Checking property of derived entity type using EF6?

Question

I have a IQueryable<BaseEntity> and there are derived entities EntityA and EntityB. I want my query to return ALL EntityA objects and only those EntityB objects which have a certain property not set to a certain value.

Unfortunately, the following code:

IQueryable<BaseEntity> baseEntities = GetBaseEntities();
var result = baseEntities.Where(x => !(x is EntityB) || ((EntityB) x).Prop != MyConstants.Value).ToList();

Throws an error:

NotSupportedException: Unable to cast the type 'BaseEntity' to type 'EntityB'. LINQ to Entities only supports casting EDM primitive or enumeration types.

How to overcome this problem?

https://stackoverflow.com/questions/18976495/linq-to-entities-only-supports-casting-edm-primitive-or-enumeration-types-with-i — Roman Ryzhiy, Sep 07 '20 at 13:20
I don't see where I could put the "where T : class" modifier, I don't have any generics in my code.. — D.R., Sep 07 '20 at 13:55

score 0 · Answer 1 · answered Sep 08 '20 at 07:01

0

One workaround seems to be the following:

GetAllEntityA().Cast<BaseEntity>().Concat(GetAllEntityB(b => b.Prop != MyConstants.Value))

I'm still looking for a better answer though.

answered Sep 08 '20 at 07:01

D.R.

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Checking property of derived entity type using EF6?

1 Answers1