Question

Can I just point the connection string in Dbml.designer.cs to the connectionstring in the app.conf? I wrote the code below which it successfully point to the app.config.

public leDataContext() : 
    base(ConfigurationManager.ConnectionStrings["leConnString"].ToString(), mappingSource)
    {
        OnCreated();
    }

However whenever i modify or add a table into the dbml, it will start to auto replace that code into this

 public leDataContext() : 
            base("Data Source=.\\SQLEXPRESS;AttachDbFilename=\"D:\\My Projects\\App_Data\\le.mdf\";Integrated Security=True;Connect Timeout=30;User Instance=True", mappingSource)
    {
        OnCreated();
    }

I have expanded the “Connection” option. Set “Application Settings” to False

Answer 1

Don’t modify Dbml.designer.cs file manually, because it will be rewritten when you edit/add a table etc. as you said. Instead of this set the Connection property for the .dbml designer file to None and add a partial class with parameterless constructor:

public partial class leDataContext
{ 
   public leDataContext() : 
       base(ConfigurationManager.ConnectionStrings["leConnString"].ToString())
    {
        OnCreated();
    }    
}