c#实体转换工具AutoMapper的使用讲解和扩展

 

背景介绍：
1.在开发中，我们经常需要将实体查询出来的实体转换为页面展示实体，这个页面展示的实体，其实我们口中常说的DTO（Data Tranfer Object）
2.我们查询完数据库数据后，如何转换为DTO呢，抛开手写，就要使用到工具了，今天带来的是一款轻量级的实体转换工具：AutoMapper
3.备注一下，AutoMapper十分强大，自己之前也踩过一些坑，但是我自己平时开发是不使用这个玩意的，我自己写了一套实体转换和映射，但是不代表AutoMapper不好哈，大多数玩家还是可以直接拿来开箱即用的

 

好了，进入正题，直接上代码，注释都写明白了

 

使用：

            Mapper.Initialize(config =>
            {
                //默认是同名即转换
                var map = config.CreateMap();

                //通过表达式目录树来指定转换规则，下面的含义是：target中的PersonId属性，从source中的StudentId读取
                map.ForMember(p => p.PersonId, r => r.MapFrom(x => x.StudentId));
                //数据类型不同，也可以转换，只要允许，例如int可以放到string中，string也可以放到int中，但是string如果无法转换为数字，则会报错
                map.ForMember("PersonId", r => r.MapFrom("StudentId"));
            });
            var studentList = GetStudentList();
            var personList = Mapper.Map, List>(studentList);

扩展（大家懂得使用方法后可以自己扩展更多）：

using System;
using System.Collections.Generic;
using AutoMapper;

namespace TestAutomapper
{
    /// 

    /// AutoMapper扩展
    /// 
    public static class AutomapperExtension
    {
        /// 

        /// 创建映射关系，如果实体包含子实体，子实体也要创建映射关系
        /// 
        /// 
        /// 
        /// key是target属性名，value是source属性名（读取value列的填充到key列中）
        private static void CreateMap(Dictionary dicCustomerMapping)
        {
            Mapper.Initialize(config =>
            {
                var map = config.CreateMap();
                if (dicCustomerMapping != null)
                {
                    foreach (var dicItem in dicCustomerMapping)
                    {
                        map = map.ForMember(dicItem.Key, r => r.MapFrom(dicItem.Value));
                    }
                }
            });
        }

        /// 

        /// 创建映射关系，如果实体包含子实体，子实体也要创建映射关系
        /// 
        /// 
        /// 
        /// key是target属性名，value是source属性名（读取value列的填充到key列中）
        private static void CreateMap(Type sourceType, Type targetType, Dictionary dicCustomerMapping)
        {
            Mapper.Initialize(config =>
            {
                var map = config.CreateMap(sourceType, targetType);
                if (dicCustomerMapping != null)
                {
                    foreach (var dicItem in dicCustomerMapping)
                    {
                        map = map.ForMember(dicItem.Key, r => r.MapFrom(dicItem.Value));
                    }
                }
            });
        }

        /// 

        /// 转换核心方法
        /// 
        /// 
        /// 
        /// 
        /// 
        private static TTarget MapLingbug(TSource source)
        {
            return Mapper.Map(source);
        }

        /// 

        /// 实体转换
        /// 
        /// 
        /// 
        /// 
        /// 
        /// 
        public static TTarget MapTo(this TSource source, Dictionary dicCustomerMapping = null)
        {
            CreateMap(dicCustomerMapping);
            return MapLingbug(source);
        }

        /// 

        /// 实体包含子实体的转换，除了实体需要映射，子实体也需要映射
        /// 
        /// 
        /// 
        /// 
        /// 
        /// 
        /// 
        public static TTarget MapTo(this TSource source, Dictionary dicCustomerMapping, List>> childMapList)
        {
            CreateMap(dicCustomerMapping);
            childMapList.ForEach(r =>
            {
                CreateMap(r.Item1, r.Item2, r.Item3);
            });
            return MapLingbug(source);
        }

        /// 

        /// 集合转换
        /// 
        /// 
        /// 
        /// 
        /// 
        /// 
        public static List MapTo(this List sourceList, Dictionary dicCustomerMapping = null)
        {
            CreateMap(dicCustomerMapping);
            return MapLingbug, List>(sourceList);
        }

        /// 

        /// 数组转换
        /// 
        /// 
        /// 
        /// 
        /// 
        /// 
        public static TTarget[] MapTo(this TSource[] sourceArray, Dictionary dicCustomerMapping = null)
        {
            CreateMap(dicCustomerMapping);
            return MapLingbug(sourceArray);
        }
    }
}

 

测试扩展：

            var studentList = GetStudentList();
            var dicMapping = new Dictionary()
            {
                {"PersonId", "StudentId"},//将StudentId映射到PersonId
                {"AgeDes","Age" },//将int转换为string映射过去
                {"Age","ClassName" }//将string转换为int映射过去
            };
            var personList = studentList.MapTo(dicMapping);

 

实体类和初始化数据代码：

    public class Person
    {
        public int PersonId { get; set; }

        public string Name { get; set; }

        public int Age { get; set; }

        public string Sex { get; set; }

        public DateTime CreateDate { get; set; }

        public string AgeDes { get; set; }
    }
    
    public class Student
    {
        public int StudentId { get; set; }

        public string Name { get; set; }

        public int Age { get; set; }

        public string Sex { get; set; }

        public DateTime CreateDate { get; set; }

        public string ClassName { get; set; }

        public string TeacherName { get; set; }
    }
    
    private static List GetStudentList()
        {
            char a = '，';
            var names = "张三，李四，王五，赵六，田七".Split(a);
            var sexs = "男，女".Split(a);
            var classNames = "普通一班，奥赛二班，竞赛三班，报送四班".Split(a);
            var teacherNames = "张老师，王老师，李老师，孙老师".Split(a);

            var r = new Random();

            var list = new List();
            for (int i = 0; i < 100; i++)
            {
                var nameIndex = r.Next(names.Length);
                var sexIndex = r.Next(sexs.Length);
                var classNameIndex = r.Next(classNames.Length);
                var teacherNameIndex = r.Next(teacherNames.Length);

                list.Add(new Student()
                {
                    StudentId = i + 1,
                    Name = names[nameIndex],
                    Age = r.Next(15, 30),
                    Sex = sexs[sexIndex],
                    CreateDate = DateTime.Now,
                    //ClassName = classNames[classNameIndex],
                    ClassName = (i + 5).ToString(),
                    TeacherName = teacherNames[teacherNameIndex]
                });
            }

            return list;
        }

 

 

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