asp.net core模型绑定和模型验证

模型绑定以及模型验证

模型绑定

Demo：添加学生信息

1、在Controller中创建Create方法

				[HttpGet]
				public IActionResult Create()
        {
            return View();
        }
        
        [HttpPost]
        public IActionResult Create(Student student)
        {
           return RedirectToAction("Details", new {id = newStudent.Id}); 
        }

2、创建对应的View视图

@model Student
@{
    ViewBag.Title = "创建学生信息";
}
<form asp-controller="home"
      asp-action="create"
      method="post"
      class="mt-3">
    <div class="form-group row">
        <div class="col-sm-10">
            <input asp-for="Name" class="form-control" placeholder="请输入名字"/>
        </div>
    </div>
    <div class="form-group row">
        <div class="col-sm-10">
            <span asp-validation-for="Email" class="text-danger"></span>
        </div>
    </div>
    <div class="form-group row">
        <label asp-for="ClassName" class="col-sm-2 col-form-label"></label>
        <div class="col-sm-10">
            <select asp-for="ClassName"
                    asp-items="Html.GetEnumSelectList()"
                    class="custom-select mr-sm-2">
            </select>
        </div>
    </div>
    <div class="col-sm-10">
        <button type="submit" class="btn-primary">创建</button>
    </div>
</form>

要将HTTP的请求数据绑定到控制器操作方法上对应的参数上，模型绑定将按以下顺序在以下位置查找来自HTTP请求的数据。

Form values：表单中值

Route values：路由中的值

Query strings：查询字符串

模型验证

Demo：添加学生信息验证

第一步，在对应的Model层添加Required等

public class Student
    {
        public int Id { get; set; }
        
        [Display(Name = "姓名"),MaxLength(50,ErrorMessage = "名字的长度不能超过50个字符")]
        [Required(ErrorMessage = "请输入名字")]
        public string Name { get; set; }
        public ClassNameEnum ClassName { get; set; }
        
        [Required(ErrorMessage = "请输入邮箱地址")]
        [RegularExpression(
                @"^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,})$"
                ,ErrorMessage = "邮箱格式不正确")]
        [Display(Name = "邮箱地址")]
        public string Email { get; set; }
    }

第二步，在控制器中添加ModelSate.IsValed验证，并对控制器进行改造

public IActionResult Create(Student student)
        {
            if (ModelState.IsValid)
            { 
                Student newStudent = _studentRepository.Add(student);
                return View("Details", new { id = newStudent.Id} );
                
//                return RedirectToAction("Details", new {id = newStudent.Id}); 

            }

            return View();
        }

第三步，在视图文件中添加TagHelper用于表现层的验证和提示

@model Student
@{
    ViewBag.Title = "创建学生信息";
}
<form asp-controller="home"
      asp-action="create"
      method="post"
      class="mt-3">
    
    @* asp-validation-summary="All”：验证所有属性 *@
    <div class="text-danger" asp-validation-summary="All">div>


    <div class="form-group row">
       @* asp-for用于对验证属性进行绑定 *@
        <label asp-for="Name" class="col-sm-2 col-form-label">label>
        
        <div class="col-sm-10">
            <input asp-for="Name" class="form-control" placeholder="请输入名字"/>
          @* asp-validation-for="Name"用于验证后的结果显示 *@
            <span asp-validation-for="Name" class="text-danger">span>
        div>
        
    div>
    <div class="form-group row">
        <label asp-for="Email" class="col-sm-2 col-form-label">label>
        <div class="col-sm-10">
            <input asp-for="Email" class="form-control" placeholder="请输入邮箱"/>
            <span asp-validation-for="Email" class="text-danger">span>
        div>
    div>



    <div class="form-group row">
        <label asp-for="ClassName" class="col-sm-2 col-form-label">label>
        <div class="col-sm-10">
          @* asp-ietms对枚举类进行遍历 *@
            <select asp-for="ClassName"
                    asp-items="Html.GetEnumSelectList()"
                    class="custom-select mr-sm-2">
            select>
        div>
    div>

    <div class="col-sm-10">
        <button type="submit" class="btn-primary">创建button>
    div>
form>

附加：ClassNameEnum枚举类

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Threading.Tasks;

namespace StudentManagement.Models
{
    public enum ClassNameEnum
    {
        [Display(Name = "未选择")]
        None,
        [Display(Name = "一年级")]
        FirstGradel,
        [Display(Name = "二年级")]
        SecondGradel,
        [Display(Name = "三年级")]
        GradeThree 
    }
}

Select标签验证：

第一步：修改Model层

Students.cs

public class Student
    {
				// ?表示可空
        [Required]
        public ClassNameEnum? ClassName { get; set; }
        
    }

第二部，在View层中的Select标签中添加一个可空的option标签

<select asp-for="ClassName"
                    asp-items="Html.GetEnumSelectList()"
                    class="custom-select mr-sm-2">
                <option value="请选择">option>
            select>

第三部，修改之前的BUG

由于Detail的View可传入的对象为一个Model，所以需要将Controller里面的View方法改为RedirectToAction方法

HomeController.cs

public IActionResult Create(Student student)
        {
            if (ModelState.IsValid)
            { 
                Student newStudent = _studentRepository.Add(student);
//                return View("Details", new { id = newStudent.Id} );
                return RedirectToAction("Details", new {id = newStudent.Id});
            }
            return View();
        }