
      using Microsoft.Extensions.Logging;
      using System;
      using System.Linq;
      using System.Threading.Tasks;
  
      public class UserContextSeed
      {
          public static async Task SeedAsync(UserContext context,ILoggerFactory loggerFactory)
          {
              try
              {
                  if (!context.ApiUsers.Any())
                  {
                      context.ApiUsers.AddRange(
                          new ApiUser
                          {
                              Guid = Guid.NewGuid(),
                              Name = "la",
                              Birth = new DateTime(1998, 11, 29),
                              RegistrationDate = new DateTime(2019, 6, 28),
                              Passwd = "123587",
                              ProfilePhotoUrl = "https://www.laggage.top/",
                              PhoneNumber = "10086",
                              Email = "[email protected]"
                          },
                          new ApiUser
                          {
                              Guid = Guid.NewGuid(),
                              Name = "David",
                              Birth = new DateTime(1995, 8, 29),
                              RegistrationDate = new DateTime(2019, 3, 28),
                              Passwd = "awt87495987",
                              ProfilePhotoUrl = "https://www.laggage.top/",
                              PhoneNumber = "1008611",
                              Email = "[email protected]"
                          },
                          new ApiUser
                          {
                              Guid = Guid.NewGuid(),
                              Name = "David",
                              Birth = new DateTime(2001, 8, 19),
                              RegistrationDate = new DateTime(2019, 4, 25),
                              Passwd = "awt87495987",
                              ProfilePhotoUrl = "https://www.laggage.top/",
                              PhoneNumber = "1008611",
                              Email = "[email protected]"
                          },
                          new ApiUser
                          {
                              Guid = Guid.NewGuid(),
                              Name = "Linus",
                              Birth = new DateTime(1999, 10, 26),
                              RegistrationDate = new DateTime(2018, 2, 8),
                              Passwd = "awt87495987",
                              ProfilePhotoUrl = "https://www.laggage.top/",
                              PhoneNumber = "17084759987",
                              Email = "[email protected]"
                          },
                          new ApiUser
                          {
                              Guid = Guid.NewGuid(),
                              Name = "YouYou",
                              Birth = new DateTime(1992, 1, 26),
                              RegistrationDate = new DateTime(2015, 7, 8),
                              Passwd = "grwe874864987",
                              ProfilePhotoUrl = "https://www.laggage.top/",
                              PhoneNumber = "17084759987",
                              Email = "[email protected]"
                          },
                          new ApiUser
                          {
                              Guid = Guid.NewGuid(),
                              Name = "小白",
                              Birth = new DateTime(1997, 9, 30),
                              RegistrationDate = new DateTime(2018, 11, 28),
                              Passwd = "gewa749864",
                              ProfilePhotoUrl = "https://www.laggage.top/",
                              PhoneNumber = "17084759987",
                              Email = "[email protected]"
                          });
  
                      await context.SaveChangesAsync();
                  }
              }
              catch(Exception ex)
              {
                  ILogger logger = loggerFactory.CreateLogger<UserContextSeed>();
                  logger.LogError(ex, "Error occurred while seeding database");
              }
          }
      }
  }
  
  

• 修改Program.Main方法

  Program.Main

  IWebHost host = CreateWebHostBuilder(args).Build();
  
  using (IServiceScope scope = host.Services.CreateScope())
  {
      IServiceProvider provider = scope.ServiceProvider;
      UserContext userContext = provider.GetService<UserContext>();
      ILoggerFactory loggerFactory = provider.GetService<ILoggerFactory>();
      UserContextSeed.SeedAsync(userContext, loggerFactory).Wait();
  }
  
  host.Run();
  

这个时候运行程序会出现异常,打断点看一下异常信息:Data too long for column 'Guid' at row 1

可以猜到,Mysql的varbinary(16)放不下C# Guid.NewGuid()方法生成的Guid,所以配置一下数据库Guid字段类型为varchar(256)可以解决问题.

解决方案:
修改 UserContext.OnModelCreating 方法
配置一下 ApiUser.Guid 属性到Mysql数据库的映射:

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    modelBuilder.Entity().Property(p => p.Guid)
        .HasColumnType("nvarchar(256)");
    modelBuilder.Entity().HasKey(u => u.Guid);
    
    base.OnModelCreating(modelBuilder);
}

支持https

将所有http请求全部映射到https

Startup中:
ConfigureServices方法注册,并配置端口和状态码等:
services.AddHttpsRedirection(…)

services.AddHttpsRedirection(options =>
                {
                    options.RedirectStatusCode = StatusCodes.Status307TemporaryRedirect;
                    options.HttpsPort = 5001;
                });

Configure方法使用该中间件:

app.UseHttpsRedirection()

支持HSTS

ConfigureServices方法注册
看官方文档

services.AddHsts(options =>
{
    options.Preload = true;
    options.IncludeSubDomains = true;
    options.MaxAge = TimeSpan.FromDays(60);
    options.ExcludedHosts.Add("example.com");
    options.ExcludedHosts.Add("www.example.com");
});

Configure方法配置中间件管道

app.UseHsts();

注意 app.UseHsts() 方法最好放在 app.UseHttps() 方法之后.

使用SerilLog

有关日志的微软官方文档

SerilLog github仓库
该github仓库上有详细的使用说明.

使用方法:

安装nuget包

• Serilog.AspNetCore
• Serilog.Sinks.Console

添加代码

Program.Main方法中:

Log.Logger = new LoggerConfiguration()
            .MinimumLevel.Debug()
            .MinimumLevel.Override("Microsoft", LogEventLevel.Information)
            .Enrich.FromLogContext()
            .WriteTo.Console()
            .CreateLogger();

修改Program.CreateWebHostBuilder(...)

 public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .UseStartup<Startup>()
                .UseSerilog(); // <-- Add this line;
 }

自行测试

Asp.NetCore配置文件

默认配置文件

默认 appsettings.json
ConfigurationBuilder().AddJsonFile("appsettings.json").Build()-->IConfigurationRoot(IConfiguration)

获得配置

IConfiguration[“Key:ChildKey”]
针对”ConnectionStrings:xxx”,可以使用IConfiguration.GetConnectionString(“xxx”)

private static IConfiguration Configuration { get; set; }

public StartupDevelopment(IConfiguration config)
{
    Configuration = config;
}

...

