Entity Framework v1

In Entity Framework v1 you could create a “Function Import” from these stored procedures types, but there would be no generated code that would give you access to them directly in the ObjectContext object.  You could only access them via pure Entity SQL.

To add a “Function Import” you would just add the sproc to your entity model as your normally would, then right-click on the “Function Imports” in the “Model Browser”, and select “Add Function Import…”.  This would bring up the following screen which would allow you to add your function.

If you selected that the function returned an Entity, then you would be able to access that entity in the ObjectContext. However, if you selected scalar or void, then you would have to manually write some kind of Entity SQL.  It would be nice if these “Function Imports” appeared as operations in the ObjectContext as well.

Entity Framework 4.0 Solution

Microsoft finally completed the story for “Function Imports” in Entity Framework 4.0. As you can see in the image below, the “Add Function Import” dialog is virtually the same except for the new option to return a complex type.

You can select the None and Scalar return types as you could before.  However, when the “Function Import” is created, some new code is injected into the Model code behind file that materializes the stored procedure into an operation on the ObjectContext itself:

public ObjectResult<Nullable<global::System.Int32>> GetProductCountByCategoryId(

    Nullable<global::System.Int32> categoryID)

{

    ObjectParameter categoryIDParameter;

    if (categoryID.HasValue)

    {

        categoryIDParameter = new ObjectParameter("CategoryID", categoryID);

    }

    else

    {

        categoryIDParameter = new ObjectParameter(

            "CategoryID", 

            typeof(global::System.Int32));

    }

    return base.ExecuteFunction<Nullable<global::System.Int32>>(

        "GetProductCountByCategoryId", 

        categoryIDParameter);

}

A couple of nice things about this are:

1. No matter what we select as the return type, it wraps it as a Nullable type since a database value can always be null
2. The results are wrapped in an ObjectResult which makes it consistent with all other queries.

And as we expect, we can directly access these operations in our code:

using (var context = new NorthwindEntities())

{

    ObjectResult<int?> result =

        context.GetProductCountByCategoryId(1);

    MessageBox.Show(

        result.FirstOrDefault().Value.ToString());

}

New “Execute” operations

If you look at the last line of the code generated by “Add Function Import”, you might notice is making a call to a new method called ExecuteFunction<T>.  This method isn’t marked public, but there are two new methods on ObjectContext that we can use to execute functions:

1. int ExecuteStoreCommand

   This method seems to work like “ExecuteCommand” and returns in int representing the result

2. T ExecuteStoreQuery<T>
   
   This appears to be more of a combination of “ExecuteScalar”, “ExecuteNonQuery”, and “ExecuteReader”.

These methods give us the ability to run any imported stored procedure in a variety of ways.  Most users, will want to just stick with the generated operations, but its always good to have options!

The video is available through JupiterMedia and can be viewed at http://www.internet.com/video/. Just look for the "Developer Video" titled "Custom Sprocs in Entity Framework".

Direct links are:
http://www.internet.com/player/index.php?bcpid=1534611832&bclid=1433966034&bctid=22915014001

Customers c = new Customers();

When this database is generated using the PluralizationService, the names are set correctly.

Manually using the PluralizationService

The PluralizationService is in the System.Data.Entity.Design.dll under the System.Data.Entity.Design.PluralizationServices namespace.

It is an abstract class and hence, can’t be directly instantiated.  However, there is a static CreateService method on the class to access instances of the service for various cultures.  At this time, the only culture implemented is “en-us”.

It would have been very nice if this were implemented at a more core level of .Net since this could potentially be useful for a lot more than just for Entity Framework design.  Here are some examples using the service:

// Create an instance of the service for

// a particular culture (only 'en-us' atm)

PluralizationService ps =

    PluralizationService.CreateService(

         CultureInfo.GetCultureInfo("en-us"));

// Convert strings to plural or singular

string pluralName = ps.Pluralize("Goose");

string singularName = ps.Singularize("Territories");

// Note: Correctly returns Geese and Territory

// Check if strings are plural or singular

bool isPluralName = ps.IsPlural("Sheep");

bool isSingularName = ps.IsSingular("Sheep");

// Note: Correctly sees both of these as true

Adding your own pluralization mapping

There is an interface using by the PluralizationService called ICustomPluralizationMapping that isn’t publicly exposed.  However, since it is implemented, you can cast the service to this interface and make use of the AddWord method to add your own mapping.

In this example, we add a new word called “Foo” with the plural version being “Foos”:

// Create an instance of the service for

// a particular culture (only 'en-us' atm)

PluralizationService ps =

    PluralizationService.CreateService(

        CultureInfo.GetCultureInfo("en-us"));

// Cast to the mapping interface

ICustomPluralizationMapping mapping =

    ps as ICustomPluralizationMapping;

// Add a new word mapping

mapping.AddWord("Foo", "Foos");

EntityModelSchemaGenerator generator =

    new EntityModelSchemaGenerator(

        entityContainer,

        ps);

var edm = generator.GenerateMetadata(); 

The video is available through JupiterMedia and can be viewed at http://www.internet.com/video/. Just look for the “Developer Video” titled “ADO.Net Entity Framework”.

Direct links are:
http://www.internet.com/player/index.php?bcpid=1534611832&bclid=1433966034&bctid=4551661001
http://link.brightcove.com/services/link/bcpid1431564240/bclid1433966034/bctid4551661001