Efcore: Fluent API property expressions does not support chained member access

[adamvoss]

With EF7 the mapping modelBuilder.Entity<Entity>().Property( x => x.Irrelevant.Property1 ), throws an exception:

System.ArgumentException: The expression 'x => x.Irrelevant.Property1 ' is not a valid property expression. The expression should represent a property access: 't => t.MyProperty'.

This is more limited than EF6. In EF6 it is valid to chain member access to map a property on a nested object. That is a mapping such as the following was valid:

``` c#
...
Property( x => x.Irrelevant.Property1 )

That would work so long as you set `Irrelevant` in the entity's getter:

``` c#
public IrrelevantType Irrelevant
{
    get
    {
        return _irr ?? ( _irr = new IrrelevantType () );
    }
    set
    {
        return irr = value;
    }

I am not able to determine if this is something that is not implemented yet, an intentional change, or a bug.

EF: 7.0.0-beta4-12175

[rowanmiller]

This is because we don't yet support nested objects (or "complex types" as we typically call them). Here is the work item tracking it https://github.com/aspnet/EntityFramework/issues/246.

[adamvoss]

Thank you! It is good to know the right way to refer to them :thumbsup:

[douglasoliveirabh]

@rowanmiller Is there a solution to implement complex type mapping already?

[divega]

@douglasoliveirabh we added support for owned types in 2.0, which provides a superset of the capabilities of complex types.

However owned types are never mapped by convention. I.e. in order for a type to become an owned type you have to explicitly address it with the OwnsOne method.

Given that I am not sure it would be viable to enable chained member access in the Property<T> method.

Reopening so that we can discuss it.

[ajcvickers]

Discussed in triage and agreed that we should not do this because the semantics would not be clear, specially if done before any OwnsXxx call has been made.