Configuration[“Key:ChildKey”]

自定义一个异常处理,ExceptionHandler

弄一个类,写一个扩展方法处理异常

namespace ApiStudy.Api.Extensions
{
    using Microsoft.AspNetCore.Builder;
    using Microsoft.AspNetCore.Http;
    using Microsoft.Extensions.Logging;
    using System;

    public static class ExceptionHandlingExtensions
    {
        public static void UseCustomExceptionHandler(this IApplicationBuilder app,ILoggerFactory loggerFactory)
        {
            app.UseExceptionHandler(
                builder => builder.Run(async context =>
                {
                    context.Response.StatusCode = StatusCodes.Status500InternalServerError;
                    context.Response.ContentType = "application/json";

                    Exception ex = context.Features.Get<Exception>();
                    if (!(ex is null))
                    {
                        ILogger logger = loggerFactory.CreateLogger("ApiStudy.Api.Extensions.ExceptionHandlingExtensions");
                        logger.LogError(ex, "Error occurred.");
                    }
                    await context.Response.WriteAsync(ex?.Message ?? "Error occurred, but cannot get exception message.For more detail, go to see the log.");
                }));
        }
    }
}

在Configuration中使用扩展方法

// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, ILoggerFactory loggerFactory)
{
    app.UseCustomExceptionHandler(loggerFactory);  //modified code

    //app.UseDeveloperExceptionPage();
    app.UseHsts();
    app.UseHttpsRedirection();

    app.UseMvc(); //使用默认路由
}

实现数据接口类(Resource),使用AutoMapper在Resource和Entity中映射

9.1. 为Entity类创建对应的Resource类

ApiUserResource

namespace ApiStudy.Infrastructure.Resources
{
    using System;

    public class ApiUserResource
    {
        public Guid Guid { get; set; }
        public string Name { get; set; }
        //public string Passwd { get; set; }
        public DateTime RegistrationDate { get; set; }
        public DateTime Birth { get; set; }
        public string ProfilePhotoUrl { get; set; }
        public string PhoneNumber { get; set; }
        public string Email { get; set; }
    }
}

使用 AutoMapper

• 添加nuget包
  AutoMapper
AutoMapper.Extensions.Microsoft.DependencyInjection

• 配置映射
  可以创建Profile
  CreateMap()

  MappingProfile

  namespace ApiStudy.Api.Extensions
  {
      using ApiStudy.Core.Entities;
      using ApiStudy.Infrastructure.Resources;
      using AutoMapper;
      using System;
      using System.Text;
  
      public class MappingProfile : Profile
      {
          public MappingProfile()
          {
              CreateMap<ApiUser, ApiUserResource>()
                  .ForMember(
                  d => d.Passwd, 
                  opt => opt.AddTransform(s => Convert.ToBase64String(Encoding.Default.GetBytes(s))));
  
              CreateMap<ApiUserResource, ApiUser>()
                  .ForMember(
                  d => d.Passwd,
                  opt => opt.AddTransform(s => Encoding.Default.GetString(Convert.FromBase64String(s))));
          }
      }
  }
  
  

• 注入服务 -> services.AddAutoMapper()

使用FluentValidation

FluentValidation官网

安装Nuget包

• FluentValidation
• FluentValidation.AspNetCore

为每一个Resource配置验证器

• 继承于AbstractValidator

  ApiUserResourceValidator

  namespace ApiStudy.Infrastructure.Resources
  {
      using FluentValidation;
  
      public class ApiUserResourceValidator : AbstractValidator<ApiUserResource>
      {
          public ApiUserResourceValidator()
          {
              RuleFor(s => s.Name)
                  .MaximumLength(80)
                  .WithName("用户名")
                  .WithMessage("{PropertyName}的最大长度为80")
                  .NotEmpty()
                  .WithMessage("{PropertyName}不能为空!");
          }
      }
  }
  

• 注册到容器:services.AddTransient<>()
  services.AddTransient, ApiUserResourceValidator>();

实现Http Get(翻页,过滤,排序)

基本的Get实现

[HttpGet]
public async Task<IActionResult> Get()
{
    IEnumerable<ApiUser> apiUsers = await _apiUserRepository.GetAllApiUsersAsync();

    IEnumerable<ApiUserResource> apiUserResources = 
        _mapper.Map<IEnumerable<ApiUser>,IEnumerable<ApiUserResource>>(apiUsers);

    return Ok(apiUserResources);
}

[HttpGet("{guid}")]
public async Task<IActionResult> Get(string guid)
{
    ApiUser apiUser = await _apiUserRepository.GetApiUserByGuidAsync(Guid.Parse(guid));

    if (apiUser is null) return NotFound();

    ApiUserResource apiUserResource = _mapper.Map<ApiUser,ApiUserResource>(apiUser);

    return Ok(apiUserResource);
}

资源命名

资源应该使用名词,例

• api/getusers就是不正确的.
• GET　api/users就是正确的

资源命名层次结构

• 例如api/department/{departmentId}/emoloyees, 这就表示了 department (部门)和员工
  (employee)之前是主从关系.
• 而api/department/{departmentId}/emoloyees/{employeeId},就表示了该部门下的某个员
  工.

内容协商

ASP.NET Core支持输出和输入两种格式化器.

• 用于输出的media type放在Accept Header里,表示客户端接受这种格式的输出.
• 用于输入的media type放Content-Type Header里,表示客户端传进来的数据是这种格式.
• ReturnHttpNotAcceptable设为true,如果客户端请求不支持的数据格式,就会返回406.

  services.AddMvc(options =>
  {
      options.ReturnHttpNotAcceptable = true;
  });
  

• 支持输出XML格式:options.OutputFormatters.Add(newXmlDataContractSerializerOutputFormatter());

翻页

构造翻页请求参数类

QueryParameters

namespace ApiStudy.Core.Entities
{
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Runtime.CompilerServices;

    public abstract class QueryParameters : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        private const int DefaultPageSize = 10;
        private const int DefaultMaxPageSize = 100;

        private int _pageIndex = 1;
        public virtual int PageIndex
        {
            get => _pageIndex;
            set => SetField(ref _pageIndex, value);
        }

        private int _pageSize = DefaultPageSize;
        public virtual int PageSize
        {
            get => _pageSize;
            set => SetField(ref _pageSize, value);
        }

        private int _maxPageSize = DefaultMaxPageSize;
        public virtual int MaxPageSize
        {
            get => _maxPageSize;
            set => SetField(ref _maxPageSize, value);
        }

        public string OrderBy { get; set; }
        public string Fields { get; set; }

        protected void SetField<TField>(
            ref TField field,in TField newValue,[CallerMemberName] string propertyName = null)
        {
            if (EqualityComparer<TField>.Default.Equals(field, newValue))
                return;
            field = newValue;
            if (propertyName == nameof(PageSize) || propertyName == nameof(MaxPageSize)) SetPageSize();
            
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
            
        }

        private void SetPageSize()
        {
            if (_maxPageSize <= 0) _maxPageSize = DefaultMaxPageSize;
            if (_pageSize <= 0) _pageSize = DefaultPageSize;
            _pageSize = _pageSize > _maxPageSize ? _maxPageSize : _pageSize;
        }
    }
}

ApiUserParameters

namespace ApiStudy.Core.Entities
{
    public class ApiUserParameters:QueryParameters
    {
        public string UserName { get; set; }
    }
}

Repository实现支持翻页请求参数的方法

Repository相关代码

/*----- ApiUserRepository -----*/
public PaginatedList<ApiUser> GetAllApiUsers(ApiUserParameters parameters)
{
    return new PaginatedList<ApiUser>(
        parameters.PageIndex,
        parameters.PageSize,
        _context.ApiUsers.Count(),
        _context.ApiUsers.Skip(parameters.PageIndex * parameters.PageSize)
        .Take(parameters.PageSize));
}

public Task<PaginatedList<ApiUser>> GetAllApiUsersAsync(ApiUserParameters parameters)
{
    return Task.Run(() => GetAllApiUsers(parameters));
}

/*----- IApiUserRepository -----*/
PaginatedList<ApiUser> GetAllApiUsers(ApiUserParameters parameters);
Task<PaginatedList<ApiUser>> GetAllApiUsersAsync(ApiUserParameters parameters);

UserController部分代码

...

