Entity Framework Core
Entity Framework (EF) Core 是轻量化、可扩展、开源和跨平台版的常用 Entity Framework 数据访问技术。
EF Core 可用作对象关系映射程序 (O/RM)，这可以实现以下两点：
使 .NET 开发人员能够使用 .NET 对象处理数据库。
无需再像通常那样编写大部分数据访问代码。
EF 支持以下模型开发方法：
- Database First:先有数据库，后有实体模型。从现有数据库生成模型。对模型手动编码，使其符合数据库。
- Code First：创建模型后，使用 EF 迁移从模型创建数据库。 模型发生变化时，迁移可让数据库不断演进。先有实体模型，后生成数据库
创建模型
通用模型
数据表，都会有主键字段。为了满足此需求，所以我们建立一个通用的泛型模型BaseEntity
/// <summary>
/// 通用基本模型
/// </summary>
/// <typeparam name="K">主键类型</typeparam>
public class BaseEntity<K>
{
/// <summary>
/// Id,主键
/// </summary>
public K Id { get; set; }
}
/// <summary>
/// 通用模型
/// </summary>
public class BaseEntity : BaseEntity<string>
{
}
为了让系统知道我们的Id字段是主键，我们增加了对通用模型的配置
EF可以有两种方法来配置实体，一种是使用数据批注(Attribute)
还有一种是Fluent API，就是通过代码来对模型配置
本示例使用Fluent API来配置
因为有些特殊情况是不能使用数据批注(Attribute)来满足要求
比如多主键，多外键，关联等情况。
/// <summary>
/// 默认实体配置
/// OnModelCreating
/// </summary>
/// <typeparam name="T"></typeparam>
/// <typeparam name="K"></typeparam>
public class BaseEntityTypeConfig<T, K> : IEntityTypeConfiguration<T>
where T : BaseEntity<K>
{
public virtual void Configure(EntityTypeBuilder<T> builder)
{
#region 主外键关系
builder.HasKey(k => k.Id);//设置主键
#endregion
#region 字段属性:最大长度,是否必需,默认值
#endregion
#region 备注
builder.Property(p => p.Id).HasComment("主键");//设置备注
#endregion
}
}
public class BaseEntityTypeConfig<T> : BaseEntityTypeConfig<T, string>, IEntityTypeConfiguration<T>
where T : BaseEntity
{
public override void Configure(EntityTypeBuilder<T> builder)
{
base.Configure(builder);
#region 主外键关系
#endregion
#region 字段属性:最大长度,是否必需,默认值
builder.Property(p => p.Id).HasMaxLength(50);//设置主键最大长度50
#endregion
#region 备注
#endregion
}
}
对于业务实体，一般我们又会有些其它通过字段，比如创建人，创建时间，修改人，修改时间，是否删除等公共字段
所以我们创建了BusEntity通用业务模型
/// <summary>
/// 业务实体基类
/// </summary>
/// <typeparam name="K">主键类型</typeparam>
public class BusEntity<K> : BaseEntity<K>
{
/// <summary>
/// 是否删除
/// </summary>
public bool Deleted { get; set; }
/// <summary>
/// 创建人
/// </summary>
public K CreateUserId { get; set; }
/// <summary>
/// 创建时间
/// </summary>
public DateTime CreateTime { get; set; }
/// <summary>
/// 修改人
/// </summary>
public K ModifyUserId { get; set; }
/// <summary>
/// 修改时间
/// </summary>
public DateTime ModifyTime { get; set; }
}
/// <summary>
/// 业务实体基类
/// </summary>
public class BusEntity : BusEntity<string>
{ }
对于基本业务实体基类用以下配置
/// <summary>
/// 默认实体配置
/// OnModelCreating
/// </summary>
/// <typeparam name="T"></typeparam>
/// <typeparam name="K"></typeparam>
public class BusEntityTypeConfig<T, K> : BaseEntityTypeConfig<T, K>, IEntityTypeConfiguration<T>
where T : BusEntity<K>
{
public override void Configure(EntityTypeBuilder<T> builder)
{
base.Configure(builder);
builder.HasQueryFilter(q => q.Deleted == false);//查询自动过滤已经删除的记录
#region 主外键关系
#endregion
#region 字段属性:最大长度,是否必需,默认值
