Using a EF Repository with custom connection objects?

问题:

I am stuck in EF 6 and the documentation is sparse - not getting that solved for a day now.

I try to use Code First on a database repository we have. Due to complex initialization I must use my own factory method to initialize the context subclass and I must put my own sql connection in, or make my own factory.

THe following class initialization:

we have:

public class Repository : DbContext {  static string _connectionString;      static Repository() {         Database.SetInitializer<Repository>(null);         var type = typeof(System.Data.Entity.SqlServer.SqlProviderServices);         _connectionString = ** method to get connection string**     }      public static Repository Create() {         SqlConnection connection = new SqlConnection(_connectionString);         connection.Open();         connection.BeginTransaction(IsolationLevel.ReadCommitted).Commit();         return new Repository(connection);     } 

Sadly running it blows with the following exception on the first attempt to select some entity:

Unable to determine the provider name for provider factory of type 'System.Data.SqlClient.SqlClientFactory'. Make sure that the ADO.NET provider is installed or registered in the application config.

I am totally out of my mind how to fix that.

My config file in the using web application reads:

  <entityFramework>     <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">       <parameters>         <parameter value="v11.0" />       </parameters>     </defaultConnectionFactory>     <providers>       <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer, Version=6.0.0.0" />     </providers>    </entityFramework> 

Anyone can tell me how to fix that? My alternative is to move back to model first - but I would really like to give code first a try here.

回答1:

I had the same requirements for my projects: EF repositories had to accept connection instances created from my own factory. To that end I chose to completely ignore the EF config file scheme. Instead, I did the following:

public class Repository : DbContext {     static Repository ()     {         Database.SetInitializer<Repository>(null);     }      public Repository(SqlConnection existingConnection, bool contextOwnsConnection)         : base(existingConnection, contextOwnsConnection)     {     }      protected override void OnModelCreating(DbModelBuilder modelBuilder)     {         // creating the model myself     }     // (...) } 

Since it can accept connection instances from the outside I'm free to use whatever connection factory I want and completely ignore EF's config file scheme.

If you want your connection factory inside the repository (which I don't recommend for the sake of separating concerns), you could add the following to the above:

public Repository()     : base(CreateConnection(), true) { }  private static SqlConnection CreateConnection() {     // do whatever you have to do to create your SqlConnection instance, using your own rules } 

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