实体框架| 一个表中的多个对象

Question

I have a strange legacy Table in SQL Server and I wonder if I can use the following logic:

Table [PartiesTable]
 - Id
 - FirstName
 - LastName
 - Name
 - Type

And the following classes:

public abstract class Party {
   public Guid Id { get; set; }
}

public class Person : Party {
   public string FirstName { get; set; }
   public string LastName { get; set; }
}

public class Company : Party {
   public string Name { get; set; }
}

And this is an example of the records

╔════╦═════════════╦══════════╦═══════╦══════╗
║ id ║ FirstName   ║ LastName ║ Name  ║ Type ║
╠════╬═════════════╬══════════╬═══════╬══════╣
║ 1  ║ John        ║ Kenedy   ║ NULL  ║ P    ║
╠════╬═════════════╬══════════╬═══════╬══════╣
║ 2  ║ Meresa      ║ Oslo     ║ NULL  ║ P    ║
╠════╬═════════════╬══════════╬═══════╬══════╣
║ 3  ║ NULL        ║ NULL     ║ ACME  ║ C    ║
╚════╩═════════════╩══════════╩═══════╩══════╝

I tried to follow the docs here ( https://docs.microsoft.com/en-us/aspnet/mvc/overview/getting-started/getting-started-with-ef-using-mvc/implementing-inheritance-with-the-entity-framework-in-an-asp-net-mvc-application ) but they refer to an example where you have 3 tables, which I do not have

Answer 1

This is actually the default behavior in EF code first. Just simply define your classes, map all of them to the table named PartiesTable and set the discriminator column. The configuration should look something like this:

modelBuilder.Entity<Party>()
            .Map<Person>(m => { m.Requires("Type").HasValue("P"); m.ToTable("PartiesTable");})
            .Map<Company>(m => { m.Requires("Type").HasValue("C"); m.ToTable("PartiesTable"); })
            .ToTable("PartiesTable");