EF Core Table Splitting - One table to multiple classes

问题

My table has four columns and I want to split it between multiple classes.

table1
 key
 col1
 col2
 col3
 col4

Class ClassA 
  key
  col1
  col2

class ClassB
   key
   col3
   col4

modelBuilder.Entity().ToTable("table1");
modelBuilder.Entity().ToTable("table1");

Currently it give me

System.InvalidOperationException: 'Cannot use table 'table1' for entity type 'ClassB' since it is being used for entity type 'ClassA'

Is it possible in EF Core?

Thanks

回答1:

You may need a relationship defined like the following based on to this MS docs:

modelBuilder.Entity<ClassA>()
    .HasOne(e => e.ClassB).WithOne(e => e.ClassA)
    .HasForeignKey<ClassB>(e => e.Key);
modelBuilder.Entity<ClassA>().ToTable("Products");
modelBuilder.Entity<ClassB>().ToTable("Products");

回答2:

You can define base class for ClassA and ClassB:

abstract class ClassBase
{
    public int Key { get; set; }
}

public class ClassA : ClassBase
{
    public int Col1 { get; set; }
    public int Col2 { get; set; }
}

public class ClassB : ClassBase
{
    public int Col3 { get; set; }
    public int Col4 { get; set; }
}

Then you can define following mapping:

    modelBuilder.Entity<ClassA>().HasBaseType<ClassBase>();
    modelBuilder.Entity<ClassB>().HasBaseType<ClassBase>();

This will create table columns:

Key
Col1 (nullable)
Col2 (nullable)
Col3 (nullable)
Col4 (nullable)
Discriminator

Discriminator column is for determining the type of entity. You can control this column by HasDiscriminator methods. Instead of defining entities as above, you can use, for example:

    modelBuilder.Entity<ClassBase>().HasDiscriminator<int>("ClassType")
                .HasValue<ClassA>(1)
                .HasValue<ClassB>(2);

来源：https://stackoverflow.com/questions/47686775/ef-core-table-splitting-one-table-to-multiple-classes

标签

ef-core-2.0

table-splitting