postgres entityframework foreignkey

     public class Model
     {
         [Key, Column("id"), DatabaseGenerated(DatabaseGeneratedOption.Identity)]
         public long Id { get; set; }
         [Column("create_time")]
         public DateTime CreTime { get; set; } = DateTime.Now;
         [Column("create_uid")]
         public long? CreUid { get; set; }
         [Column("update_time")]
         public DateTime? UpdTime { get; set; }
         [Column("update_uid")]
         public long? UpdUid { get; set; }
         [Column("remark")]
         public string Remark { get; set; }
         [Column("is_del")]
         public bool IsDel { get; set; } = false;
     }

     [Table("a_user_type")]
     public class UserCls
     {
         [Key, Column("id"), DatabaseGenerated(DatabaseGeneratedOption.None)]
         public long Id { get; set; }
         [Column("des")]
         public string Des { get; set; }
     }

     [Table("b_user")]
     public class User : Model
     {
         [Column("account"), Index(IsUnique = false)]
         public string Account { get; set; }
         [Column("passwd")]
         public string Passwd { get; set; }
         [Column("label")]
         public string Label { get; set; }
         [Column("cls_id"), ForeignKey("Cls")]
         public long? ClsId { get; set; }
         public virtual UserCls Cls { get; set; }
     }

以上数据库字段全部取小写，是因为postgres非常严格，驼峰式写法的sql要加双引号，非常麻烦。

mssqlserver 可以完全不用管，mysql只需注意表的名字小写即可，postgres连字段名都要特别注意。

     public class MesDbContext: DbContext
     {
         public MesDbContext():base("name=mes")
         {
             Database.SetInitializer(new MigrateDatabaseToLatestVersion<MesDbContext, MigrateConfig>());
         }

         public DbSet<User> Users { get; set; }
         public DbSet<UserCls> UserCls { get; set; }
     }

     public class MigrateConfig : DbMigrationsConfiguration<MesDbContext>
     {
         public MigrateConfig()
         {
             AutomaticMigrationsEnabled = true;
             AutomaticMigrationDataLossAllowed = true;
         }
     }

   <entityFramework>
     <defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework" />
     <providers>
       <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
       <provider invariantName="Npgsql" type="Npgsql.NpgsqlServices, EntityFramework6.Npgsql" />
     </providers>
   </entityFramework>
   

   <system.data>
     <DbProviderFactories>
       <!--  注意这里，安装程序包时，这里的配置并不会自动添加  -->
       <remove invariant="Npgsql" />
       <add name="Npgsql" invariant="Npgsql" description=".Net Framework Data Provider for Postgresql" type="Npgsql.NpgsqlFactory, Npgsql" />
     </DbProviderFactories>
   </system.data>
   

 <?xml version="1.0" encoding="utf-8"?>
 <packages>
   <package id="EntityFramework" version="6.2.0" targetFramework="net45" />
   <package id="EntityFramework6.Npgsql" version="3.1.1" targetFramework="net45" />
   <package id="Npgsql" version="3.2.5" targetFramework="net45" />
   <package id="System.Threading.Tasks.Extensions" version="4.4.0" targetFramework="net45" />
 </packages>