What constitutes explicit creation of entities in LINQ to SQL? What elegant "solutions" are there to
- by Marcelo Zabani
Hi SO, I've been having problems with the rather famous "Explicit construction of entity type '##' in query is not allowed." error.
Now, for what I understand, this exists because if explicit construction of these objects were allowed, tracking changes to the database would be very complicated.
So I ask: What constitutes the explicit creation of these objects? In other terms:
Why can I do this:
Product foo = new Product();
foo.productName = "Something";
But can't do this:
var bar = (from item in myDataContext.Products
select new Product {
productName = item.productName
}).ToList();
I think that when running the LINQ query, some kind of association is made between the objects selected and the table rows retrieved (and this is why newing a Product in the first snippet of code is no problem at all, because no associations were made). I, however, would like to understand this a little more in depth (and this is my first question to you, that is: what is the difference from one snippet of code to another).
Now, I've heard of a few ways to attack this problem:
1) The creation of a class that inherits the linq class (or one that has the same properties)
2) Selecting anonymous objects
And this leads me to my second question:
If you chose one of the the two approaches above, which one did you choose and why? What other problems did your approach introduce? Are there any other approaches?