[HttpGet(Name = "GetAllApiUsers")]
public async Task<IActionResult> GetAllApiUsers(ApiUserParameters parameters)
{
    PaginatedList<ApiUser> apiUsers = await _apiUserRepository.GetAllApiUsersAsync(parameters);

    IEnumerable<ApiUserResource> apiUserResources = 
        _mapper.Map<IEnumerable<ApiUser>,IEnumerable<ApiUserResource>>(apiUsers);

    var meta = new
    {
        PageIndex = apiUsers.PageIndex,
        PageSize = apiUsers.PageSize,
        PageCount = apiUsers.PageCount,
        TotalItemsCount = apiUsers.TotalItemsCount,
        NextPageUrl = CreateApiUserUrl(parameters, ResourceUriType.NextPage),
        PreviousPageUrl = CreateApiUserUrl(parameters, ResourceUriType.PreviousPage)
    };
    Response.Headers.Add(
        "X-Pagination",
        JsonConvert.SerializeObject(
            meta, 
            new JsonSerializerSettings
            { ContractResolver = new CamelCasePropertyNamesContractResolver() }));
    return Ok(apiUserResources);
}

...

private string CreateApiUserUrl(ApiUserParameters parameters,ResourceUriType uriType)
{
    var param = new ApiUserParameters
    {
        PageIndex = parameters.PageIndex,
        PageSize = parameters.PageSize
    };
    switch (uriType)
    {
        case ResourceUriType.PreviousPage:
            param.PageIndex--;
            break;
        case ResourceUriType.NextPage:
            param.PageIndex++;
            break;
        case ResourceUriType.CurrentPage:
            break;
        default:break;
    }
    return Url.Link("GetAllApiUsers", parameters);
}

PS注意,为HttpGet方法添加参数的话,在.net core2.2版本下,去掉那个ApiUserController上的 [ApiController());] 特性,否则参数传不进来..net core3.0中据说已经修复这个问题.

搜索(过滤)

修改Repository代码:

 public PaginatedList<ApiUser> GetAllApiUsers(ApiUserParameters parameters)
{
    IQueryable<ApiUser> query = _context.ApiUsers.AsQueryable();
    query = query.Skip(parameters.PageIndex * parameters.PageSize)
            .Take(parameters.PageSize);

    if (!string.IsNullOrEmpty(parameters.UserName))
        query = _context.ApiUsers.Where(
            x => StringComparer.OrdinalIgnoreCase.Compare(x.Name, parameters.UserName) == 0);

    return new PaginatedList<ApiUser>(
        parameters.PageIndex,
        parameters.PageSize,
        query.Count(),
        query);
}

排序

>排序思路

• 需要安装System.Linq.Dynamic.Core

思路:

• PropertyMappingContainer
  • PropertyMapping(ApiUserPropertyMapping)
    • MappedProperty

MappedProperty

namespace ApiStudy.Infrastructure.Services
{
    public struct MappedProperty
    {
        public MappedProperty(string name, bool revert = false)
        {
            Name = name;
            Revert = revert;
        }

        public string Name { get; set; }
        public bool Revert { get; set; }
    }
}

IPropertyMapping

namespace ApiStudy.Infrastructure.Services
{
    using System.Collections.Generic;

    public interface IPropertyMapping
    {
        Dictionary<string, List<MappedProperty>> MappingDictionary { get; }
    }
}

PropertyMapping

namespace ApiStudy.Infrastructure.Services
{
    using System.Collections.Generic;

    public abstract class PropertyMapping<TSource,TDestination> : IPropertyMapping
    {
        public Dictionary<string, List<MappedProperty>> MappingDictionary { get; }

        public PropertyMapping(Dictionary<string, List<MappedProperty>> MappingDict)
        {
            MappingDictionary = MappingDict;
        }
    }
}

IPropertyMappingContainer

namespace ApiStudy.Infrastructure.Services
{
    public interface IPropertyMappingContainer
    {
        void Register<T>() where T : IPropertyMapping, new();
        IPropertyMapping Resolve<TSource, TDestination>();
        bool ValidateMappingExistsFor<TSource, TDestination>(string fields);
    }
}

PropertyMappingContainer

namespace ApiStudy.Infrastructure.Services
{
    using System;
    using System.Linq;
    using System.Collections.Generic;

    public class PropertyMappingContainer : IPropertyMappingContainer
    {
        protected internal readonly IList<IPropertyMapping> PropertyMappings = new List<IPropertyMapping>();

        public void Register<T>() where T : IPropertyMapping, new()
        {
            if (PropertyMappings.Any(x => x.GetType() == typeof(T))) return;
            PropertyMappings.Add(new T());
        }

        public IPropertyMapping Resolve<TSource,TDestination>()
        {
            IEnumerable<PropertyMapping<TSource, TDestination>> result = PropertyMappings.OfType<PropertyMapping<TSource,TDestination>>();
            if (result.Count() > 0)
                return result.First();
            throw new InvalidCastException(
               string.Format( "Cannot find property mapping instance for {0}, {1}", typeof(TSource), typeof(TDestination)));
        }

        public bool ValidateMappingExistsFor<TSource, TDestination>(string fields)
        {
            if (string.IsNullOrEmpty(fields)) return true;

            IPropertyMapping propertyMapping = Resolve<TSource, TDestination>();

            string[] splitFields = fields.Split(',');

            foreach(string property in splitFields)
            {
                string trimmedProperty = property.Trim();
                int indexOfFirstWhiteSpace = trimmedProperty.IndexOf(' ');
                string propertyName = indexOfFirstWhiteSpace <= 0 ? trimmedProperty : trimmedProperty.Remove(indexOfFirstWhiteSpace);
                
                if (!propertyMapping.MappingDictionary.Keys.Any(x => string.Equals(propertyName,x,StringComparison.OrdinalIgnoreCase))) return false;
            }
            return true;
        }
    }
}