builder.Property(p => p.Deleted).HasDefaultValue(false);//把是否删除设置为默认False
builder.Property(p => p.CreateUserId).HasMaxLength(50);//把创建人设置为默认值
builder.Property(p => p.ModifyUserId).HasMaxLength(50);//把修改人设置为默认值
builder.Property(p => p.CreateTime).HasDefaultValueSql("getdate()").ValueGeneratedOnAdd();//把创建时间设置默认值并在增加的时候更新值
builder.Property(p => p.ModifyTime).HasDefaultValueSql("getdate()").ValueGeneratedOnAddOrUpdate();//把修改时间设置默认值并在增加和修改的时候更新值
#endregion
#region 备注
builder.Property(p => p.Deleted).HasComment("是否删除");
builder.Property(p => p.CreateUserId).HasComment("创建人");
builder.Property(p => p.CreateTime).HasComment("创建时间");
builder.Property(p => p.ModifyUserId).HasComment("修改人");
builder.Property(p => p.ModifyTime).HasComment("修改时间");
#endregion
}
}
public class BusEntityTypeConfig<T> : BusEntityTypeConfig<T, string>, IEntityTypeConfiguration<T>
where T : BusEntity
{
public override void Configure(EntityTypeBuilder<T> builder)
{
base.Configure(builder);
#region 主外键关系
#endregion
#region 字段属性:最大长度,是否必需,默认值
builder.Property(p => p.Id).HasMaxLength(50);
#endregion
#region 备注
#endregion
}
}
业务模型
接下来我们有了通用模型基类。那么我们就可以来创建具体的业务模型
比如说我们的组织架构模型
我们使用两个局部类来定义，
第一个局部类定义基本属性
第二个局部类定义关联关系
然后对模型进行配置
/// <summary>
/// 组织架构
/// </summary>
public partial class Sys_Org : BusEntity
{
/// <summary>
/// 上级组织
/// </summary>
public string ParentId { get; set; }
/// <summary>
/// 名称
/// </summary>
public string Name { get; set; }
}
public partial class Sys_Org : BusEntity
{
/// <summary>
/// 上级组织
/// </summary>
public Sys_Org Parent { get; set; }
/// <summary>
/// 下级组织
/// </summary>
public List<Sys_Org> Childs { get; set; }
}
/// <summary>
/// 实体配置
/// OnModelCreating
/// </summary>
public class Sys_OrgTypeConfig : BusEntityTypeConfig<Sys_Org>, IEntityTypeConfiguration<Sys_Org>
{
public override void Configure(EntityTypeBuilder<Sys_Org> builder)
{
base.Configure(builder);
#region 主外键关系
builder.HasOne(p => p.Parent).WithMany(p => p.Childs).HasForeignKey(p => p.ParentId);
#endregion
#region 字段属性:最大长度,是否必需,默认值
builder.Property(p => p.Name).HasMaxLength(50).IsRequired();
#endregion
#region 备注
builder.Property(p => p.ParentId).HasComment("上级组织");
builder.Property(p => p.Name).HasComment("名称");
#endregion
}
}
/// <summary>
/// 系统用户
/// </summary>
public partial class Sys_User : BusEntity
{
/// <summary>
/// 工号、编码
/// </summary>
public string Code { get; set; }
/// <summary>
/// 名称
/// </summary>
public string Name { get; set; }
/// <summary>
/// 用户名
/// </summary>
public string UserName { get; set; }
/// <summary>
/// 密码
/// </summary>
public string Password { get; set; }
/// <summary>
/// 状态
/// </summary>
public string Status { get; set; }
/// <summary>
/// 所属组织
/// </summary>
public string OrgId { get; set; }
/// <summary>
/// 性别
/// </summary>
public string Sex { get; set; }
}
