Entity Framework Code First Find vs SingleOrDefault (Eager Loading)

Question

I'm using Entity Framework 4.2 (Code First) to access my database. I was under the assumption that if I queried an entity using `SingleOrDefault` it would only query the database if the entity was not already being tracked, but this does not appear to be the case. The `Find` method on the other hand, does appear to be doing this. The problem with `Find` is that it doesn't appear to allow me to load related data. Is there a way to use the `Find` method but also eagerly load data ? As an example, I want to load a book and all of its reviews: ``` // Load book from the database Book book = context.Books.Find(1); context.Entry(book).Collection.Load(); // Book.Reviews is now populated // Load book from the change tracker // This will include all Reviews as well Book book2 = context.Books.Find(1); ``` With `SingleOrDefault` I can load the Reviews when I get the book using Include: ``` // Load book + reviews from the database Book book = Book.Include("Reviews").SingleOrDefault(b…

Accepted Answer

The `Find` method is for searching single entity by key. The `SingleOrDefault` method is for executing query. Eager loading can be only part of the query which is really executed on the database so it cannot be used with `Find`.

As a workaround you can rewrite it this way:

```
// This will check only on in-memory collection of loaded entities
Book book = context.Books.Local.SingleOrDefault(b => b.Id == 1);
if (book == null)
{
    book = context.Books.Include(b => b.Review).SingleOrDefault(b => b.Id == 1);
}
```

Entity Framework Code First Find vs SingleOrDefault (Eager Loading)

Solution

Problem