QueryExtensions

namespace ApiStudy.Infrastructure.Extensions
{
    using ApiStudy.Infrastructure.Services;
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Linq.Dynamic.Core;

    public static class QueryExtensions
    {
        public static IQueryable<T> ApplySort<T>(
           this IQueryable<T> data,in string orderBy,in IPropertyMapping propertyMapping)
        {
            if (data == null) throw new ArgumentNullException(nameof(data));
            if (string.IsNullOrEmpty(orderBy)) return data;

            string[] splitOrderBy = orderBy.Split(',');
            foreach(string property in splitOrderBy)
            {
                string trimmedProperty = property.Trim();
                int indexOfFirstSpace = trimmedProperty.IndexOf(' ');
                bool desc = trimmedProperty.EndsWith(" desc");
                string propertyName = indexOfFirstSpace > 0 ? trimmedProperty.Remove(indexOfFirstSpace) : trimmedProperty;
                propertyName = propertyMapping.MappingDictionary.Keys.FirstOrDefault(
                    x => string.Equals(x, propertyName, StringComparison.OrdinalIgnoreCase)); //ignore case of sort property

                if (!propertyMapping.MappingDictionary.TryGetValue(
                    propertyName, out List<MappedProperty> mappedProperties))
                    throw new InvalidCastException($"key mapping for {propertyName} is missing");

                mappedProperties.Reverse();
                foreach(MappedProperty mappedProperty in mappedProperties)
                {
                    if (mappedProperty.Revert) desc = !desc;
                    data = data.OrderBy($"{mappedProperty.Name} {(desc ? "descending" : "ascending")} ");
                }
            }
            return data;
        }
    }
}

UserController 部分代码

[HttpGet(Name = "GetAllApiUsers")]
public async Task<IActionResult> GetAllApiUsers(ApiUserParameters parameters)
{
    if (!_propertyMappingContainer.ValidateMappingExistsFor<ApiUserResource, ApiUser>(parameters.OrderBy))
        return BadRequest("can't find fields for sorting.");

    PaginatedList<ApiUser> apiUsers = await _apiUserRepository.GetAllApiUsersAsync(parameters);

    IEnumerable<ApiUserResource> apiUserResources =
        _mapper.Map<IEnumerable<ApiUser>, IEnumerable<ApiUserResource>>(apiUsers);

    IEnumerable<ApiUserResource> sortedApiUserResources =
        apiUserResources.AsQueryable().ApplySort(
            parameters.OrderBy, _propertyMappingContainer.Resolve<ApiUserResource, ApiUser>());

    var meta = new
    {
        apiUsers.PageIndex,
        apiUsers.PageSize,
        apiUsers.PageCount,
        apiUsers.TotalItemsCount,
        PreviousPageUrl = apiUsers.HasPreviousPage ? CreateApiUserUrl(parameters, ResourceUriType.PreviousPage) : string.Empty,
        NextPageUrl = apiUsers.HasNextPage ? CreateApiUserUrl(parameters, ResourceUriType.NextPage) : string.Empty,
    };
    Response.Headers.Add(
        "X-Pagination",
        JsonConvert.SerializeObject(
            meta,
            new JsonSerializerSettings
            { ContractResolver = new CamelCasePropertyNamesContractResolver() }));
    return Ok(sortedApiUserResources);
}

private string CreateApiUserUrl(ApiUserParameters parameters, ResourceUriType uriType)
{
    var param = new {
        parameters.PageIndex,
        parameters.PageSize
    };
    switch (uriType)
    {
        case ResourceUriType.PreviousPage:
            param = new
            {
                PageIndex = parameters.PageIndex - 1,
                parameters.PageSize
            };
            break;
        case ResourceUriType.NextPage:
            param = new
            {
                PageIndex = parameters.PageIndex + 1,
                parameters.PageSize
            };
            break;
        case ResourceUriType.CurrentPage:
            break;
        default: break;
    }
    return Url.Link("GetAllApiUsers", param);
}

资源塑形(Resource shaping)

返回 资源的指定字段

ApiStudy.Infrastructure.Extensions.TypeExtensions

namespace ApiStudy.Infrastructure.Extensions
{
    using System;
    using System.Collections.Generic;
    using System.Reflection;

    public static class TypeExtensions
    {
        public static IEnumerable<PropertyInfo> GetProeprties(this Type source, string fields = null)
        {
            List<PropertyInfo> propertyInfoList = new List<PropertyInfo>();
            if (string.IsNullOrEmpty(fields))
            {
                propertyInfoList.AddRange(source.GetProperties(BindingFlags.Public | BindingFlags.Instance));
            }
            else
            {
                string[] properties = fields.Trim().Split(',');
                foreach (string propertyName in properties)
                {
                    propertyInfoList.Add(
                        source.GetProperty(
                        propertyName.Trim(),
                        BindingFlags.Public | BindingFlags.Instance | BindingFlags.IgnoreCase));
                }
            }
            return propertyInfoList;
        }
    }
}

ApiStudy.Infrastructure.Extensions.ObjectExtensions

namespace ApiStudy.Infrastructure.Extensions
{
    using System.Collections.Generic;
    using System.Dynamic;
    using System.Linq;
    using System.Reflection;

    public static class ObjectExtensions
    {
        public static ExpandoObject ToDynamicObject(this object source, in string fields = null)
        {
            List<PropertyInfo> propertyInfoList = source.GetType().GetProeprties(fields).ToList();

            ExpandoObject expandoObject = new ExpandoObject();
            foreach (PropertyInfo propertyInfo in propertyInfoList)
            {
                try
                {
                    (expandoObject as IDictionary<string, object>).Add(
                    propertyInfo.Name, propertyInfo.GetValue(source));
                }
                catch { continue; }
            }
            return expandoObject;
        }

        internal static ExpandoObject ToDynamicObject(this object source, in IEnumerable<PropertyInfo> propertyInfos, in string fields = null)
        {
            ExpandoObject expandoObject = new ExpandoObject();
            foreach (PropertyInfo propertyInfo in propertyInfos)
            {
                try
                {
                    (expandoObject as IDictionary<string, object>).Add(
                    propertyInfo.Name, propertyInfo.GetValue(source));
                }
                catch { continue; }
            }
            return expandoObject;
        }
    }
}

ApiStudy.Infrastructure.Extensions.IEnumerableExtensions

namespace ApiStudy.Infrastructure.Extensions
{
    using System;
    using System.Collections.Generic;
    using System.Dynamic;
    using System.Linq;
    using System.Reflection;

    public static class IEnumerableExtensions
    {
        public static IEnumerable<ExpandoObject> ToDynamicObject<T>(
            this IEnumerable<T> source,in string fields = null)
        {
            if (source == null) throw new ArgumentNullException(nameof(source));

            List<ExpandoObject> expandoObejctList = new List<ExpandoObject>();
            List<PropertyInfo> propertyInfoList = typeof(T).GetProeprties(fields).ToList();
            foreach(T x in source)
            {
                expandoObejctList.Add(x.ToDynamicObject(propertyInfoList, fields));
            }
            return expandoObejctList;
        }
    }
}

ApiStudy.Infrastructure.Services.TypeHelperServices

namespace ApiStudy.Infrastructure.Services
{
    using System.Reflection;

    public class TypeHelperServices : ITypeHelperServices
    {
        public bool HasProperties<T>(string fields)
        {
            if (string.IsNullOrEmpty(fields)) return true;

            string[] splitFields = fields.Split(',');
            foreach(string splitField in splitFields)
            {
                string proeprtyName = splitField.Trim();
                PropertyInfo propertyInfo = typeof(T).GetProperty(
                    proeprtyName, BindingFlags.Public | BindingFlags.Instance | BindingFlags.IgnoreCase);
                if (propertyInfo == null) return false;
            }
            return true;
        }
    }
}