public partial class Sys_User : BusEntity
{
/// <summary>
/// 所属组织
/// </summary>
public Sys_Org Org { get; set; }
}
/// <summary>
/// 实体配置
/// OnModelCreating
/// </summary>
public class Sys_UserTypeConfig : BusEntityTypeConfig<Sys_User>, IEntityTypeConfiguration<Sys_User>
{
public override void Configure(EntityTypeBuilder<Sys_User> builder)
{
base.Configure(builder);
#region 主外键关系
builder.HasOne(p => p.Org).WithMany().HasForeignKey(p => p.OrgId);
#endregion
#region 字段属性:最大长度,是否必需,默认值
builder.Property(p => p.Code).HasMaxLength(50);
builder.Property(p => p.Name).HasMaxLength(50).IsRequired();
builder.Property(p => p.UserName).HasMaxLength(50).IsRequired();
builder.Property(p => p.Password).HasMaxLength(100).IsRequired();
builder.Property(p => p.Status).HasMaxLength(50).IsRequired();
builder.Property(p => p.OrgId).HasMaxLength(50);
builder.Property(p => p.Sex).HasMaxLength(50);
#endregion
#region 备注
builder.Property(p => p.Code).HasComment("编码");
builder.Property(p => p.Name).HasComment("名称");
builder.Property(p => p.UserName).HasComment("用户名");
builder.Property(p => p.Password).HasComment("密码");
builder.Property(p => p.Status).HasComment("状态");
builder.Property(p => p.OrgId).HasComment("所属组织");
builder.Property(p => p.Sex).HasComment("性别");
#endregion
}
}
创建数据库上下文Context
有了数据模型，接下来我们创建数据库上下文Context
OnConfiguring用来配置数据连接字符串
OnModelCreating是创建模型是对模型的配置
因为上面我们对每个模型都做了配置(实现了IEntityTypeConfiguration)
所以在这里我们只要把具体的配置配置应用到Context就行了
我们使用modelBuilder.ApplyConfigurationsFromAssembly
就可以把所有实现了IEntityTypeConfiguration的模型配置全部应用到数据库上下文
public class GDbContext : DbContext
{
/// <summary>
/// Context配置
/// </summary>
/// <param name="optionsBuilder"></param>
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
base.OnConfiguring(optionsBuilder);
optionsBuilder.UseSqlServer("Data Source=x.x.x.x;Initial Catalog=数据库名称;User Id=用户名;Password=密码;APP=系统名称;Pooling=true;");
}
/// <summary>
/// 模型创建
/// </summary>
/// <param name="modelBuilder"></param>
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.ApplyConfigurationsFromAssembly(this.GetType().Assembly);
}
/// <summary>
/// 组织架构
/// </summary>
public DbSet<Sys_Org> Sys_Org { get; set; }
/// <summary>
/// 用户
/// </summary>
public DbSet<Sys_User> Sys_User { get; set; }
}
所有代码结构如下
迁移数据库
专业名称叫迁移，通用解释就是把实体模型生成为数据表
我们在OnConfiguring中已经配置了使用SqlServer数据库（当然也支持其它所有类型数据库：如MySql,Oracle,Sqlite等其它数据库）
使用迁移，必需安装Microsoft.EntityFrameworkCore.Tools工具集
接下来我们在“程序包管理控制台”输入Add-Migration FirstInit (FirstInit:自定义名称)
系统会自动帮我们生成迁移代码
public partial class FirstInit : Migration
{
protected override void Up(MigrationBuilder migrationBuilder)
{
migrationBuilder.CreateTable(
name: "Sys_Org",
columns: table => new
{
Id = table.Column<string>(type: "nvarchar(50)", maxLength: 50, nullable: false, comment: "主键"),
