Beginning ASP.NET 4.5 in CSharp and VB Opsylum

512 x CHAPTER 14 LINQ AND THE ADO.NET ENTITY FRAMEWORK
anonymous type is a type whose name and members you don’t define up front as you do with other
types. Instead, you construct the anonymous type by selecting data and then letting the compiler
infer the type for you. The anonymous type can only be accessed within the method that declared it,
and as such you cannot return an anonymous type from a method.
If you don’t define the actual type and give it a name, how can you access the type and its properties?
This is once again done with type inference, where the compiler can see what data is assigned
to a variable and then creates a new, anonymous type on the fly.
Creating an anonymous type is easy; instead of selecting the actual object using something like
Select review, you use the new keyword in C# and New With in Visual Basic, and then define the
properties you want to select between a pair of curly braces:
VB.NET
Dim authorizedReviews = From myReview In myEntities.Reviews
Where myReview.Authorized = True
Select New With {myReview.Id, myReview.Title, myReview.Genre.Name}
C#
var authorizedReviews = from review in myEntities.Reviews
where review.Authorized == true
select new { review.Id, review.Title, review.Genre.Name };
Although the type is anonymous and cannot be accessed by name directly, the compiler is still able
to infer the type, giving you full IntelliSense for the new properties that were selected in the query.
Figure 14-5 shows how you access the properties of the anonymous type in the authorizedReviews
variable, using the var keyword in C#.
FIGURE 14-5
Note that the preceding query accessed the actual Genre property of the Review. Besides its
GenreId (defined as a column in the table Review in the database), the Review class also has a
strongly typed Genre property, giving you direct access to the genre’s properties, like the Name, as
the previous query demonstrates.
Besides directly selecting existing properties — as shown in the query that selected the Id and Title
of the Review and the Name of the Genre — you can also make up property values and give them