[英]Entity Framework Core: FK with Different DataType than PK
運行時 :netcoreapp2.0
ASP.Net核心 :2.0.1
EF Core :2.0.1
Microsoft.EntityFrameworkCore.SqlServer :2.0.1
所以,我正在處理一個被許多服務使用的舊數據庫,原始創建者將一個表的PK定義為short,將該表的FK定義為int。 我可以處理這個案子嗎?
注意:此時更改列類型是不可行的。
考慮兩個類:
public class Database {
public short DatabaseId { get; set; }
public Database { get; set; }
}
public class Client {
public int ClientId { get; set; }
public int DatabaseId { get; set; }
public Database Database { get; set; }
}
我的第一次嘗試:
public int DatabaseId { get; set; }
[ForeignKey("DatabaseId")] public Database Database { get; set; }
投
System.InvalidOperationException: The relationship from 'Client.Database' to 'Database.Client' with foreign key properties {'DatabaseId' : int} cannot target the primary key {'DatabaseId' : short} because it is not compatible. Configure a principal key or a set of compatible foreign key properties for this relationship.
現在使用流暢的API:
modelBuilder.Entity<Client>(table => {
table.HasOne(p => p.Database)
.WithOne(i => i.Client)
.HasForeignKey<Client>(c => c.DatabaseId)
.HasPrincipalKey<Database>(d => d.DatabaseID);
});
嘗試定義陰影屬性失敗
modelBuilder.Entity<Client>(table => {
table.Property<int>("DatabaseId");
table.HasOne(p => p.Database)
.WithOne(i => i.Client)
.HasForeignKey("DatabaseId")
.HasPrincipalKey<Database>(d => d.DatabaseId);
});
投
System.InvalidOperationException: You are configuring a relationship between 'Client' and 'Database' but have specified a foreign key on 'DatabaseId'. The foreign key must be defined on a type that is part of the relationship.
好的,這次沒有影子屬性:
modelBuilder.Entity<Client>(table => {
table.HasOne(p => p.Database)
.WithOne(i => i.Client)
.HasForeignKey<Client>(c => c.DatabaseId)
.HasPrincipalKey<Database>(d => d.SQLDatabaseID);
});
投
System.InvalidOperationException: The types of the properties specified for the foreign key {'DatabaseId'} on entity type 'Client' do not match the types of the properties in the principal key {'DatabaseID'} on entity type 'Database'.
所以,然后我嘗試只更改實體類型,也許EF可以將int映射到int16。
public class Client {
public int ClientId { get; set; }
public short DatabaseId { get; set; } // <-- now a short
public Database Database { get; set; }
}
投
System.InvalidOperationException: An exception occurred while reading a database value for property 'Client.DatabaseId'. The expected type was 'System.Int16' but the actual value was of type 'System.Int32'. ---> System.InvalidCastException: Unable to cast object of type 'System.Int32' to type 'System.Int16'.
我開始覺得這是不可能的。
在EF Core 2.1中,您可以使用值轉換,即
entityBuilder.Property(c => c.Id).HasConversion<string>();
其中通用字符串是數據庫類型,目標是模型類型。 您可以在https://docs.microsoft.com/es-es/ef/core/modeling/value-conversions上進一步閱讀
您可以使用以下代碼來繞過實體框架生成的錯誤來定義外鍵
[Column(TypeName = "int")]
public short DatabaseId { get; set; }
但是一旦你運行遷移,你將收到此錯誤,這是由sql server生成的。
列'Databases.DatabaseId'與外鍵'FK_Clients_Databases_DatabaseId'中引用列'Clients.DatabaseId'的數據類型不同。
這很有道理。 您嘗試實現的內容在物理上是不可能的,因為SQL Server要求外鍵是相同的類型,否則您無法構建外鍵關系。
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