UserContext.GetAllApiUsers(), UserContext.Get()

[HttpGet(Name = "GetAllApiUsers")]
public async Task<IActionResult> GetAllApiUsers(ApiUserParameters parameters)
{
    //added code
    if (!_typeHelper.HasProperties<ApiUserResource>(parameters.Fields))
        return BadRequest("fields not exist.");

    if (!_propertyMappingContainer.ValidateMappingExistsFor<ApiUserResource, ApiUser>(parameters.OrderBy))
        return BadRequest("can't find fields for sorting.");

    PaginatedList<ApiUser> apiUsers = await _apiUserRepository.GetAllApiUsersAsync(parameters);

    IEnumerable<ApiUserResource> apiUserResources =
        _mapper.Map<IEnumerable<ApiUser>, IEnumerable<ApiUserResource>>(apiUsers);

    IEnumerable<ApiUserResource> sortedApiUserResources =
        apiUserResources.AsQueryable().ApplySort(
            parameters.OrderBy, _propertyMappingContainer.Resolve<ApiUserResource, ApiUser>());

    //modified code
    IEnumerable<ExpandoObject> sharpedApiUserResources =
        sortedApiUserResources.ToDynamicObject(parameters.Fields);

    var meta = new
    {
        apiUsers.PageIndex,
        apiUsers.PageSize,
        apiUsers.PageCount,
        apiUsers.TotalItemsCount,
        PreviousPageUrl = apiUsers.HasPreviousPage ? CreateApiUserUrl(parameters, ResourceUriType.PreviousPage) : string.Empty,
        NextPageUrl = apiUsers.HasNextPage ? CreateApiUserUrl(parameters, ResourceUriType.NextPage) : string.Empty,
    };
    Response.Headers.Add(
        "X-Pagination",
        JsonConvert.SerializeObject(
            meta,
            new JsonSerializerSettings
            { ContractResolver = new CamelCasePropertyNamesContractResolver() }));
    //modified code
    return Ok(sharpedApiUserResources);
}

配置返回的json名称风格为CamelCase

StartupDevelopment.ConfigureServices

services.AddMvc(options =>
    {
        options.ReturnHttpNotAcceptable = true;
        options.OutputFormatters.Add(new XmlDataContractSerializerOutputFormatter());
    })
        .AddJsonOptions(options =>
        {
            //added code
            options.SerializerSettings.ContractResolver = new CamelCasePropertyNamesContractResolver();
        });

HATEOAS

REST里最复杂的约束,构建成熟RESTAPI的核心

• 可进化性,自我描述
• 超媒体(Hypermedia,例如超链接)驱动如何消
  费和使用API

UserContext

private IEnumerable<LinkResource> CreateLinksForApiUser(string guid,string fields = null)
{
    List<LinkResource> linkResources = new List<LinkResource>();
    if (string.IsNullOrEmpty(fields))
    {
        linkResources.Add(
            new LinkResource(Url.Link("GetApiUser", new { guid }), "self", "get"));
    }
    else
    {
        linkResources.Add(
            new LinkResource(Url.Link("GetApiUser", new { guid, fields }), "self", "get"));
    }

    linkResources.Add(
            new LinkResource(Url.Link("DeleteApiUser", new { guid }), "self", "Get"));
    return linkResources;
}

private IEnumerable<LinkResource> CreateLinksForApiUsers(ApiUserParameters parameters,bool hasPrevious,bool hasNext)
{
    List<LinkResource> resources = new List<LinkResource>();

    resources.Add(
            new LinkResource(
                CreateApiUserUrl(parameters,ResourceUriType.CurrentPage),
                "current_page", "get"));
    if (hasPrevious)
        resources.Add(
            new LinkResource(
                CreateApiUserUrl(parameters, ResourceUriType.PreviousPage),
                "previous_page", "get"));
    if (hasNext)
        resources.Add(
            new LinkResource(
                CreateApiUserUrl(parameters, ResourceUriType.NextPage),
                "next_page", "get"));

    return resources;
}

[HttpGet(Name = "GetAllApiUsers")]
public async Task<IActionResult> GetAllApiUsers(ApiUserParameters parameters)
{
    if (!_typeHelper.HasProperties<ApiUserResource>(parameters.Fields))
        return BadRequest("fields not exist.");

    if (!_propertyMappingContainer.ValidateMappingExistsFor<ApiUserResource, ApiUser>(parameters.OrderBy))
        return BadRequest("can't find fields for sorting.");

    PaginatedList<ApiUser> apiUsers = await _apiUserRepository.GetAllApiUsersAsync(parameters);

    IEnumerable<ApiUserResource> apiUserResources =
        _mapper.Map<IEnumerable<ApiUser>, IEnumerable<ApiUserResource>>(apiUsers);

    IEnumerable<ApiUserResource> sortedApiUserResources =
        apiUserResources.AsQueryable().ApplySort(
            parameters.OrderBy, _propertyMappingContainer.Resolve<ApiUserResource, ApiUser>());

    IEnumerable<ExpandoObject> shapedApiUserResources =
        sortedApiUserResources.ToDynamicObject(parameters.Fields);

    IEnumerable<ExpandoObject> shapedApiUserResourcesWithLinks = shapedApiUserResources.Select(
        x =>
        {
            IDictionary<string, object> dict = x as IDictionary<string, object>;
            if(dict.Keys.Contains("guid"))
                dict.Add("links", CreateLinksForApiUser(dict["guid"] as string));
            return dict as ExpandoObject;
        });

    var result = new
    {
        value = shapedApiUserResourcesWithLinks,
        links = CreateLinksForApiUsers(parameters, apiUsers.HasPreviousPage, apiUsers.HasNextPage)
    };

    var meta = new
    {
        apiUsers.PageIndex,
        apiUsers.PageSize,
        apiUsers.PageCount,
        apiUsers.TotalItemsCount,
        //PreviousPageUrl = apiUsers.HasPreviousPage ? CreateApiUserUrl(parameters, ResourceUriType.PreviousPage) : string.Empty,
        //NextPageUrl = apiUsers.HasNextPage ? CreateApiUserUrl(parameters, ResourceUriType.NextPage) : string.Empty,
    };
    Response.Headers.Add(
        "X-Pagination",
        JsonConvert.SerializeObject(
            meta,
            new JsonSerializerSettings
            { ContractResolver = new CamelCasePropertyNamesContractResolver() }));
    return Ok(result);
}

创建供应商特定媒体类型

• application/vnd.mycompany.hateoas+json
  • vnd是vendor的缩写，这一条是mime type的原则，表示这个媒体类型是供应商特定的
  • 自定义的标识，也可能还包括额外的值，这里我是用的是公司名，随后是hateoas表示返回的响应里面要
    包含链接
  • “+json”
• 在Startup里注册.

