netcore使用EFcore(第一个实例)

 

说明:搭建netcore 使用efcore入门教程,跟着这个教程,傻瓜都可以成功!O(∩_∩)O哈哈~,咱们开始吧;

首先介绍下环境:

  vs2017,

  netcore2.2,

  EntityFramework6

  测试场景:Mysql,SqlServer

一、创建netcore模板项目

这个就不用多说了,创建完成看下版本:

 

二、引用EF Core

有的博主写的这样引用:Install-Package Microsoft.EntityFrameworkCore.Sqlite –Pre

但是,遗憾的是,报错了:

 

 然后我自己引用了以包,OK

为了方便复制,我直接复制出来:

1.Microsoft.EntityFrameworkCore
2.Install-Package Microsoft.EntityFrameworkCore.Sqlite
3.Install-Package Microsoft.EntityFrameworkCore.Design
4.Install-Package Microsoft.EntityFrameworkCore.Tools

 

 项目结构如下:

 

 三、创新测试的实体类

我这边创建了一个DBModel文件夹,然后分别创建了三个类:

OrderInfo.cs,

Passenger.cs,

Address.cs

为什么要创建这么几个呢:因为后续会设计到表之间关联关系,主键,外键,引用等等,当然,本文主要是入门,后面的文章会详细讲解;

(PS:关系:一个OrderInfo有一个Passenger和一个Address,一个Passenger又可以有多个OrderInfo和一个Address);

强调:需要引用MySql.Data.EntityFrameworkCore

OrderInfo.cs 

[MySqlCharset("utf8mb4")] //字符集,需要引用MySql.Data.EntityFrameworkCore
[MySqlCollation("utf8mb4_general_ci")] //排序规则
[Table("orderinfo", Schema = "manager")]
public class OrderInfo {

[JsonProperty("id")]
[Required]
[Column("id", TypeName = "int(11)")]
public int Id { get; set; }

/// <summary>
/// 订单Id
/// </summary>
[JsonProperty("order_id")]
[Required]
[Column("order_id", TypeName = "int(11)")]
public int OrderId { get; set; }

[JsonProperty("passengerid")]
[Column("passenger_id",TypeName ="int(11)")]
public int PassengerId { get; set; }

 

[JsonProperty("addressid")]
[Column("address_id", TypeName = "int(11)")]
public int AddressId { get; set; }

/// <summary>
/// 订单价格
/// </summary>
[StringLength(maximumLength: 100)]
[Column("price")]
public string Price { get; set; }

/// <summary>
/// 订单客人信息
/// </summary>
[ForeignKey("PassengerId")]
public Passenger OrderForPassenger { get; set; }

///// <summary>
///// 订单地址信息
///// </summary>
//[InverseProperty("OrderInfos")]
//public Address OrderForAddress { get; set; }

 

  

  

Passenger.cs

 [MySqlCharset("utf8mb4")] //字符集,需要引用MySql.Data.EntityFrameworkCore
    [MySqlCollation("utf8mb4_general_ci")] //排序规则
    [Table("passenger", Schema = "manager")]
    public class Passenger {

        [JsonProperty("id")]
        [Column("id", TypeName = "int(10)")]
        public int Id { get; set; }

        [JsonProperty("passenger_id")]
        [Column("passengerid",TypeName ="int(11)")]
        public int PassengerId { get; set; }

        [JsonProperty("passengername")]
        public string PassengerName { get; set; }

        [InverseProperty("OrderForPassenger")]
        public List<OrderInfo> OrderInfos { get; set; }

        //[InverseProperty("Passengers")]
        //public Address PssengerForAddress { get; set; }
    }

 

  

 Address.cs

 [MySqlCharset("utf8mb4")] //字符集,需要引用MySql.Data.EntityFrameworkCore
    [MySqlCollation("utf8mb4_general_ci")] //排序规则
    [Table("address", Schema = "manager")]
    public class Address {

        [JsonProperty("id")]
        [Required]
        public int Id { get; set; }

        [JsonProperty("province")]
        [StringLength(maximumLength: 256)]
        public string Province { get; set; }

        [JsonProperty("city")]
        [StringLength(maximumLength: 256)]
        public string City { get; set; }

        [JsonProperty("area")]
        [StringLength(maximumLength: 256)]
        public string Area { get; set; }

        [JsonProperty("street")]
        [StringLength(maximumLength:256)]
        public string Street { get; set; }
    }

 

  

 四、创建一个DataDBContext.cs类,代码如下

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

        }
        /// <summary>
        /// 订单
        /// </summary>
        public DbSet<OrderInfo> OrderInfos { get; set; }
        /// <summary>
        /// 乘客
        /// </summary>
        public DbSet<Passenger> Passengers { get; set; }

        /// <summary>
        /// 地址
        /// </summary>
        public DbSet<Address> Addresses { get; set; }
    }

 

 五、创建数据库初始化和连接

为了方便测试,将数据库连接配置放在了appsettings.json文件中了。配置文件内容如下:

 

{
  "Logging": {
    "LogLevel": {
      "Default": "Warning"
    }
  },
  "AllowedHosts": "*",
  "ConnectionSetting": {
    "UserConnectionString": "server=localhost;userid=root;pwd=123456;port=3306;database=manager",
    "ReadConnectionString": "server=localhost;userid=root;pwd=123456;port=3306;database=manager",
    "DbType": 0 //数据库类型
  }
}

