If you know of any more good articles you have found yourself, let me know!

Enjoy!

The ADO.Net Entity Framework (2010) (MSDN) – If you don’t know or are unsure of what the Entity Framework is, then this might be a good place to start.  It provides a good overview with links to more articles going into details in specific areas.

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What’s New In Entity Framework 4 (Slides) – For those of you who are familiar with the first version of the Entity Framework in .Net 3.5 SP1, but have not yet delved into the next release, these slides give an overview of what has changed and what has been introduced.

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TUTORIAL: Model First using Entity Framework 4 and Visual Studio 2010 – This is a tutorial I wrote a while back for those with the Visual Studio 2010 beta who wanted to see the new model first functionality introduced in EF v2.

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Entity Framework v2 and Data Access Architecture Best Practices – Some design patterns and development style discussion for when using the EF v2 and Visual Studio 2010.

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N-Tier Application Patterns with Entity Framework v2 – A good article regarding designing N-Tier applications with EF v2, using .Net Framework 4, Visual Studio 2010 and WCF.

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Multiple Database Support in Entity Framework 4 – Interesting article discussing the database independence being introduced with the Entity Framework.

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BOOK: Professional ADO.Net 3.5 With LINQ and the Entity Framework - I am currently reading this book which tackles ADO.Net 3.5 with the Entity Framework.  Whilst this is not specifically for version 2, this seems to be a good into the the EF and worth a look if you are new to the subject.

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Technorati Tags: .NET 4.0, ef 4, ef v2, Entity Framework

In this post I am going to look at one of the most anticipated features, Model First.  In the first version of the Entity Framework, you took a pre-existing database and the tools would generate your entity model for you.  In v2.0, you now have the option of creating your entity model first and then generating your database DDL from your finished model.

To follow this tutorial you will need Visual Studio 2010 Beta 1, .Net Framework 4.0 Beta 1 installed, SQL 2005 or 2008 / SQL Express.

Please bear with me and let me know if there are any parts of this tutorial that are not completely clear.  I am new to writing these! So any comments welcome….

Creating your project and adding your blank entity model

Open Visual Studio 2010 and create a new Dynamic Data Entities Web Application project(you could another project type to host your entity model, such as an ASP.Net Web Application).

Once your project has been created add a new ADO.Net Entity Data Model to the project. 

You will then be asked about what the model should contain.  As with version 1 of the Entity Framework, you have two options, Generate from Database and Empty Model.  To a large extent, the latter was redundant in the first version of the framework, but with version 2 it becomes very useful.  Select Empty Model and click Finish.

Adding an entity and scalar properties to your model

You will now be presented with your empty model designer ready for you to add your entities.  Right click on the designer and select Add –> Entity…  For this example we will name our entity “Customer” and the entity set “Customers”.  This will create your Customer entity in the designer.

You will now need to add some properties to the entity.  You can do this by right clicking the entity and Add –> Scalar Property and then selecting the data type of the property. Do this and create two string scalar properties for Name and Email.

Adding complex types

You should now have a Customer entity with properties for the customer’s name and email address. A complex type is essentially a property that can contain sub properties.  To display this we are going to create one for the customer’s mailing address.

In your model browser, right click on the “Complex Types” folder and select Create Complex Type.  Rename this created type “Address”.  Now right click on the Address object you have created and select Add –> Scalar Property –> String.  Rename the created property “Line 1”.  Repeat this, adding properties for Line 2, Town, County, Post Code (you could use City, State, Zip if you are in the U.S. for example).

Once you have created your complex type, you can add this to your Customer entity by right clicking the entity and selecting Add –> Complex Property. If you name your property Address, then the property type should automatically be set to Address, which is what we have just created.  You can check this and alter the type via the properties of the complex property (that’s a lot of properties )

Create some additional entities

Once I had created my Customer entity, I then went through the same steps to create two additional entities for Order and Product. If you do this, then you should end up with something like below.

Adding entity associations

Now that we have our entities for Customer, Order and Product, we need to tell the model how the entities are associated.  For example, a customer will have related orders and an order will have related products.

To add our first association, right click the Customer entity and select Add –> Association. You will then be presented with the dialog shown below to actually define the association.  As you can see, the primary entity for this association is Customer which is related to Order with a multiplicity of one-to-many.  Here is where we also set the navigation properties which will allow us to access related entities.  So for example, the Customer entity will have a navigation property of “Orders”.  There is also a plain English description of the association you are about to create to ensure that you are creating it correctly.

Once you are happy click ok and the association will be shown on your model connecting the Customer and Order entities.

We now need to also create an association between the Order and Product entities using the same steps as above, but this time the properties of the association are slightly different as the multiplicity is many-to-many as show below.

Generating the database

Ok, so we have our model containing our entities.  Our entities have their properties and their associations, but we still do not have a database for our model to map to.  This is the bit I really like.  Right click on the model designer area and click “Generate Database Script From Model…”.

