首先在EF 7代码中创建POCO类

问题描述

说我有三张桌子。设置，设施和设施在现有数据库中设置。样本数据：

 设置表
 
 ID名称值
 1 test1 true 
 2 test2 true 
 
设施表
 
 ID名称
 163 Demo1 
 164 Demo2 
 
 FacilitySettingOverride 
 FacilityId SettingId Value 
 163 2 False 
 164 1 False 
 164 2 False 
  

FacilitySettingOverride有两个外键--- FacilityId和SettingId。另外我想为FacilitySettingOverride创建一个复合键。

我只是不知道如何使它。我的主要代码

  [Table（Settings）] 
 public class设置
 {
 [Key] 
 public int Id {get;组; } 
 public string Name {get;组; } 
 public string Value {get;组; } 
 
 public FacilitySettingOverride FacilitySettingOverride {get;组; 
} 
 
 [表（设施）] 
 public class Facility 
 {
 [Key] 
 public int Id {get ;组; } 
 public string Name {get;组; } 
 public virtual ICollection< FacilitySettingOverride> FacilitySettingOverrides {get;组; } 
} 
 
 [Table（FacilitySettingOverride）] 
 public class FacilitySettingOverride 
 {
 [Key] 
 [ForeignKey（FacilityId ）] 
 public int FacilityId {get;组; } 
 
 public string Value {get;组; } 
 [ForeignKey（SettingId）] 
 public int SettingId {get;组; } 
 
 public virtual Facility Facility {get;组; } 
 public virtual设置设置{get;组; } 
  

我猜这是错误的。感谢您的帮助。

解决方案

查看您的数据和描述，设置和工具具有一对多关联到 FacilitySettingOverride 。所以设置不应该有一个属性...

  public FacilitySettingOverride FacilitySettingOverride {get;组; } 
  

...但是集合 FacilitySettingOverride

这应该是正确的类模型：

  [表（设置）] 
 public class设置
 {
 [Key] 
 public int Id {get;组; } 
 public string Name {get;组; } 
 public string Value {get;组; } 
 public virtual ICollection< FacilitySettingOverride> FacilitySettingOverrides {get;组; 
} 
 
 [表（设施）] 
 public class Facility 
 {
 [Key] 
 public int Id {get ;组; } 
 public string Name {get;组; } 
 public virtual ICollection< FacilitySettingOverride> FacilitySettingOverrides {get;组; } 
} 
 
 [Table（FacilitySettingOverride）] 
 public class FacilitySettingOverride 
 {
 [Key，Column（Order = 1）] 
 [ForeignKey（Facility）] 
 public int FacilityId {get;组; 
 
 [Key，Column（Order = 2）] 
 [ForeignKey（Setting）] 
 public int SettingId {get;组; } 
 
 public virtual Facility Facility {get;组; } 
 public virtual设置设置{get;组; } 
 public string Value {get;组; 
} 
  

KeyAttribute 和 ColumnAttribute （ [Key，Column（Order = 1）] ）用于复合主键。 / p>

这是EF创建的数据库模式：

Say I have three tables. Settings, Facilities and FacilitySettingOverride in an existing database. The sample data:

Settings table

ID   Name     Value
1    test1    true
2    test2    true

Facilities table

ID    Name
163   Demo1
164   Demo2

FacilitySettingOverride
FacilityId      SettingId   Value
163               2         False
164               1         False
164               2         False

FacilitySettingOverride has two foreign keys---FacilityId and SettingId. Also I want to make a composite key for FacilitySettingOverride.

I just don't know how to make it. My primary code.

[Table("Settings")]
public class Setting
{
    [Key]
    public int Id { get; set; }
    public string Name { get; set; }
    public string Value { get; set; }

    public FacilitySettingOverride FacilitySettingOverride { get; set; }
}

[Table("Facilities")]
public class Facility
{
    [Key]
    public int Id { get; set; }
    public string Name { get; set; }
    public  virtual ICollection<FacilitySettingOverride> FacilitySettingOverrides { get; set; }
}

[Table("FacilitySettingOverride")]
public class FacilitySettingOverride
{
    [Key]
    [ForeignKey("FacilityId")]
    public int FacilityId { get; set; }

    public string Value { get; set; }
    [ForeignKey("SettingId")]
    public int SettingId { get; set; }

    public virtual Facility Facility { get; set; }
    public virtual Setting Setting { get; set; }

I guess that it is wrong. Thanks for help.

解决方案

Looking at your data and description, both Settings and Facility have one-to-many associations to FacilitySettingOverride. So Setting shouldn't have a property ...

public FacilitySettingOverride FacilitySettingOverride { get; set; }

... but a collection of FacilitySettingOverrides, just as Facility has.

This should be the proper class model:

[Table("Settings")]
public class Setting
{
    [Key]
    public int Id { get; set; }
    public string Name { get; set; }
    public string Value { get; set; }
    public virtual ICollection<FacilitySettingOverride> FacilitySettingOverrides { get; set; }
}

[Table("Facilities")]
public class Facility
{
    [Key]
    public int Id { get; set; }
    public string Name { get; set; }
    public virtual ICollection<FacilitySettingOverride> FacilitySettingOverrides { get; set; }
}

[Table("FacilitySettingOverride")]
public class FacilitySettingOverride
{
    [Key, Column(Order = 1)]
    [ForeignKey("Facility")]
    public int FacilityId { get; set; }

    [Key, Column(Order = 2)]
    [ForeignKey("Setting")]
    public int SettingId { get; set; }

    public virtual Facility Facility { get; set; }
    public virtual Setting Setting { get; set; }
    public string Value { get; set; }
}

The combination of KeyAttribute and ColumnAttribute ([Key, Column(Order = 1)]) is used for composite primary keys.

This is the database schema EF creates from it:

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