CODEWITHSUNDEEP
c#entity-frameworklinq
vaindil
vaindil

Reputation: 7864

Entity Framework - Filter LINQ by ICollection type using TPH

I'm have a class, Main, that has an ICollection of various types (SubA and SubB, parent class is Parent). I need to write a LINQ query that filters based on these subtypes in EF using table-per-hierarchy. TPH doesn't allow querying the Type column directly, so I'm trying to figure out a workaround. I have a method on Parent to get the type string. LINQ doesn't support this, however.

How can I perform a LINQ query from Main to filter on the type of each child (SubA and SubB), as well as one additional property of the child?

This is the class method to get the type:

public virtual string ReturnType()
{
    return GetType().BaseType.Name;
}

This is the LINQ query I was attempting, but fails because ReturnType() isn't supported in LINQ.

// Main query defined elsewhere in function
query = query.Where(main => main.children.All(child =>
                   (child.ReturnType() == "MS" || child.ReturnType() == "TL") &&
                   child.StatusId != 4);

Upvotes: 0

Views: 673

Answers (1)

Hopeless
Hopeless

Reputation: 4773

You can do something like this:

query = query.Where(m => m.StatusId != 4 && (m is SubA || m is SubB));

Or trickier with OfType:

var subQuery = query.Where(m => m.StatusId != 4);
query = subQuery.OfType<SubA>()
                .Cast<Main>()
                .Union(subQuery.OfType<SubB>().Cast<Main>());

Upvotes: 3

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