ParentId = table.Column<string>(type: "nvarchar(50)", nullable: true, comment: "上级组织"),
Name = table.Column<string>(type: "nvarchar(50)", maxLength: 50, nullable: false, comment: "名称"),
Deleted = table.Column<bool>(type: "bit", nullable: false, defaultValue: false, comment: "是否删除"),
CreateUserId = table.Column<string>(type: "nvarchar(50)", maxLength: 50, nullable: true, comment: "创建人"),
CreateTime = table.Column<DateTime>(type: "datetime2", nullable: false, defaultValueSql: "getdate()", comment: "创建时间"),
ModifyUserId = table.Column<string>(type: "nvarchar(50)", maxLength: 50, nullable: true, comment: "修改人"),
ModifyTime = table.Column<DateTime>(type: "datetime2", nullable: false, defaultValueSql: "getdate()", comment: "修改时间")
},
constraints: table =>
{
table.PrimaryKey("PK_Sys_Org", x => x.Id);
table.ForeignKey(
name: "FK_Sys_Org_Sys_Org_ParentId",
column: x => x.ParentId,
principalTable: "Sys_Org",
principalColumn: "Id",
onDelete: ReferentialAction.Restrict);
});
migrationBuilder.CreateTable(
name: "Sys_User",
columns: table => new
{
Id = table.Column<string>(type: "nvarchar(50)", maxLength: 50, nullable: false, comment: "主键"),
Code = table.Column<string>(type: "nvarchar(50)", maxLength: 50, nullable: true, comment: "编码"),
Name = table.Column<string>(type: "nvarchar(50)", maxLength: 50, nullable: false, comment: "名称"),
UserName = table.Column<string>(type: "nvarchar(50)", maxLength: 50, nullable: false, comment: "用户名"),
Password = table.Column<string>(type: "nvarchar(100)", maxLength: 100, nullable: false, comment: "密码"),
Status = table.Column<string>(type: "nvarchar(50)", maxLength: 50, nullable: false, comment: "状态"),
OrgId = table.Column<string>(type: "nvarchar(50)", maxLength: 50, nullable: true, comment: "所属组织"),
Sex = table.Column<string>(type: "nvarchar(50)", maxLength: 50, nullable: true, comment: "性别"),
Deleted = table.Column<bool>(type: "bit", nullable: false, defaultValue: false, comment: "是否删除"),
CreateUserId = table.Column<string>(type: "nvarchar(50)", maxLength: 50, nullable: true, comment: "创建人"),
CreateTime = table.Column<DateTime>(type: "datetime2", nullable: false, defaultValueSql: "getdate()", comment: "创建时间"),
ModifyUserId = table.Column<string>(type: "nvarchar(50)", maxLength: 50, nullable: true, comment: "修改人"),
ModifyTime = table.Column<DateTime>(type: "datetime2", nullable: false, defaultValueSql: "getdate()", comment: "修改时间")
},
constraints: table =>
{
table.PrimaryKey("PK_Sys_User", x => x.Id);
table.ForeignKey(
name: "FK_Sys_User_Sys_Org_OrgId",
column: x => x.OrgId,
principalTable: "Sys_Org",
principalColumn: "Id",
onDelete: ReferentialAction.Restrict);
});
migrationBuilder.CreateIndex(
name: "IX_Sys_Org_ParentId",
table: "Sys_Org",
column: "ParentId");
migrationBuilder.CreateIndex(
name: "IX_Sys_User_OrgId",
table: "Sys_User",
column: "OrgId");
}
