Configure multiple database Entity Framework 6

Question

In my solution I have 2 projects that use Entity Framework 6. Each points to a different database, both using the same data provide - SQL Server. A third project in my solution needs to use both databases. My problem is how to configure those context. I tried to create a configuration class in a separate assembly:

namespace OSAD_Base
{
    class EfDbConfiguration : DbConfiguration
    {
        public EfDbConfiguration()
        {
            SetProviderServices(SqlProviderServices.ProviderInvariantName, SqlProviderServices.Instance);
        }
    }
}

and referencing to this configuration in each context class:

namespace IntegrationDb
{
    [DbConfigurationType("OSAD_Base.EfDbConfiguration, OSAD_Base")]
    public partial class IntegrationEntities : DbContext
    {
        public IntegrationEntities(string connectionString)
            : base(connectionString)
        {
        }
    }
}

When initializing my first, all works correct, but when the second context initializes (Order does not matter) I get and error:

An instance of 'EfDbConfiguration' was set but this type was not discovered in the same assembly as the 'B1Entities' context. Either put the DbConfiguration type in the same assembly as the DbContext type, use DbConfigurationTypeAttribute on the DbContext type to specify the DbConfiguration type, or set the DbConfiguration type in the config file. See http://go.microsoft.com/fwlink/?LinkId=260883 for more information.*

I also tried to create an entityframework section in my app.config (of the start up project) but got the following error:

Configuration system failed to initialize

Unrecognized configuration section entityFramework

How can I use 2 separate EF Projects in the same solution?

Answer 1

It's not important that how many DbContexts you have(In entity framework 6). Just put connection strings in appConfig or webConfig of startup project.

Then you're ready to go.

Example of appConfig with two connectionString with Ef 6.01 & Sql Compact 4.0

<configSections>
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
  </configSections>
  <connectionStrings>
    <add name="MainDb" connectionString="Data Source=|DataDirectory|\Db.sdf" providerName="System.Data.SqlServerCe.4.0" />
    <add name="AnotherDb" connectionString="Data Source=|DataDirectory|\AnotherDb.sdf" providerName="System.Data.SqlServerCe.4.0" />
  </connectionStrings>
  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlCeConnectionFactory, EntityFramework">
      <parameters>
        <parameter value="System.Data.SqlServerCe.4.0" />
      </parameters>
    </defaultConnectionFactory>
    <providers>
      <provider invariantName="System.Data.SqlServerCe.4.0" type="System.Data.Entity.SqlServerCompact.SqlCeProviderServices, EntityFramework.SqlServerCompact" />
    </providers>
  </entityFramework>

And example of DbContexts:

public class AppDb : DbContext
{
    public AppDb()
        : base("MainDb")
    {

    }
}

public class AnotherDb : DbContext
{
    public AnotherDb()
        : base("AnotherDb")
    {

    }
}

It's not important that your contexts are in separated projects or not, only Config of startup project is important.

Let me know if any other information you need.

Good luck

Answer 2

Connection string of EntityFramework 6 should be inside configuration file that located (alert!) in execution folder. For example OP have multiple projects in solution, so the connection string must be in configuration file belongs to main executive project.

Now, if you want to define connection string in your code, you can make fake connection string in configuration file and give your entity's instance new connection string:

DBEntities e = new DBEntities();
e.Database.Connection.ConnectionString = "Data Source=MyServ;Initial Catalog=MyDB;Persist Security Info=True;User ID=sa;Password=***;Application Name=MyApp";

Answer 3

Here is what I did for two DB with EF6

Web.config

      <connectionStrings>
        <add name="EntityContainer" connectionString="metadata=res://WebService/Database.Database.csdl|res://WebService/Database.Database.ssdl|res://WebService/Database.Database.msl; .../>
        <add name="ArchiveEntityContainer" connectionString="metadata=res://WebService/Database.Database.csdl|res://WebService/Database.Database.ssdl|res://WebService/Database.Database.msl; .../>
      </connectionStrings>

Add second constructor in Database.Context.tt (be careful: auto-generated code)

public <#=code.Escape(container)#>(string connectionString)
    : base(connectionString)
{
}

Use

using (EntityContainer context = new EntityContainer())
{
    //...
}

using (EntityContainer context = new EntityContainer("ArchiveEntityContainer"))
{
    //...
}