Working With Complex Type in Entity Framework

Introduction

 

Today, we'll discuss Complex Types in the Entity Framework. As you know, the application data is stored in a table of the database represented in a row-column structure. So, in various cases the row-column format can be directly mapped to the entities, at times you may need to reorganize them.

 

For an example, we have the Student table and in that the Contact and Email represent the contact information of the Student. The entity that represents this table might not be as "flat" as a table. As an example, you can also use a new property named ContactInfo that is of class type and has properties like Mobile and Email. You can do this with the Entity Framework.

 

Working with Complex Types in Entity Framework

 

So, let's now proceed and suppose we have a Student Entity Model as shown below:

 

 

The Student entity has different columns in the table and from them there are two columns representing the Contact Information named Contact and Email. We can access these properties with the following code:

CollegeEntities CollegeDb = new CollegeEntities();

var DbQuery = from S in CollegeDb.Students
              where S.StudentID == 1
              select S;

Student ObjStudent = DbQuery.SingleOrDefault();

Int64 Student_Contact = ObjStudent.Contact;
string Student_Email = ObjStudent.EmailID;

Now, suppose we wish to isolate the contact information into a different class. We can do it by the following techniques:

• Refactor the existing property into a new class
• Map an existing class with a property

The techniques defined above needs to have a class property of complex type or we can say a property that is of a class type. Let's see how this is to be done with the following sections.

 

Making a Property to Complex Type by Refactor

 

This is the simple way to do this. Use the following procedure.

 

Step 1: Select both properties and just right-click to move them to a New Complex Type.

 

 

Step 2: After refactoring, both are shifted to the new Complex type. Change the name to StudentContact.

 

 

Step 3: Change the name of the newly created property.

 

 

Step 4: Change the type of Complex property.

 

 

Step 5: Now you can access the new property in you code as shown below:

 

 

Mapping Existing Complex type with Property

 

We saw in the previous section that a new complex type was created as a result of the refactoring process. We can map an existing complex type with a property also. Use the following procedure.

 

Step 1: In the Model browser, right-click on Complex Types to add a new Complex Type.

 

 

Step 2: Enter the name as StudentContactInfo of that complex type and then right-click to add a new Scalar Property.

 

 

Step 3: Select the appropriate type for the scalar property as shown below:

 

 

So far the new complex type is not mapped with the Student. We'll now map it.

 

Step 4: Change the type of property to StudentContactInfo as shown below:

 

 

Step 5: Now, right-click on the Student model to open Table Mapping.

 

 

Step 6: Now change it to the new complex type as shown below:

 

 

Step 7: Now the newly mapped property will work like this:

 

 

That's it.

 

Summary

 

We created a Complex Type property using various techniques using Entity Framework. Happy coding and thanks for reading.