protected override void Down(MigrationBuilder migrationBuilder)
{
migrationBuilder.DropTable(
name: "Sys_User");
migrationBuilder.DropTable(
name: "Sys_Org");
}
}
更新到数据库
我们通过Update-Database命令更新到数据库
生成SQL脚本更新到生产数据库
有时候我们系统已经在运行了。开始也不可能直接连接生产数据库
那么我们修改了模型，可以通过生成SQL脚本，来更新数据库
#起始迁移点(没有写0)
#结束迁移点
Script-Migration -From 0 -To 20210225022927_FirstInit
IF OBJECT_ID(N'[__EFMigrationsHistory]') IS NULL
BEGIN
CREATE TABLE [__EFMigrationsHistory] (
[MigrationId] nvarchar(150) NOT NULL,
[ProductVersion] nvarchar(32) NOT NULL,
CONSTRAINT [PK___EFMigrationsHistory] PRIMARY KEY ([MigrationId])
);
END;
GO
BEGIN TRANSACTION;
GO
CREATE TABLE [Sys_Org] (
[Id] nvarchar(50) NOT NULL,
[ParentId] nvarchar(50) NULL,
[Name] nvarchar(50) NOT NULL,
[Deleted] bit NOT NULL DEFAULT CAST(0 AS bit),
[CreateUserId] nvarchar(50) NULL,
[CreateTime] datetime2 NOT NULL DEFAULT (getdate()),
[ModifyUserId] nvarchar(50) NULL,
[ModifyTime] datetime2 NOT NULL DEFAULT (getdate()),
CONSTRAINT [PK_Sys_Org] PRIMARY KEY ([Id]),
CONSTRAINT [FK_Sys_Org_Sys_Org_ParentId] FOREIGN KEY ([ParentId]) REFERENCES [Sys_Org] ([Id]) ON DELETE NO ACTION
);
DECLARE @defaultSchema AS sysname;
SET @defaultSchema = SCHEMA_NAME();
DECLARE @description AS sql_variant;
SET @description = N'主键';
EXEC sp_addextendedproperty 'MS_Description', @description, 'SCHEMA', @defaultSchema, 'TABLE', N'Sys_Org', 'COLUMN', N'Id';
SET @description = N'上级组织';
EXEC sp_addextendedproperty 'MS_Description', @description, 'SCHEMA', @defaultSchema, 'TABLE', N'Sys_Org', 'COLUMN', N'ParentId';
SET @description = N'名称';
EXEC sp_addextendedproperty 'MS_Description', @description, 'SCHEMA', @defaultSchema, 'TABLE', N'Sys_Org', 'COLUMN', N'Name';
SET @description = N'是否删除';
EXEC sp_addextendedproperty 'MS_Description', @description, 'SCHEMA', @defaultSchema, 'TABLE', N'Sys_Org', 'COLUMN', N'Deleted';
SET @description = N'创建人';
EXEC sp_addextendedproperty 'MS_Description', @description, 'SCHEMA', @defaultSchema, 'TABLE', N'Sys_Org', 'COLUMN', N'CreateUserId';
SET @description = N'创建时间';
EXEC sp_addextendedproperty 'MS_Description', @description, 'SCHEMA', @defaultSchema, 'TABLE', N'Sys_Org', 'COLUMN', N'CreateTime';
SET @description = N'修改人';
EXEC sp_addextendedproperty 'MS_Description', @description, 'SCHEMA', @defaultSchema, 'TABLE', N'Sys_Org', 'COLUMN', N'ModifyUserId';
SET @description = N'修改时间';
EXEC sp_addextendedproperty 'MS_Description', @description, 'SCHEMA', @defaultSchema, 'TABLE', N'Sys_Org', 'COLUMN', N'ModifyTime';
GO
CREATE TABLE [Sys_User] (
[Id] nvarchar(50) NOT NULL,
[Code] nvarchar(50) NULL,
[Name] nvarchar(50) NOT NULL,
[UserName] nvarchar(50) NOT NULL,
[Password] nvarchar(100) NOT NULL,
[Status] nvarchar(50) NOT NULL,
[OrgId] nvarchar(50) NULL,
[Sex] nvarchar(50) NULL,
[Deleted] bit NOT NULL DEFAULT CAST(0 AS bit),
