What prevents Entity Framework from creating classes when projecting using Select?

Asked Apr 29 '17 at 21:08

Active Apr 29 '17 at 21:08

Viewed 25 times

Usually when I query with Entity Framework I do something like the following:

using (var db = MyDataContext()){
    db.MyTable.Select(d => new DataModel(){
        Id = d.Id,
        Name = d.Name
    });
}

But sometimes I get an error at runtime "the entity or complex type 'DataModel' cannot be constructed in a linq to entities query". How can I know if a type can be constructed without running the program and testing?

asked Apr 29 '17 at 21:08

Jamie Twells

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Does it throw the same error in the above code? As long as you are projecting into a dto class, I don't think you should any problems. – Amanvir Mundra Apr 30 '17 at 11:30
But what makes something a DTO class is my question. When is a DTO not a DTO according to Entity Framework? – Jamie Twells Apr 30 '17 at 11:31
You cannot project to a partial model/table class. Rest all should be ok. – Amanvir Mundra Apr 30 '17 at 11:33
http://stackoverflow.com/questions/5325797/the-entity-cannot-be-constructed-in-a-linq-to-entities-query – Amanvir Mundra Apr 30 '17 at 11:35
Ah ok, so as long as the class isn't already mapped to a table, I can project into it safely? Add an answer and I'll accept it. – Jamie Twells Apr 30 '17 at 11:43

What prevents Entity Framework from creating classes when projecting using Select?

0 Answers0