 

在StartUp.cs中注册连接:

  services.AddDbContext<DataDBContext>(optionsBuilder => {
                var dataAppSetting = Configuration.GetSection("ConnectionSetting").Get<ConnectionSetting>();
                if (dataAppSetting == null) {
                    throw new Exception("未配置数据库连接");
                }

                switch (dataAppSetting.DbType) {
                    case 1:
                        //server连接,EnableRetryOnFailure表示失败支持重试;
                        optionsBuilder.UseSqlServer(dataAppSetting.UserConnectionString, option => option.EnableRetryOnFailure());
                        break;
                    default:
                        optionsBuilder.UseMySQL(dataAppSetting.UserConnectionString);
                        break;
                }
            });

 

 这里可能有朋友会问一下,万一数据库没有创建怎么办?

所以,这里Configure方法加一下内容

context.Database.EnsureCreated();//数据库不存在的话,会自动创建

 

六、打开对应文件目录,执行

打开文件夹的命令行,

输入

  dotnet ef migrations add MyFirstMigration

  dotnet ef database update

这样我们就创建好了数据库。更多命令请 dotnet ef -h

 

可以看到,里面其实是执行了创建数据库表的sql语句! 

那我,我们来看一下我数据库,结果如下:

有的朋友可能会问,为啥多了一个表:“_efmigrationshistory”,故名思义,这个表示执行操作的记录,因为可能对表增加字段,修改字段,删除字段等等;

当然只是一个记录:

 

 

运行完成之后,我们会发现,我们会多一个Migrations文件夹

 

里面的内容是什么呢,大家可以打开看看,下面是我的部分截图:

 

 可以看到,这些都是我们之前创建实体时的一些属性,如果是第一次尝试的朋友也没有必要设置这么多。

七、测试效果 

简单写了个demo测试效果

 

 话不多说,直接上代码:

Index.cshtml

@model IEnumerable<EfCoreDemo.DbModel.Address>

@{
    ViewBag.Title = "地址";
}
<table class="table">
    <tr>
        <th>Id</th>
        <th></th>
        <th></th>
        <th></th>
        <th>街道详细地址</th>
    </tr>

    @foreach (var item in Model) {
    <tr>
        <td>
            @Html.DisplayFor(modelItem => item.Id)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Province)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.City)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Area)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Street)
        </td>
    </tr>
    }
</table>

 

AddAddress.cshtml

@model EfCoreDemo.DbModel.Address
@{
    ViewData["Title"] = "Address";
}
<form asp-controller="Address" asp-action="AddAddress" method="post">
    <div class="form-group">
        <label asp-for="Province" class="col-md-2 control-label">省:</label>
        <div class="col-md-10">
            <input class="form-control" asp-for="Province" />
            <span asp-validation-for="Province" class="text-danger"></span>
        </div>
        <label asp-for="City" class="col-md-2 control-label">市:</label>
        <div class="col-md-10">
            <input class="form-control" asp-for="City" />
            <span asp-validation-for="City" class="text-danger"></span>
        </div>
        <label asp-for="Area" class="col-md-2 control-label">区:</label>
        <div class="col-md-10">
            <input class="form-control" asp-for="Area" />
            <span asp-validation-for="Area" class="text-danger"></span>
        </div>
        <label asp-for="Street" class="col-md-2 control-label">街道门牌号:</label>
        <div class="col-md-10">
            <input class="form-control" asp-for="Street" />
            <span asp-validation-for="Street" class="text-danger"></span>
        </div>
        <div class="col-md-offset-2 col-md-10">
            <input type="submit" value="保存" class="btn btn-success" />
        </div>
    </div>
</form>

 

AddressController.cs

 

 public class AddressController : Controller
    {
        private DataDBContext _context;

        public AddressController(DataDBContext context) {
            _context = context;
        }
        public IActionResult Index()
        {
            return View(_context.Addresses.ToList());
        }


        public IActionResult AddAddress() {
            return View();
        }

        [HttpPost]
        [ValidateAntiForgeryToken]
        public IActionResult AddAddress(Address address) {
            if (ModelState.IsValid) {
                _context.Addresses.Add(address);
                _context.SaveChanges();

                return RedirectToAction("Index");
            }

            return View(address);
        }

 

运行效果:

 

 

至此,初级版本搭建成功,且运行成功;

 

后记:本文主要是记录一下netcore怎么搭建efcore,只属于基础,自己学习的过程中也方便跟大家一起探讨,我们使用数据库的时候,不可能只有单独的几张表,

一般都会有主键,外键,索引,组合索引等等,

或者对表的操作,删除,修改,新增字段等等;

后续会继续更新更多的efcore的东西,如有问题,欢迎一起讨论。

 感谢以下文章提供的启发:

参考博客:https://www.cnblogs.com/liangxiaofeng/p/5806347.html

参考文档:https://docs.microsoft.com/zh-cn/ef/core/get-started/netcore/new-db-sqlite

 

posted @ 2019-07-10 20:49  明&天  阅读(13320)  评论(8编辑  收藏