[CreateUserId] nvarchar(50) NULL,
[CreateTime] datetime2 NOT NULL DEFAULT (getdate()),
[ModifyUserId] nvarchar(50) NULL,
[ModifyTime] datetime2 NOT NULL DEFAULT (getdate()),
CONSTRAINT [PK_Sys_User] PRIMARY KEY ([Id]),
CONSTRAINT [FK_Sys_User_Sys_Org_OrgId] FOREIGN KEY ([OrgId]) REFERENCES [Sys_Org] ([Id]) ON DELETE NO ACTION
);
DECLARE @defaultSchema AS sysname;
SET @defaultSchema = SCHEMA_NAME();
DECLARE @description AS sql_variant;
SET @description = N'主键';
EXEC sp_addextendedproperty 'MS_Description', @description, 'SCHEMA', @defaultSchema, 'TABLE', N'Sys_User', 'COLUMN', N'Id';
SET @description = N'编码';
EXEC sp_addextendedproperty 'MS_Description', @description, 'SCHEMA', @defaultSchema, 'TABLE', N'Sys_User', 'COLUMN', N'Code';
SET @description = N'名称';
EXEC sp_addextendedproperty 'MS_Description', @description, 'SCHEMA', @defaultSchema, 'TABLE', N'Sys_User', 'COLUMN', N'Name';
SET @description = N'用户名';
EXEC sp_addextendedproperty 'MS_Description', @description, 'SCHEMA', @defaultSchema, 'TABLE', N'Sys_User', 'COLUMN', N'UserName';
SET @description = N'密码';
EXEC sp_addextendedproperty 'MS_Description', @description, 'SCHEMA', @defaultSchema, 'TABLE', N'Sys_User', 'COLUMN', N'Password';
SET @description = N'状态';
EXEC sp_addextendedproperty 'MS_Description', @description, 'SCHEMA', @defaultSchema, 'TABLE', N'Sys_User', 'COLUMN', N'Status';
SET @description = N'所属组织';
EXEC sp_addextendedproperty 'MS_Description', @description, 'SCHEMA', @defaultSchema, 'TABLE', N'Sys_User', 'COLUMN', N'OrgId';
SET @description = N'性别';
EXEC sp_addextendedproperty 'MS_Description', @description, 'SCHEMA', @defaultSchema, 'TABLE', N'Sys_User', 'COLUMN', N'Sex';
SET @description = N'是否删除';
EXEC sp_addextendedproperty 'MS_Description', @description, 'SCHEMA', @defaultSchema, 'TABLE', N'Sys_User', 'COLUMN', N'Deleted';
SET @description = N'创建人';
EXEC sp_addextendedproperty 'MS_Description', @description, 'SCHEMA', @defaultSchema, 'TABLE', N'Sys_User', 'COLUMN', N'CreateUserId';
SET @description = N'创建时间';
EXEC sp_addextendedproperty 'MS_Description', @description, 'SCHEMA', @defaultSchema, 'TABLE', N'Sys_User', 'COLUMN', N'CreateTime';
SET @description = N'修改人';
EXEC sp_addextendedproperty 'MS_Description', @description, 'SCHEMA', @defaultSchema, 'TABLE', N'Sys_User', 'COLUMN', N'ModifyUserId';
SET @description = N'修改时间';
EXEC sp_addextendedproperty 'MS_Description', @description, 'SCHEMA', @defaultSchema, 'TABLE', N'Sys_User', 'COLUMN', N'ModifyTime';
GO
CREATE INDEX [IX_Sys_Org_ParentId] ON [Sys_Org] ([ParentId]);
GO
CREATE INDEX [IX_Sys_User_OrgId] ON [Sys_User] ([OrgId]);
GO
INSERT INTO [__EFMigrationsHistory] ([MigrationId], [ProductVersion])
VALUES (N'20210225022927_FirstInit', N'5.0.3');
GO
COMMIT;
GO
这样的话。就只要把这个脚本放到生产环境去运行，
那么得到的结果也是和Update-Database结果是一样的