Multi level Inheritence in EF Core from existing entity

Question

I have below model structure in EF core Code first approach.

public abstract class  BaseModel
{
    [Key]
    public string Id { get; set; }
    public DateTime LastUpdatedDate { get; set; }
}


public class Company  :BaseModel
{
     
    public string Name { get; set; }
    public string Address { get; set; }
}

public class CompanyLog :Company
{
     
    public string LogId { get; set; }
    public DateTime LogDate { get; set; }
}

and DB Context is
public class MyDbContext : DbContext
{
     public DbSet Company { get; set; }
     public DbSet CompanyLog { get; set; }
}

But after DB migration, CompanyLog table is getting created with only its own properties, but not with base table properties. How can I acheive this? After the db migration, database table structure expectation is

CREATE TABLE dbo."Company"
(
    Id text  NOT NULL,
    LastUpdatedDate TimeStamp, 
    Name text, 
    Address text, 
)
CREATE TABLE dbo."CompanyLog"
(
    Id text  NOT NULL,
    LastUpdatedDate TimeStamp, 
    Name text, 
    Address text, 
    LogId text   NULL,
    LogDate TimeStamp,  
)

user_5202563 · Answer

CompanyLog table is getting created with only its own properties, but not with base table properties

It's because EF Core considers Company and CompanyLog being a part of a database inheritance, hence implements one of the supported strategies for that (currently TPH (Table-per-hierarchy) and starting from EF Core 5.0, TPT (Table-per-type)).

In fact the way it is shown in the post (i.e. without additional data annotations and/or fluent configuration) I'm getting a single table with disciminator column, which is the implementation of TPH. Probably you have something additional which gives you TPT - two tables, the "base" holding the base properties and "derived" holding just the additional properties.

What you need is either TPC (Table-per-class) or no database inheritance at all. The former is not supported yet, and the later can be achieved with the following fluent configuration (no data annotation exist so far):

modelBuilder.Entity().HasBaseType((Type)null);

Multi level Inheritence in EF Core from existing entity

1 Answers