How can I make LINQ to SQL use a connection string which is being modified at runtime?

Question

I\'m experimenting some difficulties trying to use Connection String Builders (ADO.NET) within LINQ to SQL. Let me show you guys what I\'m trying to do:

Answer 1

It seems like you are trying to modify the connection string that is stored in the app.config file. When you use a no argument constructor for your data context, it reads what was configured at design time.

Try injecting your modified connection string into the constructor of the DataContext:

ConnectionStringSettings settings = ConfigurationManager.ConnectionStrings["LoremIpsum"];
SqlConnectionStringBuilder builder;
LINQTOSQLDataClassDataContext db;

if (null != settings) 
{   
    string connection = settings.ConnectionString;  
    builder = new SqlConnectionStringBuilder(connection);

   // passwordTextBox being the control where joe the user actually enters his credentials

    builder.Password =passwordTextBox.Text;  
    db = new LINQTOSQLDataClassDataContext(builder.ConnectionString);
 } }

Answer 2

You can force a DataContext to use a specific connection string with

DataContext db = new DataContext(myConnectionString);

The parameterless DataContext constructor will use a connection string from the App.config file first, then the connection string set at compile time.

Answer 3

You're forgetting to send in the connectionstring to the DataContext constructor.

Example:

LINQTOSQLDataClassDataContext db = new LINQTOSQLDataClassDataContext(builder.ConnectionString);