Functions - Entity Framework 6 Recipes - page 379

Solution
Suppose that we have an Employee entity containing the properties FirstName, LastName, and BirthDate, as shown
in Figure 11-3 .

Figure 11-3. An Employee entity with a few typical properties

We want to create a model-defined function that returns the full name of the employee by combining the
FirstName and LastName columns. We want to create another model-defined function that returns the age of the
employee based on the value in the BirthDate column.
To create and use these functions, do the following:

1.

Right-click the .edmx file in the Solution Explorer, and click Open With ➤ XML Editor. This
will open the .edmx file in the XML Editor.

2.

Insert the code in Listing 11-5 just below the <Schema> tag in the conceptual models
section of the .edmx file. This defines the functions in the model.

Listing 11-5. Code for Model-Defined Functions

<Function Name="FullName" ReturnType="Edm.String">
<Parameter Name="emp" Type="EFRecipesModel.Employee" />
<DefiningExpression>
Trim(emp.FirstName) + " " + Trim(emp.LastName)
</DefiningExpression>
</Function>
<Function Name="Age" ReturnType="Edm.Int32">
<Parameter Name="emp" Type="EFRecipesModel.Employee" />
<DefiningExpression>
Year(CurrentDateTime()) - Year(emp.BirthDate)
</DefiningExpression>
</Function>

3.

Insert into and query the model using code similar to the pattern shown in Listing 11-6.

Listing 11-6. Inserting into and Querying the Model Invoking the Model-Defined Functions
Using Both eSQL and LINQ
class Program
{
static void Main(string[] args)
{
RunExample();
}