Question

I need to set my connection string for Linq to Sql based on an environment variable. I have a function which will return the connection string from the web.config based on the environment variable, but how do I get Linq to always use this “dynamically created” connection string (preferably without having to specify it every time)?

I know I can specify the connection string using the constructor, but how does that work when using the datacontext in a LinqDataSource?

Answer 1

Use:

MyDataClassesDataContext db = new MyDataClassesDataContext(dynamicConnString);

For a LinqDataSource, intercept the ContextCreating event and create the DataContext manually as above:

protected void LinqDataSource_ContextCreating(object sender, LinqDataSourceContextEventArgs e)
{
    e.ObjectInstance = new MyDataClassesDataContext (dynamicConnString);
}

From MSDN:

By default, the LinqDataSource control
creates an instance of the type that
is specified in the ContextTypeName
property. The LinqDataSource control
calls the default constructor of the
data context object to create an
instance of the object. It is possible
that you have to use a non-default
constructor or you have to create an
object that differs from the one
specified in the ContextTypeName
property. In that case, you must
handle the ContextCreating event and
manually create the data context
object.