Question

I’m creating a multi-tenant Asp.Net MVC 3 Web app, and using EF4.1 code first for the db model.

For development I’m happy to use SqlServerCE in App_Data, and for production this will move to Sql Server 2008.

Say my context is called “MyModels”, by default code-first looks for a connection string called “MyModels” in Web.config. This can be told to use a file in App_Data or changed to access a database in SQL2008. All fine so far.

But because of multi-tenancy, I’d like the SqlServerCE filename to match the unique id of the tenant (so App_Data would have “client_x.sdf”, “client_y.sdf”; Sql Server 2008 would have separate databases). I can’t work out how to direct to these different databases.

I’ve tried MyModels inheriting from DbContext and supplying a connection string (using a ‘placeholder’ conn string in Web.config and replacing “{clientId}” with the unique id), and I’ve also tried setting the connection string in the MyModels constructor:

base.Database.Connection.ConnectionString = xxx;

but this never seems to work. I always get the following error:

A network-related or instance-specific error occurred while
establishing a connection to SQL
Server. The server was not found or
was not accessible. Verify that the
instance name is correct and that SQL
Server is configured to allow remote
connections. (provider: Named Pipes
Provider, error: 40 – Could not open a
connection to SQL Server)

(This suggests it’s not yet ‘configured’ to use SqlServerCE, and so is trying to connect to Sql Server. I think!)

Tracing the code, Database.Connection.ConnectionString hasn’t been read from Web.config at this point, so I can’t search and replace that, and, possibly, it’s getting overwritten by the ‘placeholder’ conn string later in the pipeline.

I reckon this must be quite straightforward and I just can’t find the ‘hook’. Can anyone please help?

Answer 1

I’ve figured it out, and it’s because I’m a bit dumb. Sorry! I was just trying to set the ConnectionString to be the connectionString from Web.config, but I actually need to build it using the DbConnectionStringBuilder. If I replace the ConnectionString property of the builder, then use the builder to set the EF conn string, it works.