This will then open the standard database connection dialog we are all used to in Visual Studio. Add a connection, select your server and enter a name for your database (use a name that does not already exist, I called mine “ModelFirstTestDb”…..original I know!), then click OK.  You should then be prompted to create the database as seen below, so click Yes to create the database.

You should now see your new connection selected and the option to store the credentials in the web.config should be checked. Click next and the database schema scripts (DDL) will be generated for you and you will be presented with the generated script as below.  Take a minute to have a look through the DDL and see how it has created the tables and fields.  In the image below you can see the fields that have been generated to map to the complex type for the Customer address we created earlier.

Now we just need to click Finish and we will be warned that our existing mappings and store schema will be overwritten, click Yes to continue.

Execute your DDL

Now you need to take the generated script and execute it against your database.  The database itself will have been created, but in this beta version you still need to execute the scripts manually.  The ADO.Net team have indicated that this will not be the case in the final version.

Running your Dynamic Data Entities application

If you now open the Global.asax.cs file in your project and add the following line in the RegisterRoutes method, you should be able to run your application and see your new model and database in action;

DefaultModel.RegisterContext(typeof(Model1Container),new ContextConfiguration() { ScaffoldAllTables = true });

Technorati Tags: .net 4, ado.net, Entity Framework, tutorial, visual studio 2010

Model First

This is something that I am really excited about and something that has long been needed IMHO.

In .Net 3.5 you could take a database and generate your entity framework model from it.  In .Net 4.0 , however, it is possible to create your model first and then generate DDL for creating your database from your model. 

This is all fantastic and I can see me using this method alot, but whats even better is the fact that you will also have the ability to customise the DDL generation step yourself to suit your own needs.  For example, the default generation would be to generate a table per entity type, but you may have several entity classes that inherit from a parent class and in this instance you may want to modify the generator to produce a table per hierarchy structure for your database.

Deferred Loading

One of the things that people wish was available in the Entity Framework is deferred loading as it is in Linq to SQL. Well, now thanks to the ADO.Net team listening to the feedback, it is.  Previously, if you had a Customer object that contained Orders for each customer, you needed to explicitly call a Load method on the Customer object to be able to use the Order objects associated with it.

Now though, the following is possible;

using (NorthwindEntities db = new NorthwindEntities())
{
    db.ContextOptions.DeferredLoadingEnabled = true;

    foreach (Customer c in db.Customers)
    {
        if (c.Orders.Count > 10)
        {
            SendLoyaltyRewardToCustomer(c);
        }
    }
}

In the simple example above, you will notice that you do not need to explicitly load any Orders, but simply set the DeferredLoadingEnabled flag to true (this is off by default, but apparently there are ways to change this).

General Entity Framework Improvements

The following is a list from a recent post on the ADO.Net Team Blog of other key improvements coming to the Framework in this version;

1. 1. Development Approaches
      1. Model First development –  We’ve added functionality to the ADO.NET Entity Data Model designer to start from a Model and then have T-SQL and customized code generated.
      2. Testing applications that use the Entity Framework – Along with the patterns above we’ve added an interface, along with guidance, that enables better testability of applications that use the Entity Framework.

      Architectural Concerns

      1. Persistence Ignorance – Enabling developers to use their own classes without needing to introduce interfaces or other elements specific to the Entity Framework.
      2. Applications Patterns – Discussing patterns like the Repository and UnitOfWork patterns with guidance on how to use them with the Entity Framework
      3. Building N-Tier applications with the Entity Framework – Adding API’s and templates that make building N-Tier applications with the Entity Framework much easier.

      Entity Framework Improvements

      1. Customization of Code Generation – Integration with the ADO.NET Entity Framework Designer and T4 Templates in Visual Studio to provide developer controlled code generation.
      2. Small things that make development of applications simpler – Adding things like Pluralization and Singularlization in the model, lazy loading, and more stored procedure mapping make building applications that use the Entity Framework much easier.
      3. Customizing Queries – Adding support for existing LINQ operators, recognizing a larger set of patterns with LINQ, writing model defined functions along with the ability to use these in LINQ, and a number of other ways to create and customize queries.
      4. SQL Generation Readability Improvements – Improving the readability, along with TSQL performance optimizations, of the generated queries to make it much easier to understand what is happening
      5. And much, much more

Useful Links

The ADO.Net team have said that they have many mroe detailed posts on the way in the next couple of weeks so it’s well worth keeping an eye on their blog.  Plus, we should soon see a beta of Visual Studio 2010 and .Net 4.0 which should contain some of the aforementioned features.  I will be posting here when that’s released so keep an eye out for that.

ADO.Net Team Blog Post regarding Deferred Loading

ADO.Net Team Blog Post reagrding Model First in EF

ADO.Net Team Blog

Technorati Tags: .NET 4.0, ado.net, eneity framework