public class EfDbContext : DbContext
{
/// <summary>
/// 指定静态ILoggerFactory
/// </summary>
public static readonly ILoggerFactory MyLoggerFactory = LoggerFactory.Create(builder => { builder.AddConsole(); });
public EfDbContext() { }
public EfDbContext(DbContextOptions<EfDbContext> options)
: base (options)
{
}
private string Conn = null ;
public DbContext ToWriteOrRead( string conn)
{
Conn = conn;
return this ;
}
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
if (! optionsBuilder.IsConfigured)
{
optionsBuilder.UseLoggerFactory(MyLoggerFactory)
// .UseLazyLoadingProxies()
.UseSqlServer(Conn);
}
optionsBuilder.UseLoggerFactory(MyLoggerFactory);
}
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
#region MyRegion
{
// 指定主键
// modelBuilder.Entity<ClassGrade>().HasKey(a => a.Id);
/// //设置数据库架构
// modelBuilder.HasDefaultSchema("xl");
/// //表名、属性名映射
// modelBuilder.Entity<UserInfo>().ToTable("UserInfos", "Zhaoxi").Property(p => p.UserAge).HasColumnName("Age");
/// /设置联合主键
// modelBuilder.Entity<SysUserRoleMapping>().HasKey(p => new { p.SysUserId, p.SysRoleId });
/// /初始化数据
// modelBuilder.Entity<Company>().HasData(new List<Company>()
// {
// });
////// /表拆分:在数据库中是一整张表，在代码层面是多个实体与其对应；
// modelBuilder.Entity<SysLog>(dob =>
// {
// dob.ToTable("SysLogInfo");
// dob.Property(o => o.LogType).HasColumnName("LogType"); // 配置两个实体的相同属性映射到表的同一列
// dob.HasOne(o => o.SysLogDetail).WithOne().HasForeignKey<SysLog>(o => o.Id); ; // 配置两个实体的相同属性映射到表的同一列
// });
// modelBuilder.Entity<SysLogDetail>(dob =>
// {
// dob.ToTable("SysLogInfo");
// dob.Property(o => o.LogType).HasColumnName("LogType"); // 配置两个实体的相同属性映射到表的同一列
// });
}
// 设置一对多的关系
modelBuilder.Entity<Student>().HasOne(c => c.Class).WithMany(s => s.Students).HasForeignKey(b => b.ClassId);
/// /多对多关系
modelBuilder.Entity<MiddleStudentCourse>(eb =>
{
eb.HasOne(p => p.Course).WithMany(u => u.Students).HasForeignKey(u => u.CourseId);
eb.HasOne(p => p.Student).WithMany(r => r.Courses).HasForeignKey(s => s.StudentId);
});
modelBuilder.Entity <MiddleClassCourse>(eb => {
eb.HasOne(p => p.Course).WithMany(u => u.ClassStudents).HasForeignKey(u => u.CourseId);
eb.HasOne(p => p.Class).WithMany(r => r.Classs).HasForeignKey(s => s.ClassId);
});
#endregion
}
public DbSet<ClassGrade> Classs { get ; set ; }
public DbSet<Student> Students { get ; set ; }
public DbSet<Course> Courses { get ; set ; }
}
2.FreeSql的流程相对EF就简单许多了，不需要执行“Add-Migration”、“Update-Database”命令，运行时检查没有表自动创建，下面是FreeSql的DbContext类，与EF很相似。
public class FreeSqlContext: DbContext
{
public DbSet<Student> Students { get ; set ; }
public DbSet<Course> Courses { get ; set ; }
public DbSet<ClassGrade> ClassGrades { get ; set ; }
public DbSet<MiddleClassCourse> MiddleClassCourses { get ; set ; }
public DbSet<MiddleStudentCourse> MiddleStudentCourses { get ; set ; }
// 每个 DbContext 只触发一次
protected override void OnModelCreating(ICodeFirst codefirst)
{
codefirst.Entity <Student>(eb =>
{
eb.HasOne(a => a.Class).HasForeignKey(b => b.ClassId).WithMany(c => c.Students);
});
codefirst.Entity <MiddleStudentCourse>(eb =>
{
eb.HasOne(a => a.Student).WithMany(t => t.Courses).HasForeignKey(b => b.StudentId);
eb.HasOne(a => a.Course).WithMany(t => t.Students).HasForeignKey(a => a.CourseId);
});
codefirst.Entity <MiddleClassCourse>(eb =>
{
eb.HasOne(a => a.Course).WithMany(t => t.ClassStudents).HasForeignKey(a => a.CourseId);
eb.HasOne(a => a.Class).WithMany(t => t.Students).HasForeignKey(a => a.ClassId);
});
}
}
3.SqlSuger就更简单了，不需要配置DbContext，配置如下泛型类就可以了，T为实体类
public class SqlSugerContext<T>: SimpleClient<T> where T : class , new ()
{
public SqlSugerContext(SqlSugarClient context) : base (context) // 注意这里要有默认值等于null
{
context.CodeFirst.SetStringDefaultLength( 200 ).InitTables( typeof (T)); // 这样一个表就能成功创建了
}
}
public class ClassGradeService: SqlSugerContext<ClassGrade>
{
public ClassGradeService(SqlSugarClient context): base (context)
{
}
}
public class CourseService: SqlSugerContext<Course>
{
public CourseService(SqlSugarClient context) : base (context)
{
}
}
public class StudentService: SqlSugerContext<Student>
