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Using MySQL with Entity Framework and ASP.NET MVC – Part I

April 1st, 2009

I would like to take a look at creating an object model for a MySQL database schema in .NET and accessing that data with LINQ queries.

After some research on the subject I figured the path of least resistance would be to try out Microsoft’s latest data access technology, Entity Framework. Now, I know people are not thrilled with some of the apparent short comings of EF – friend’s don’t let friend’s use EF, but still we march on.

Prerequisites

Also, I am using ASP.NET MVC as our test harness so you will also need the ASP.NET MVC Framework installed along side Visual Studio. You can download that here. If you are unfamiliar with ASP.NET MVC, I suggest you get with the program.

Getting Started

I am going to assume that you are able to get the MySQL database engine along with the GUI tools installed. If not, read more here.

Once you have your MySQL database up and running open the MySQL Administrator. Fill in your connection information and credentials and select Ok.

Next, we are going to select the Catalogs icon and create a new schema (or database for SQL Server people). Right-click in the Schemata list and select Create New Schema.

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Enter your new schema name and select Ok.

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Open the MySQL Query Browser from the Tools menu. Open and New Script Tab from the File menu and run the following scripts. This will create two tables. (note: we’re using the default MyISAM database engine)

CREATE TABLE  `demotest`.`category` (

  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,

  `name` varchar(45) NOT NULL,

  PRIMARY KEY (`id`)

) ENGINE=MyISAM AUTO_INCREMENT=2 DEFAULT CHARSET=latin1;

DROP TABLE IF EXISTS `demotest`.`product`;

CREATE TABLE  `demotest`.`product` (

  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,

  `name` varchar(45) NOT NULL,

  `categoryid` varchar(45) NOT NULL,

  PRIMARY KEY (`id`)

) ENGINE=MyISAM AUTO_INCREMENT=2 DEFAULT CHARSET=latin1;

Now, in Visual Studio create a new ASP.NET MVC Web Application. Select, Yes to create a Unit Test project along side the web application. We may use this later.

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Next, in your Visual Studio Server Explorer create a new data connection. Change your data source to MySQL and enter your database information.

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Notice you can now access your MySQL database from the Server explorer.

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The next step is to add the Entity Framework model to our project. Right-Click on the Model folder that is created by the ASP.NET MVC project template and select Add New Item. Locate the ADO.NET Entity Data Model option and press Ok.

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Select the Generate from database option and click Next. Select, Yes to putting your connection string information in your web.config. This might not be the best option for your “real world” apps but it is just fine for us. Now select the option to generate objects for our tables and input your Model’s namespace.

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Select Finish and the EF magic happens.

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Now that our EF model has been generated we are going to wrap that in a simple repository pattern. Here is what the repository type will look like for Products.

public class ProductRepository
{

    MySqlEntities mySqlEntities = new MySqlEntities();

    public IQueryable<Product> Select()

    {

        var result = from p in mySqlEntities.ProductSet

                     select p;

        return result;

    }

    public IQueryable<Product> Select(int id)

    {

        var result = from p in Select()

                     where p.id == id

                     select p;

        return result;

    }

    public void Add(Product product)

    {

        mySqlEntities.AddToProductSet(product);

    }

    public void Delete(Product product)

    {

        mySqlEntities.DeleteObject(product);

    }

    public void Save()

    {

        mySqlEntities.SaveChanges();

    }
}

We will do the same for Categories…

public class CategoryRepository
{

    MySqlEntities mySqlEntities = new MySqlEntities();

    public IQueryable<Category> Select()

    {

        var result = from p in mySqlEntities.CategorySet1

                     select p;

        return result;

    }

    public IQueryable<Category> Select(int id)

    {

        var result = from p in Select()

                     where p.id == id

                     select p;

        return result;

    }

    public void Add(Category category)

    {

        mySqlEntities.AddToCategorySet1(category);

    }

    public void Delete(Category category)

    {

        mySqlEntities.DeleteObject(category);

    }

    public void Save()

    {

        mySqlEntities.SaveChanges();

    }

}


So far…

We have created our database schema in MySQL using the MySQL GUI Tools. In Visual Studio, we added a connection to our database in the Server Explorer. We generated a Entity Framework object model for or database schema, and wrapped that model with repositories.

Next time we will use those repositories to access and modify our data from ASP.NET MVC controllers. Also, we will add views to round out our demo with a simple user interface for Add, Edit, and Create scenarios.

Source

Download File – Source
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