文章概述

本文使用ASP .NET Core的WEB API,构建一个RESTful风格的接口,使用Freesql访问MySQL数据库,实现二个表的简单博客,并集成AutoMapper。

接上一篇

Dto作用

当我们使用RESTful提供接口时,比如创建一个博客,修改一下博客内容时,他们的参数是有区别的。良好的设计应该是

创建一个博客

POST /api/blog
data:
{
"title": "string",
"content": "string"
}

修改一个博客内容

PUT /api/blog
data:
{
"blogId":"int",
"title": "string",
"content": "string"
}

但一个blog 实体如下

public class Blog
{
[Column(IsIdentity = true, IsPrimary = true)]
public int BlogId { get; set; }
public string Title { get; set; }
public string Content { get; set; }
public DateTime CreateTime { get; set; }
public virtual List<Post> Posts { get; set; }
}

如果我们以Blog作为controllers中的参数时

// POST api/blog
[HttpPost]
public void Post([FromBody] Blog blog)
{
blog.CreateTime=DateTime.Now;
_fsql.Insert<Blog>(blog).ExecuteAffrows();
}

这时修改swagger显示的默认参数是

{
"blogId": 0,
"title": "string",
"content": "string",
"createTime": "2019-06-30T07:33:05.524Z",
"posts": [
{
"postId": 0,
"replyContent": "string",
"blogId": 0,
"replyTime": "2019-06-30T07:33:05.524Z"
}
]
}

如果我们不传递createTime,会出现异常,应该createTime是DateTime,不能为null,只有DateTime?才能为null,有?为可空类型。

所以我们应该为POST方式传递过来时,新建一个实体类,我们称之为DTO(Data Transfer Object),即数据传输对象,因为createTime即使传递,后端为他赋了值,前台传了也无效。有了DTO,这样可让前端清楚他们应该传递的参数,而不会出现没有作用的参数。

在根目录创建Models/Blogs文件夹,在Blogs文件夹中创建

CreateBlogDto.cs

namespace RESTful.FreeSql.Models.Blogs
{
public class CreateBlogDto
{
public string Title { get; set; }
public string Content { get; set; }

}
}

UpdateBlogDto.cs

namespace RESTful.FreeSql.Models.Blogs
{
public class UpdateBlogDto
{
public int BlogId { get; set; }
public string Title { get; set; }
public string Content { get; set; }
}
}

有了Dto后,我们会发现了新的问题,往数据库插入时,往往使用了一些ORM,他们只支持原本的实体类,如Blog,Post。但不支持CreateBlogDto、UpdateBlogDto,我们可以手动,将一个类的值,赋值给另一个类。

CreateBlogDto createBlogDto = new CreateBlogDto()
{
Title = "我是title",
Content = "我是content"
};

Blog newBlog=new Blog()
{
Title = createBlogDto.Title,
Content = createBlogDto.Content
};

现在只是非常简单的二个属性,我们还能忍受,但如果是十个属性、而且有着大量的类与类之间的转换呢。这时修改AutoMapper就闪亮登场了。

AutoMapper

作用:A convention-based object-object mapper.

我们是在ASP .NET Core下使用AutoMapper 官网介绍,如何依赖注入中使用

Setup

先cd到dotnetcore-examples\asp.net-core-freesql\RESTful.FreeSql目录

PS > dotnet add package AutoMapper
PS > dotnet add package AutoMapper.Extensions.Microsoft.DependencyInjection --version 6.1.1

在StartUp.cs中的ConfigureServices配置如下

public void ConfigureServices(IServiceCollection services)
{
// .... Ignore code before this

//AddAutoMapper会去找继承Profile的类,这个只适用于继承Profile类在当前项目。
//services.AddAutoMapper(AppDomain.CurrentDomain.GetAssemblies());

//RESTful.Web.Core 字符串为项目名
//services.AddAutoMapper(Assembly.Load("RESTful.Web.Core"));
//或某一个类所在程序集
services.AddAutoMapper(typeof(Blog).Assembly);

// .... Ignore code after this
}

Adding Profiles

AutoMapper/BlogProfile.cs

using AutoMapper;
using RESTful.FreeSql.Domain;
using RESTful.FreeSql.Models.Blogs;

namespace RESTful.FreeSql.AutoMapper
{
public class BlogProfile : Profile
{
public BlogProfile()
{
CreateMap<CreateBlogDto, Blog>();
CreateMap<UpdateBlogDto, Blog>();
}
}
}

AutoMapper/BlogProfile.cs

using AutoMapper;
using RESTful.FreeSql.Domain;
using RESTful.FreeSql.Models.Blogs;

namespace RESTful.FreeSql.AutoMapper
{
public class PostProfile : Profile
{
public PostProfile()
{
CreateMap<CreatePostDto,Post>();
}
}
}

