asp.net core EF code first

 

以连接mysql数据库为例

一 安装组件

microsoft.entityframeworkcore

microsoft.entityframeworkcore.relational

microsoft.entityframeworkcore.tools

mysqlconnector

pomelo.entityframeworkcore.mysql

 

二 新增mysqldbcontext,继承自dbcontext,并新增一个数据库表实体article

　　[table("articles")]
    public class article
    {
        /// <summary>
        /// 主键id
        /// </summary>
        [key]
        public string id { get; set; }

        /// <summary>
        /// 标题
        /// </summary>
        public string title { get; set; }

        /// <summary>
        /// 内容
        /// </summary>
        [maxlength(255)]
        public string content { get; set; }

        /// <summary>
        /// 创建时间
        /// </summary>
        public datetime createddt { get; set; }

        /// <summary>
        /// 修改时间
        /// </summary>
        public datetime modifieddt { get; set; }
    }


    public class mysqldbcontext : dbcontext
    {
        public mysqldbcontext(dbcontextoptions<mysqldbcontext> options) : base(options) { }

        public dbset<article> articlesets { get; set; }

        //...
    }

　　

三 appsettings配置数据库连接字符串,并在startup.cs中添加服务

 

 startup.cs:

services.adddbcontext<mysqldbcontext>(options => options.usemysql(configuration.getconnectionstring("mysql")));

　注:字符串连接名称"mysql"与appsettings中配置的名称对应.

 

三 code first方式创建数据库

1.程序包管理控制台pm命令

1 remove-migrations
2 add-migrations my-gration
3 update-database

2.donet命令行

1 dotnet ef migrations remove
2 dotnet ef migrations add my-gration
3 dotnet ef database update

3.代码内执行创建数据库的代码(ensurecreated)

新增dbcontextextension扩展类:

1 public static iwebhost ensurecreateddb<tcontext>(this iwebhost host) where tcontext : dbcontext
2 {
3     using (var scope = host.services.createscope())
4     {
5     var context = scope.serviceprovider.getservice<tcontext>();
6     context.database.ensurecreated();
7     }
8     return host;
9 }

在program.cs中调用该扩展方法:

1 public static void main(string[] args)
2 {
3     createwebhostbuilder(args).build()
4     .ensurecreateddb<mysqldbcontext>()  //调用扩展方法
5     .run();
6 }

 

四 使用ef进行增删改查

 1     [apicontroller]
 2     [route("api-hd/article")]
 3     public class articlecontroller : controllerbase
 4     {
 5         private mysqldbcontext _dbcontext;
 6 
 7         public articlecontroller(mysqldbcontext dbcontext)
 8         {
 9             _dbcontext = dbcontext;
10         }
11 
12         /// <summary>
13         /// 新增文章
14         /// </summary>
15         /// <param name="title"></param>
16         /// <param name="content"></param>
17         /// <returns></returns>
18         [allowanonymous]
19         [httppost]
20         [route("")]
21         public async task<bool> add(string title, string content)
22         {
23             var newarticle = new article()
24             {
25                 id = guid.newguid().tostring(),
26                 title = title,
27                 content = content,
28                 createddt = datetime.now,
29                 modifieddt = datetime.now,
30             };
31             await _dbcontext.addasync(newarticle);
32             await _dbcontext.savechangesasync();
33             return true;
34         }
35 
36         /// <summary>
37         /// 根据id查询文章
38         /// </summary>
39         /// <param name="id"></param>
40         /// <returns></returns>
41         [allowanonymous]
42         [httpget]
43         [route("{id}")]
44         public async task<article> getbyid(string id)
45         {
46             var data = await _dbcontext.articlesets.findasync(id);
47             return data;
48         }
49 
50         /// <summary>
51         /// 更新文章标题
52         /// </summary>
53         /// <param name="id"></param>
54         /// <param name="title"></param>
55         /// <returns></returns>
56         [allowanonymous]
57         [httpput]
58         [route("")]
59         public async task<bool> update(string id, string title)
60         {
61             var existarticle = await _dbcontext.articlesets.findasync(id);
62             if (existarticle == null)
63             {
64                 return false;
65             }
66 
67             existarticle.title = title;
68             //_dbcontext.update(existarticle);
69             await _dbcontext.savechangesasync();
70             return true;
71         }
72 
73         /// <summary>
74         /// 根据id删除文章
75         /// </summary>
76         /// <param name="id"></param>
77         /// <returns></returns>
78         [allowanonymous]
79         [httpdelete]
80         [route("{id}")]
81         public async task<bool> delete(string id)
82         {
83             var existarticle = await _dbcontext.articlesets.findasync(id);
84             if (existarticle == null)
85             {
86                 return false;
87             }
88 
89             _dbcontext.remove(existarticle);
90             await _dbcontext.savechangesasync();
91             return true;
92         }
93         
94     }