Allow mapping different entity types in a hierarchy to different store constructs (table/view/procedure/etc.)

[cjalex1313]

TPT inheritance with views:

Pretty plain question, I didn't find documentation about this nor did what I tried work.

[ajcvickers]

@cjalex1313 Yes. What did you try and it what way did it fail?

[cjalex1313]

I just tried again in an example web api proj.

Database structure:
CREATE TABLE Animal (
ID UNIQUEIDENTIFIER PRIMARY KEY,
[Type] INT NOT NULL DEFAULT 0,
[DogName] NVARCHAR(MAX) NULL,
[CatName] NVARCHAR(MAX) NULL
)

CREATE VIEW Dog as
SELECT
ID,
DogName as Name
from dbo.Animal where [Type] = 1

CREATE VIEW Cat as
SELECT
ID,
CatName as Name
from dbo.Animal where [Type] = 2

---

DTO Classes

public class Animal
{
    public Guid ID { get; set; }
}

public class Dog : Animal
{
    public string Name { get; set; }
}

public class Cat : Animal
{
    public string Name { get; set; }
}

EF Context

public class AnimalContext : DbContext
{
    public DbSet<Animal> Animals { get; set; }
    public DbSet<Dog> Dogs { get; set; }
    public DbSet<Cat> Cats { get; set; }

    public AnimalContext(DbContextOptions<AnimalContext> options)
: base(options)
    { }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);
        modelBuilder.Entity<Animal>(e =>
        {
            e.ToTable("Animal");
            e.HasKey("ID");
        });
        modelBuilder.Entity<Dog>(e =>
        {
            e.ToView("Dog");
            e.Property(d => d.Name).HasColumnName("Name");
        });
        modelBuilder.Entity<Cat>(e =>
        {
            e.ToView("Cat");
            e.Property(d => d.Name).HasColumnName("Name");
        });
    }
}

By querying anything from the context I'm getting a error message of this type:

System.InvalidOperationException: Both 'Cat' and 'Animal' are mapped to the table 'Animal'. All the entity types in a hierarchy that don't have a discriminator must be mapped to different tables. See https://go.microsoft.com/fwlink/?linkid=2130430 for more information.

[smitpatel]

e.ToTable("Animal");

You are mapping Animal to table and derived types to view. Either map all of them to view or all of them to table.

[cjalex1313]

Ok.. well, that's not an option for me unfortunately

[cjalex1313]

In anycase thanks for the info. Much appreciated

[AndriySvyryd]

Ok.. well, that's not an option for me unfortunately

You can map all types using ToTable even if they are views in the database. The difference is mostly in how Migrations behave, which I assume you don't use.

Alternatively, calling ToTable(null) as well on derived types might make this work.