Question

I have a WPF application in which I’m trying to use Entity Framework 4.1 Code First for Data Access Logic. I’m using MySQL as DBMS. For simplicity I have created just one data class User:

public class User
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }

    [Required]
    [MaxLength(50)]
    public string Name { get; set; }

    [Required]
    [MaxLength(50)]
    public string Surname { get; set; }

    [Required]
    [MaxLength(50)]
    public string Username { get; set; }

    [Required]
    [MaxLength(255)]
    public string Password { get; set; }
}

And I have an ApplicationContext class extending the DbContext like:

public class ApplicationContext : DbContext
{
    public ApplicationContext()
        : base()
    {
    }

    public DbSet<User> Users;
}

I add a connection string with the name ApplicationContext to the app.config file.

<configuration>
    <connectionStrings>
        <clear/>
        <add name="ApplicationContext" 
 connectionString="server=localhost;User Id=myuser;Password=mypassword;Persist Security Info=True;database=mydatabase" 
 providerName="MySql.Data.MySqlClient"/>
    </connectionStrings>
    <system.data>
        <DbProviderFactories>
            <remove invariant="MySql.Data.MySqlClient" />
            <add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient"
 description=".Net Framework Data Provider for MySQL" 
 type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data, Version=6.4.3.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" />
        </DbProviderFactories>
    </system.data>
</configuration>

And when I try to initialize the database with the following code inside the App.xaml.cs file OnStartup method, I get ProviderIncompatibleException saying The provider did not return a ProviderManifestToken string. And the inner exception says Unknown database.

Database.SetInitializer<ApplicationContext>(
    new DropCreateDatabaseIfModelChanges<ApplicationContext>());

this.AppDatabaseContext = new ApplicationContext();
this.AppDatabaseContext.Database.Initialize(true);

I think it tries to connect to the database with the database name I have provided in the connection string and fails since it does not exist. However, I expect that it should create one if there isn’t already.

I also tried to create the database by hand from MySQL and re-run the application, this time I get a different type of exception: NotSupportedException saying Model compatibility cannot be checked because the database does not contain model metadata. Ensure that IncludeMetadataConvention has been added to the DbModelBuilder conventions

I have searched the internet and tried many things to overcome this problem but couldn’t find a solution.

Any help will be greatly appreciated.

Answer 1

It could be a problem with the version of the ado.net provider for MySQL that you are using.

The latest version of dotconnect for MySQL supports code-first for EF 4.1, see http://www.devart.com/news/2011/dotconnects630.html