Question

I would like to get a LINQ-to-SQL query that returns only one item, not a collection of them?

For example, I have a list of products with a particular name. There are no products with duplicate names in the database, so I want to be able to query and return just that instance of that product.

Products product = from p in _productContext.Products                     where p.name.Equals('BrownShoes')                     select p; 

How do I do something like that?

Answer 1

Use Single:

Product product = _productContext.Products                                  .Single(p => p.Name == 'BrownShoes'); 

or

Product product = _productContext.Products                                  .Where(p => p.Name == 'BrownShoes')                                  .Single(); 

There’s no query expression syntax for Single, so you have to call it as a normal extension method. At that point your query is simpler written entirely with dot notation, hence the form above. You could write it as:

Product product = (from p in _productContext.Products                     where p => p.Name == 'BrownShoes'                    select p).Single(); 

But that’s got a lot more fluff. If there isn’t exactly a single element in the result, an exception will be thrown.