判断Media Type类型

• [FromHeader(Name = "Accept")] stringmediaType

//Startup.ConfigureServices 中注册媒体类型
services.AddMvc(options =>
    {
        options.ReturnHttpNotAcceptable = true;
        //options.OutputFormatters.Add(new XmlDataContractSerializerOutputFormatter());
        JsonOutputFormatter formatter = options.OutputFormatters.OfType<JsonOutputFormatter>().FirstOrDefault();
        formatter.SupportedMediaTypes.Add("application/vnd.laggage.hateoas+json");
    })

// get方法中判断媒体类型
if (mediaType == "application/json") 
    return Ok(shapedApiUserResources);
else if (mediaType == "application/vnd.laggage.hateoas+json")
{
    ...
    return;
}

注意,要是的 Action 认识 application/vnd.laggage.hateoss+json ,需要在Startup.ConfigureServices中注册这个媒体类型,上面的代码给出了具体操作.

UserContext

[HttpGet(Name = "GetAllApiUsers")]
public async Task<IActionResult> GetAllApiUsers(ApiUserParameters parameters,[FromHeader(Name = "Accept")] string mediaType)
{
    if (!_typeHelper.HasProperties<ApiUserResource>(parameters.Fields))
        return BadRequest("fields not exist.");

    if (!_propertyMappingContainer.ValidateMappingExistsFor<ApiUserResource, ApiUser>(parameters.OrderBy))
        return BadRequest("can't find fields for sorting.");

    PaginatedList<ApiUser> apiUsers = await _apiUserRepository.GetAllApiUsersAsync(parameters);

    IEnumerable<ApiUserResource> apiUserResources =
        _mapper.Map<IEnumerable<ApiUser>, IEnumerable<ApiUserResource>>(apiUsers);

    IEnumerable<ApiUserResource> sortedApiUserResources =
        apiUserResources.AsQueryable().ApplySort(
            parameters.OrderBy, _propertyMappingContainer.Resolve<ApiUserResource, ApiUser>());

    IEnumerable<ExpandoObject> shapedApiUserResources =
        sortedApiUserResources.ToDynamicObject(parameters.Fields);

    if (mediaType == "application/json") return Ok(shapedApiUserResources);
    else if (mediaType == "application/vnd.laggage.hateoas+json")
    {
        IEnumerable<ExpandoObject> shapedApiUserResourcesWithLinks = shapedApiUserResources.Select(
            x =>
            {
                IDictionary<string, object> dict = x as IDictionary<string, object>;
                if (dict.Keys.Contains("guid"))
                    dict.Add("links", CreateLinksForApiUser(
                                dict.FirstOrDefault(
                                    a => string.Equals(
                                        a.Key,"guid",StringComparison.OrdinalIgnoreCase))
                                .Value.ToString()));
                return dict as ExpandoObject;
            });

        var result = new
        {
            value = shapedApiUserResourcesWithLinks,
            links = CreateLinksForApiUsers(parameters, apiUsers.HasPreviousPage, apiUsers.HasNextPage)
        };

        var meta = new
        {
            apiUsers.PageIndex,
            apiUsers.PageSize,
            apiUsers.PageCount,
            apiUsers.TotalItemsCount,
        };
        Response.Headers.Add(
            "X-Pagination",
            JsonConvert.SerializeObject(
                meta,
                new JsonSerializerSettings
                { ContractResolver = new CamelCasePropertyNamesContractResolver() }));
        return Ok(result);
    }
    return NotFound($"Can't find resources for the given media type: [{mediaType}].");
}

[HttpGet("{guid}",Name = "GetApiUser")]
public async Task<IActionResult> Get(string guid, [FromHeader(Name = "Accept")] string mediaType , string fields = null)
{
    if (!_typeHelper.HasProperties<ApiUserResource>(fields))
        return BadRequest("fields not exist.");

    ApiUser apiUser = await _apiUserRepository.GetApiUserByGuidAsync(Guid.Parse(guid));

    if (apiUser is null) return NotFound();
    ApiUserResource apiUserResource = _mapper.Map<ApiUser, ApiUserResource>(apiUser);

    ExpandoObject shapedApiUserResource = apiUserResource.ToDynamicObject(fields);
    if (mediaType == "application/json") return Ok(shapedApiUserResource);

    else if(mediaType == "application/vnd.laggage.hateoas+json")
    {

    
    IDictionary<string, object> shapedApiUserResourceWithLink = shapedApiUserResource as IDictionary<string, object>;
    shapedApiUserResourceWithLink.Add("links", CreateLinksForApiUser(guid, fields));

    return Ok(shapedApiUserResourceWithLink);
    }
    return NotFound(@"Can't find resource for the given media type: [{mediaType}].");
}

• 自定义Action约束.

RequestHeaderMatchingMediaTypeAttribute

[AttributeUsage(AttributeTargets.All, Inherited = true, AllowMultiple = true)]
public class RequestHeaderMatchingMediaTypeAttribute : Attribute, IActionConstraint
{
    private readonly string _requestHeaderToMatch;
    private readonly string[] _mediaTypes;

    public RequestHeaderMatchingMediaTypeAttribute(string requestHeaderToMatch, string[] mediaTypes)
    {
        _requestHeaderToMatch = requestHeaderToMatch;
        _mediaTypes = mediaTypes;
    }

    public bool Accept(ActionConstraintContext context)
    {
        var requestHeaders = context.RouteContext.HttpContext.Request.Headers;
        if (!requestHeaders.ContainsKey(_requestHeaderToMatch))
        {
            return false;
        }

        foreach (var mediaType in _mediaTypes)
        {
            var mediaTypeMatches = string.Equals(requestHeaders[_requestHeaderToMatch].ToString(),
                mediaType, StringComparison.OrdinalIgnoreCase);
            if (mediaTypeMatches)
            {
                return true;
            }
        }

        return false;
    }

    public int Order { get; } = 0;
}

UserContext

[HttpGet(Name = "GetAllApiUsers")]
[RequestHeaderMatchingMediaType("Accept",new string[] { "application/vnd.laggage.hateoas+json" })]
public async Task<IActionResult> GetHateoas(ApiUserParameters parameters)
{
    if (!_typeHelper.HasProperties<ApiUserResource>(parameters.Fields))
        return BadRequest("fields not exist.");

    if (!_propertyMappingContainer.ValidateMappingExistsFor<ApiUserResource, ApiUser>(parameters.OrderBy))
        return BadRequest("can't find fields for sorting.");

    PaginatedList<ApiUser> apiUsers = await _apiUserRepository.GetAllApiUsersAsync(parameters);

    IEnumerable<ApiUserResource> apiUserResources =
        _mapper.Map<IEnumerable<ApiUser>, IEnumerable<ApiUserResource>>(apiUsers);

    IEnumerable<ApiUserResource> sortedApiUserResources =
        apiUserResources.AsQueryable().ApplySort(
            parameters.OrderBy, _propertyMappingContainer.Resolve<ApiUserResource, ApiUser>());

    IEnumerable<ExpandoObject> shapedApiUserResources =
        sortedApiUserResources.ToDynamicObject(parameters.Fields);

