Entity Framework - not using linked table id in insert query

Question

I have 2 tables, Foo and Bar, Foo has a link to a Bar record

public class Foo
{
    public int Id { get; set; }
    public Bar SomeBar{ get; set; }
}

public class Bar
{
    public int? Id { get; set; }
    ...
}

the SQL table ( with the FK constraint between the two tables ):

CREATE TABLE [dbo].[Foo] ( 
    [Id] INT IDENTITY (1, 1)  NOT NULL PRIMARY KEY,
    [SomeBarId] INT         NOT NULL,
    CONSTRAINT [FK_Foo_Bar] FOREIGN KEY ([SomeBarId]) REFERENCES [Bar]([Id]),
);

when I save the table, Entity does not use SomeBarId in the query , producing an error, while I have set a FK constraint between the two tables

Cannot insert the value NULL into column 'SomeBarId ', table 'dbo.foo'; column does not allow nulls. INSERT fails.

how do I tell entity to use the field SomeBarId when doing the insert ?

var someBar = await _context.Bars.FindAsync(1); // fetch a Bar record

foo.SomeBar = someBar; // linking the objects

_context.Foo.Add(foo);

await _context.SaveChangesAsync(); 

I expect EF to get someBar.Id and use it in the query when inserting Foo in DB

thanks for the time you'll spend helping me on this

Answer 1

Try adding ForeignKey attribute in class Foo and remove the nullable Id in Bar

public class Foo
{
    [ForeignKey("Bar")]
    public int Id { get; set; }
    public Bar SomeBar{ get; set; }
}

public class Bar
{
    public int Id { get; set; }
    ...
}