Models/Posts/SearchPostDto.cs根据博客id,得到分页的评论时,集成分页类

using RESTful.FreeSql.Web;

namespace RESTful.FreeSql.Models.Posts
{
public class SearchPostDto:PageDto
{
public int BlogId { get; set; }
}
}

Controlers/BlogController.cs文件中,注入IMapper,

using AutoMapper;
using Microsoft.AspNetCore.Mvc;
using System;
using System.Collections.Generic;
using RESTful.FreeSql.Domain;
using RESTful.FreeSql.Models.Blogs;
using RESTful.FreeSql.Web;

namespace RESTful.FreeSql.Controllers
{
[Route("api/[controller]")]
[ApiController]
public class BlogController : ControllerBase
{
// GET api/Blog

private readonly IFreeSql _fsql;
private readonly IMapper _mapper;
public BlogController(IFreeSql fsql, IMapper mapper)
{
_fsql = fsql;
_mapper = mapper;
}

/// <summary>
/// 博客列表页
/// </summary>
/// <param name="pageDto">分页参数</param>
/// <returns></returns>
[HttpGet]
public ActionResult<PagedResultDto<Blog>> Get([FromQuery]PageDto pageDto)
{
List<Blog> blogs = _fsql.Select<Blog>().OrderByDescending(r => r.CreateTime).Page(pageDto.PageNumber, pageDto.PageSize).ToList();
long count = _fsql.Select<Blog>().Count();
return new PagedResultDto<Blog>(count, blogs);
}

// GET api/blog/5
[HttpGet("{id}")]
public ActionResult<Blog> Get(int id)
{
// eg.1 return _fsql.Select<Blog>().Where(a => a.Id == id).ToOne();
// eg.2
return _fsql.Select<Blog>(id).ToOne();
}

// POST api/blog
[HttpPost]
public void Post([FromBody] CreateBlogDto createBlogDto)
{
Blog blog = _mapper.Map<Blog>(createBlogDto);
blog.CreateTime = DateTime.Now;
_fsql.Insert<Blog>(blog).ExecuteAffrows();
}

// PUT api/blog
[HttpPut]
public void Put([FromBody] UpdateBlogDto updateBlogDto)
{

//eg.1 更新指定列
//_fsql.Update<Blog>(updateBlogDto.BlogId).Set(a => new Blog()
//{
// Title = updateBlogDto.Title,
// Content = updateBlogDto.Content
//}).ExecuteAffrows();

//eg.2将这个实体更新到数据库中。当更新时,会把其他列的值,如CreateTime也更新掉。
//使用IgnoreColumns可忽略某一些列。

Blog blog = _mapper.Map<Blog>(updateBlogDto);
_fsql.Update<Blog>().SetSource(blog).IgnoreColumns(r => r.CreateTime).ExecuteAffrows();
}

// DELETE api/blog/5
[HttpDelete("{id}")]
public void Delete(int id)
{
_fsql.Delete<Blog>(new { BlogId = id }).ExecuteAffrows();
}
}
}

Controlers/BlogController.cs文件中,注入IMapper,

using FreeSql;
using Microsoft.AspNetCore.Mvc;
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using AutoMapper;
using RESTful.FreeSql.Domain;
using RESTful.FreeSql.Models.Posts;
using RESTful.FreeSql.Web;

namespace RESTful.FreeSql.Controllers
{
[Route("api/[controller]")]
[ApiController]
public class PostController : ControllerBase
{
// GET: api/Post
private readonly IFreeSql _fsql;
private readonly IMapper _mapper;
public PostController(IFreeSql fsql, IMapper mapper)
{
_fsql = fsql;
_mapper = mapper;
}

/// <summary>
/// 根据博客id、分页条件查询评论信息
/// </summary>
/// <param name="searchPostDto"></param>
/// <returns></returns>
[HttpGet]
public PagedResultDto<Post> Get(SearchPostDto searchPostDto)
{
ISelect<Post> selectPost = _fsql
.Select<Post>()
.Where(r => r.BlogId == searchPostDto.BlogId);

List<Post> posts = selectPost.OrderByDescending(r => r.ReplyTime)
.Page(searchPostDto.PageNumber, searchPostDto.PageSize)
.ToList();

long total = selectPost.Count();

return new PagedResultDto<Post>(total, posts);
}

// GET: api/Post/5
[HttpGet("{id}", Name = "Get")]
public Post Get(int id)
{
return _fsql.Select<Post>().Where(a => a.PostId == id).ToOne();
}

// POST: api/Post
[HttpPost]
public void Post([FromBody] CreatePostDto createPostDto)
{
Post post = _mapper.Map<Post>(createPostDto);
post.ReplyTime = DateTime.Now;
_fsql.Insert(post).ExecuteAffrows();
}


// DELETE: api/Post/
[HttpDelete("{id}")]
public async Task DeleteAsync(int id)
{
await _fsql.Delete<Post>(new Post { PostId = id }).ExecuteAffrowsAsync();
}
}
}

参考

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