    IEnumerable<ExpandoObject> shapedApiUserResourcesWithLinks = shapedApiUserResources.Select(
            x =>
            {
                IDictionary<string, object> dict = x as IDictionary<string, object>;
                if (dict.Keys.Contains("guid"))
                    dict.Add("links", CreateLinksForApiUser(
                                dict.FirstOrDefault(
                                    a => string.Equals(
                                        a.Key,"guid",StringComparison.OrdinalIgnoreCase))
                                .Value.ToString()));
                return dict as ExpandoObject;
            });

    var result = new
    {
        value = shapedApiUserResourcesWithLinks,
        links = CreateLinksForApiUsers(parameters, apiUsers.HasPreviousPage, apiUsers.HasNextPage)
    };

    var meta = new
    {
        apiUsers.PageIndex,
        apiUsers.PageSize,
        apiUsers.PageCount,
        apiUsers.TotalItemsCount,
    };
    Response.Headers.Add(
        "X-Pagination",
        JsonConvert.SerializeObject(
            meta,
            new JsonSerializerSettings
            { ContractResolver = new CamelCasePropertyNamesContractResolver() }));
    return Ok(result);
}

[HttpGet(Name = "GetAllApiUsers")]
[RequestHeaderMatchingMediaType("Accept",new string[] { "application/json" })]
public async Task<IActionResult> Get(ApiUserParameters parameters)
{
    if (!_typeHelper.HasProperties<ApiUserResource>(parameters.Fields))
        return BadRequest("fields not exist.");

    if (!_propertyMappingContainer.ValidateMappingExistsFor<ApiUserResource, ApiUser>(parameters.OrderBy))
        return BadRequest("can't find fields for sorting.");

    PaginatedList<ApiUser> apiUsers = await _apiUserRepository.GetAllApiUsersAsync(parameters);

    IEnumerable<ApiUserResource> apiUserResources =
        _mapper.Map<IEnumerable<ApiUser>, IEnumerable<ApiUserResource>>(apiUsers);

    IEnumerable<ApiUserResource> sortedApiUserResources =
        apiUserResources.AsQueryable().ApplySort(
            parameters.OrderBy, _propertyMappingContainer.Resolve<ApiUserResource, ApiUser>());

    IEnumerable<ExpandoObject> shapedApiUserResources =
        sortedApiUserResources.ToDynamicObject(parameters.Fields);

    return Ok(shapedApiUserResources);
}

[HttpGet("{guid}", Name = "GetApiUser")]
[RequestHeaderMatchingMediaType("Accept", new string[] { "application/vnd.laggage.hateoas+json" })]
public async Task<IActionResult> GetHateoas(string guid, string fields = null)
{
    if (!_typeHelper.HasProperties<ApiUserResource>(fields))
        return BadRequest("fields not exist.");

    ApiUser apiUser = await _apiUserRepository.GetApiUserByGuidAsync(Guid.Parse(guid));

    if (apiUser is null) return NotFound();
    ApiUserResource apiUserResource = _mapper.Map<ApiUser, ApiUserResource>(apiUser);

    ExpandoObject shapedApiUserResource = apiUserResource.ToDynamicObject(fields);

    IDictionary<string, object> shapedApiUserResourceWithLink = shapedApiUserResource as IDictionary<string, object>;
    shapedApiUserResourceWithLink.Add("links", CreateLinksForApiUser(guid, fields));

    return Ok(shapedApiUserResourceWithLink);
}

[HttpGet("{guid}", Name = "GetApiUser")]
[RequestHeaderMatchingMediaType("Accept", new string[] { "application/json" })]
public async Task<IActionResult> Get(string guid,  string fields = null)
{
    if (!_typeHelper.HasProperties<ApiUserResource>(fields))
        return BadRequest("fields not exist.");

    ApiUser apiUser = await _apiUserRepository.GetApiUserByGuidAsync(Guid.Parse(guid));

    if (apiUser is null) return NotFound();
    ApiUserResource apiUserResource = _mapper.Map<ApiUser, ApiUserResource>(apiUser);

    ExpandoObject shapedApiUserResource = apiUserResource.ToDynamicObject(fields);

    return Ok(shapedApiUserResource);
}

Post添加资源

Post - 不安全,非幂等
要返回添加好的资源,并且返回头中有获得新创建资源的连接.

安全性和幂等性

• 安全性是指方法执行后并不会改变资源的表述
• 幂等性是指方法无论执行多少次都会得到同样
  的结果
  

代码实现

StartUp中注册Fluent,用于验证

services.AddMvc(...)
        .AddFluentValidation();

services.AddTransient<IValidator<ApiUserAddResource>, ApiUserAddResourceValidator>();

ApiStudy.Infrastructure.Resources.ApiUserAddResourceValidator

namespace ApiStudy.Infrastructure.Resources
{
    using FluentValidation;

    public class ApiUserAddResourceValidator : AbstractValidator<ApiUserAddResource>
    {
        public ApiUserAddResourceValidator()
        {
            RuleFor(x => x.Name)
                .MaximumLength(20)                
                .WithName("用户名")
                .WithMessage("{PropertyName}的最大长度为20!")
                .NotNull()
                .WithMessage("{PropertyName}是必填的!")
                .NotEmpty()
                .WithMessage("{PropertyName}不能为空!");
            RuleFor(x => x.Passwd)
                .NotNull()
                .WithName("密码")
                .WithMessage("{PropertyName}是必填的!")
                .MinimumLength(6)
                .WithMessage("{PropertyName}的最小长度是6")
                .MaximumLength(16)
                .WithMessage("{PropertyName}的最大长度是16");
            RuleFor(x => x.PhoneNumber)
                .NotNull()
                .WithName("电话")
                .WithMessage("{PropertyName}是必填的!")
                .NotEmpty()
                .WithMessage("{PropertyName}不能为空!");
        }
    }
}

UserContext.AddApiUser()

[HttpPost(Name = "CreateApiUser")]
[RequestHeaderMatchingMediaType("Content-Type",new string[] { "application/vnd.laggage.create.apiuser+json" })]
[RequestHeaderMatchingMediaType("Accept",new string[] { "application/vnd.laggage.hateoas+json" })]
public async Task<IActionResult> AddUser([FromBody] ApiUserAddResource apiUser)
{
    if (!ModelState.IsValid)
        return UnprocessableEntity(ModelState);

    ApiUser newUser = _mapper.Map<ApiUser>(apiUser);
    newUser.Guid = Guid.NewGuid();
    newUser.ProfilePhotoUrl = $"www.eample.com/photo/{newUser.Guid}";
    newUser.RegistrationDate = DateTime.Now;

    await _apiUserRepository.AddApiUserAsync(newUser);
    if (!await _unitOfWork.SaveChangesAsync())
        throw new Exception("Failed to save changes");

    IDictionary<string, object> shapedUserResource = 
        _mapper.Map<ApiUserResource>(newUser)
        .ToDynamicObject() as IDictionary<string, object>;
    IEnumerable<LinkResource> links = CreateLinksForApiUser(newUser.Guid.ToString());
    shapedUserResource.Add("links", links);
    return CreatedAtRoute("GetApiUser",new { newUser.Guid }, shapedUserResource);
}

