Is there a way to change connection string in database first?

entity-framework database-first
James picture James · May 9, 2012 · Viewed 26k times · Source

I have several databases, the schema of them are same. When I use database-first, the connection string is specified when I create the edmx file. I want to know, is there a way to change the connection string? This is, so I can choose which database to operate.

Answer

rjchicago picture rjchicago · May 7, 2014

We do not store connection strings in our web.configs, so the accepted solution would not work for us. If you simply attempt to provide the connection string via the base DbContext constructor, you'll get the following exception:

Code generated using the T4 templates for Database First and Model First development may not work correctly if used in Code First mode. To continue using Database First or Model First ensure that the Entity Framework connection string is specified in the config file of executing application. To use these classes, that were generated from Database First or Model First, with Code First add any additional configuration using attributes or the DbModelBuilder API and then remove the code that throws this exception.

To resolve this, create a partial class of your context as follows and format your connection string with the additional EF metadata (where MyContext is your context model name (e.g. your model name is MyModel.edmx, than the MyContext in code below is replaced with MyModel with all three extensions .csdl, .ssdl, .msl used)):

public partial class MyContext
{
    public MyContext(string connStr)
        : base(string.Format(@"metadata=res://*/MyContext.csdl|res://*/MyContext.ssdl|res://*/MyContext.msl;provider=System.Data.SqlClient;provider connection string='{0}'", connStr))
    {
    }
}

Related questions

Adding a New Column to an Existing Table in Entity Framework

I have added a new column to a table in my database. The table is already defined in the existing Entity Framework model. I've been through most of the items here on how to do this and it still fails. …

Read More
Code First vs. Database First

I created an Entity Framework model based on an existing database, then generated the POCO entities from the model. The connection string in my web.config isn't Entity Framework, it's just the standard connection string (it's missing the CSDL, SSDL, …

Read More
Entity Framework cant use the DbContext, model being created

I am using EF 4.1, and I create a normal EF edmx file. I generate it from a DB. When it's been generated I rightclick and select add code generation item, to generate new classes, and use the DbContext instead. I …

Read More