{
public StudentService(SqlSugarClient context) : base (context)
{
}
}
public class MiddleClassCourseCervice : SqlSugerContext<MiddleClassCourse>
{
public MiddleClassCourseCervice(SqlSugarClient context) : base (context)
{
}
}
public class MiddleStudentCourseService : SqlSugerContext<MiddleStudentCourse>
{
public MiddleStudentCourseService(SqlSugarClient context) : base (context)
{
}
}
三：配置声明
1.连接字符串（都实现了读写分离，由于只是测试，数据库主从都是同一个库，实际上不能这样写，不然没有读写分离的意义）：
" EfConnectionStrings " : {
" WriteConnection " : " Server=localhost;Database=DbEfCore;Trusted_Connection=True; " ,
" ReadConnectionList " : [
" Server=localhost;Database=DbEfCore;Trusted_Connection=True; "
]
},
" FreeSqlConnectionStrings " : " Server=localhost;Database=DbFreeSql;Trusted_Connection=True; " ,
" SqlSugerConnectionStrings " : " Server=localhost;Database=DbSqlSuger;Trusted_Connection=True; "
2.EF实现读写分离需要自行封装，另外两个只需要配置好连接字符就好了，下面是EF数据库读写分离的实现：
public enum WriteAndReadEnum
{
Write, // 主库操作
Read // 从库操作
}
public interface IDbContextFactory
{
public EfDbContext ConnWriteOrRead(WriteAndReadEnum writeAndRead);
}
public class DBConnectionOption
{
public string WriteConnection { get; set; }
public List<string> ReadConnectionList { get; set; }
}
public class DbContextFactory : IDbContextFactory
{
private readonly EfDbContext _Context = new EfDbContext();
private static int _iSeed = 0;
private readonly DBConnectionOption _readAndWrite = null;
public DbContextFactory(IOptionsMonitor<DBConnectionOption> options)
{
_readAndWrite = options.CurrentValue;
}
public EfDbContext ConnWriteOrRead(WriteAndReadEnum writeAndRead)
{
//判断枚举，不同的枚举可以创建不同的Context 或者更换Context链接；
switch (writeAndRead)
{
case WriteAndReadEnum.Write:
ToWrite();
break; //选择链接//更换_Context链接 //选择链接
case WriteAndReadEnum.Read:
ToRead();
break; //选择链接//更换_Context链接
default:
break;
}
return _Context;
}
/// <summary>
/// 更换成主库连接
/// </summary>
/// <returns></returns>
private void ToWrite()
{
string conn = _readAndWrite.WriteConnection;
_Context.ToWriteOrRead(conn);
}
/// <summary>
/// 更换成主库连接
///
/// ///策略---数据库查询的负载均衡
/// </summary>
/// <returns></returns>
private void ToRead()
{
var conn = this._readAndWrite.ReadConnectionList[_iSeed++ % this._readAndWrite.ReadConnectionList.Count];//轮询;
_Context.ToWriteOrRead(conn);
}
}
3.在ConfigureServices类中注入：
#region FreeSql // DbFreeSql
var freestr = Configuration.GetSection( " FreeSqlConnectionStrings " ).Value;
IFreeSql fsql = new FreeSql.FreeSqlBuilder()
.UseConnectionString(FreeSql.DataType.SqlServer, freestr)
.UseSlave(freestr) // 使用从数据库，支持多个
.UseAutoSyncStructure( true ) // 自动同步实体结构到数据库
.Build(); // 请务必定义成 Singleton 单例模式
services.AddSingleton<IFreeSql> (fsql);
services.AddFreeDbContext <FreeSqlContext>(options => options.UseFreeSql(fsql));
#endregion
#region SqlSuger // DbSqlSuger
var sugerstr = Configuration.GetSection( " SqlSugerConnectionStrings " ).Value;
services.AddScoped(options => new SqlSugarClient( new ConnectionConfig()
{
ConnectionString = sugerstr, // 连接符字串
DbType = DbType.SqlServer,
IsAutoCloseConnection = true ,
InitKeyType = InitKeyType.Attribute, // 从特性读取主键自增信息
SlaveConnectionConfigs = new List<SlaveConnectionConfig>() { // 使用从数据库，支持多个
new SlaveConnectionConfig() { HitRate= 10 , ConnectionString= sugerstr }
}
}));
services.AddScoped <ClassGradeService> ();
services.AddScoped <CourseService> ();
services.AddScoped <StudentService> ();
services.AddScoped <MiddleStudentCourseService> ();
services.AddScoped <MiddleClassCourseCervice> ();
#endregion
#region EfCore // DbEfCore
services.AddDbContext <EfDbContext>(options => options.UseSqlServer( " name=EfConnectionStrings:WriteConnection " ));
services.Configure <DBConnectionOption>(Configuration.GetSection( " EfConnectionStrings " )); // 注入多个链接
services.AddTransient<IDbContextFactory, DbContextFactory> ();
#endregion
四：总结
到此基本框架就搭建好了，下一篇将分别实现相同功能的三套API进行具体比较。
就目前来说，EF Core 最复杂学习成本高，同时Code First功能也是最强的，SqlSuger最简单容易上手，但是没有严格意义上的Code First，只是能够创建表而已。.Net 常用ORM框架对比：EF Core、FreeSql、SqlSuger
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