Delete

• 参数 : ID
• 幂等的
  • 多次请求的副作用和单次请求的副作用是一样的.每次发送了DELETE请求之后，服务器的状态都是一样的.
• 不安全

ApiStudy.Api.Controllers.UserController

[HttpDelete("{guid}",Name = "DeleteApiUser")]
public async Task<IActionResult> DeleteApiUser(string guid)
{
    ApiUser userToDelete = await _apiUserRepository.GetApiUserByGuidAsync(new Guid(guid));

    if (userToDelete == null) return NotFound();

    await _apiUserRepository.DeleteApiUserAsync(userToDelete);
    if (!await _unitOfWork.SaveChangesAsync())
        throw new Exception("Failed to delete apiUser");

    return NoContent();
}

PUT & PATCH

相关类:

ApiStudy.Infrastructure.Resources.ApiUserAddOrUpdateResource

namespace ApiStudy.Infrastructure.Resources
{
    using System;

    public abstract class ApiUserAddOrUpdateResource
    {
        public string Name { get; set; }
        public string Passwd { get; set; }
        public DateTime Birth { get; set; }
        public string PhoneNumber { get; set; }
        public string Email { get; set; }
    }
}

ApiStudy.Infrastructure.Resources.ApiUserAddResource

namespace ApiStudy.Infrastructure.Resources
{
    public class ApiUserAddResource:ApiUserAddOrUpdateResource
    {
    }
}

ApiStudy.Infrastructure.Resources.ApiUserUpdateResource

namespace ApiStudy.Infrastructure.Resources
{
    public class ApiUserUpdateResource : ApiUserAddOrUpdateResource
    {
    }
}

ApiStudy.Infrastructure.Resources.ApiUserAddOrUpdateResourceValidator

namespace ApiStudy.Infrastructure.Resources
{
    using FluentValidation;

    public class ApiUserAddOrUpdateResourceValidator<T> : AbstractValidator<T> where T: ApiUserAddOrUpdateResource
    {
        public ApiUserAddOrUpdateResourceValidator()
        {
            RuleFor(x => x.Name)
                .MaximumLength(20)                
                .WithName("用户名")
                .WithMessage("{PropertyName}的最大长度为20!")
                .NotNull()
                .WithMessage("{PropertyName}是必填的!")
                .NotEmpty()
                .WithMessage("{PropertyName}不能为空!");
            RuleFor(x => x.Passwd)
                .NotNull()
                .WithName("密码")
                .WithMessage("{PropertyName}是必填的!")
                .MinimumLength(6)
                .WithMessage("{PropertyName}的最小长度是6")
                .MaximumLength(16)
                .WithMessage("{PropertyName}的最大长度是16");
            RuleFor(x => x.PhoneNumber)
                .NotNull()
                .WithName("电话")
                .WithMessage("{PropertyName}是必填的!")
                .NotEmpty()
                .WithMessage("{PropertyName}不能为空!");
        }
    }
}

PUT 整体更新

• 返回204
• 参数
  • ID,
  • [FromBody]XxxxUpdateResource

ApiStudy.Api.Controllers.UpdateApiUser

[HttpPut("{guid}",Name = "PutApiUser")]
public async Task<IActionResult> UpdateApiUser(string guid,[FromBody] ApiUserUpdateResource apiUserUpdateResource)
{
    if (!ModelState.IsValid) return BadRequest(ModelState);

    ApiUser userToUpdate = await _apiUserRepository.GetApiUserByGuidAsync(new Guid(guid));
    if (userToUpdate == null) return NotFound();

    _mapper.Map(apiUserUpdateResource, userToUpdate);

    if (!await _unitOfWork.SaveChangesAsync())
        throw new Exception("Failed to update Entity of ApiUser");
    return NoContent();
}

PATCH

• Content-Type
  • application/json-patch+json
• 返回204
• 参数
  • ID
  • [FromBody] JsonPatchDocument
• op操作
  • 添加：{“op”: "add", "path": "/xxx", "value": "xxx"}，如果该属性不存，那么就添加该属性，如
    果属性存在，就改变属性的值。这个对静态类型不适用。
  • 删除：{“op”: "remove", "path": "/xxx"}，删除某个属性，或把它设为默认值（例如空值）。
  • 替换：{“op”: "replace", "path": "/xxx", "value": "xxx"}，改变属性的值，也可以理解为先执行
    了删除，然后进行添加。
  • 复制：{“op”: "copy", "from": "/xxx", "path": "/yyy"}，把某个属性的值赋给目标属性。
  • 移动：{“op”: "move", "from": "/xxx", "path": "/yyy"}，把源属性的值赋值给目标属性，并把源
    属性删除或设成默认值。
  • 测试：{“op”: "test", "path": "/xxx", "value": "xxx"}，测试目标属性的值和指定的值是一样的。
• path,资源的属性名
  • 可以有层级结构
• value 更新的值

[
    {
        "op":"replace",
        "path":"/name",
        "value":"阿黄"
    },
    {
        "op":"remove",
        "path":"/email"
    }
]

ApiStudy.Api.Controllers.UserContext.UpdateApiUser

[HttpPatch("{guid}",Name = "PatchApiUser")]
[RequestHeaderMatchingMediaType("Content-Type",new string[] { "application/vnd.laggage.patch.apiuser+json" })]
public async Task<IActionResult> UpdateApiUser(
    string guid,[FromBody] JsonPatchDocument<ApiUserUpdateResource> userUpdateDoc)
{
    if (userUpdateDoc == null) return BadRequest();

    ApiUser userToUpdate = await _apiUserRepository.GetApiUserByGuidAsync(new Guid(guid));
    if (userToUpdate is null) return NotFound();

    ApiUserUpdateResource userToUpdateResource = _mapper.Map<ApiUserUpdateResource>(userToUpdate);
    userUpdateDoc.ApplyTo(userToUpdateResource);

    _mapper.Map(userToUpdateResource, userToUpdate);
    if (!await _unitOfWork.SaveChangesAsync()) throw new Exception("Failed to update Entity of ApiUser");

    return NoContent();
}

Http常用方法总结

• GET(获取资源)：
  • GET api/countries，返回200，集合数据；找不到数据返回404。
  • GET api/countries/{id},返回200，单个数据；找不到返回404.
• DELETE(删除资源)
  • DELETE api/countries/{id}，成功204；没找到资源404。
  • DELETE api/countries，很少用，也是204或者404.
• POST (创建资源)：
  • POST api/countries,成功返回201和单个数据；如果资源没有创建则返回404
  • POST api/countries/{id}，肯定不会成功，返回404或409.
  • POST api/countrycollections，成功返回201和集合；没创建资源则返回404
• PUT (整体更新)：
  • PUT api/countries/{id},成功可以返回200，204；没找到资源则返回404
  • PUT api/countries，集合操作很少见，返回200，204或404
• PATCH(局部更新):
  • PATCHapi/countries/{id}，200单个数据，204或者404
  • PATCHapi/countries,集合操作很少见，返回200集合，204或404.