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使用EntityTpeConfiguration映射short[]

ef-fluent-api entity-framework c#

Dener · 技术社区 · 7 年前

有人能解释一下我应该如何使用数组或基元值列表映射实体吗 EntityTypeConfiguration . 我有以下实体和枚举:

public class PermissionForm
{
   public int Id {get; set;}

   public string Name {get; set;}

   public PermissionItem[] Permissions {get; set;}
}

public enum PermissionItem : short
{
   EDIT = 1,
   SHARE = 2,
   ADMIN = 3
}

| PermissionForm |
| -------------- |
| Id             |
| Name           |

|  PermissionForm_PermissionItems |
| ------------------------------- |
| PermissionFormId                |
| PermissionItem_Value            |

到目前为止,我得到了以下代码,但我认为它不太靠右:

public PermissionForMap()
{
    this.ToTable("PermissionForm").HasKey(p => p.Id);

    this.Property(p => p.Name).HasColumnName("Name").HasMaxLength(30);
    this.Map(map =>
    {
       map.ToTable("PermissionsFormPermissionItem");
       map.Requires(p => p.Id);
       map.Properties(p => p.PermissionItems);
    });
}

1 回复 | 直到 7 年前

Federico Dipuma 7 年前

`[Flags]`

支持场景的最有效方法是使用 Enum FlagsAttribute 在其上(这至少需要EntityFramework 5):

public class PermissionForm
{
   public int Id {get; set;}

   public string Name {get; set;}

   public PermissionItem Permissions {get; set;}
}

[Flags]
public enum PermissionItem : short
{
   EDIT = 1,
   SHARE = 2,
   ADMIN = 4 // note that each value must be a power of 2
}

不需要任何特定映射:

public PermissionForMap()
{
    this.ToTable("PermissionForm").HasKey(p => p.Id);

    this.Property(p => p.Name).HasColumnName("Name").HasMaxLength(30);
    this.Property(p => p.Permissions).HasColumnName("Permissions"); // this is redundant, it's just to replicate your behavior
}

& ( AND ) | ( OR ) , ^ ( XOR ) 和 ~ (complement)

这将简化模型,并避免使用另一个表(这也需要查询中的连接)。

实例

SHARE 许可:

var query = _dbContext.PermissionForms.Where(p => p.PermissionItem & PermissionItem.SHARE > 0);

如果使用EntityFramework 6.1+还可以使用内置方法 HasFlag :

var query = _dbContext.PermissionForms.Where(p => p.PermissionItem.HasFlag(PermissionItem.SHARE));

为实体设置多个权限:

var permission = new PermissionForm
{
    Name = "MyName",
    Permissions = PermissionItem.EDIT | PermissionItem. SHARE // this has EDIT and also SHARE
};

表映射

如果您真的想将关系映射到一个表(在我看来,这对于您的场景来说是无用且低效的),那么您需要创建一个类,该类作为一个实体由EntityFramework支持:

public class PermissionForm
{
   public PermissionForm()
   {
       Permissions = new HashSet<PermissionEntity>();
   }

   public int Id {get; set;}

   public string Name {get; set;}

   public virtual ICollection<PermissionEntity> Permissions {get; set;}
}

public class PermissionEntity
{
    public int PermissionFormId { get; set; }

    public PermissionItem PermissionItem { get; set; }

    public virtual PermissionForm PermissionForm { get; set; }
}

public enum PermissionItem : short
{
   EDIT = 1,
   SHARE = 2,
   ADMIN = 3
}

并将其映射为模型的任何其他导航属性:

public class PermissionForMap : EntityTypeConfiguration<PermissionForm>
{
    public PermissionForMap()
    {
        this.ToTable("PermissionForm").HasKey(p => p.Id);

        this.Property(p => p.Name).HasColumnName("Name").HasMaxLength(30);
        this.HasMany(p => p.Permissions) 
            .WithRequired(e => e.PermissionForm)
            .HasForeignKey(e => e.PermissionFormId);
    }
}

public class PermissionEntityMap : EntityTypeConfiguration<PermissionEntity>
{
    public PermissionEntityMap()
    {
        ToTable("PermissionEntities")
            .HasKey(e => new { e.PermissionFormId, e.PermissionItem }):
    }
}