How to set connection string in Linq to SQL constructor

Question

Im trying to set a connection string for a my data access layer which is using a value from my Web.Config file from another project.

I create a new class library and add a dbml (Linq to SQL) file and drag a table.

I then add this code to the code file

Partial Public Class MyDataContext
    Public Sub New()
        MyBase.New(ConfigurationManager.ConnectionStrings("WebConnectionString").ConnectionString, mappingSource)
        OnCreated()
    End Sub
End Class

This gave me an error "'Public Sub New()' has multiple definitions with identical signatures."

I understood what the error means so did a quick search on a way around it as when i recompiled the project the same problem remained. The way to approach this was/is to override the OnCreated method so i changed the code to:

Private Sub OnCreated()
   Me.New(ConfigurationManager.ConnectionStrings("WebConnectionString").ConnectionString, mappingSource)
End Sub

This gave the error "Constructor call is valid only as the first statement in an instance constructor" but not a lot of ways to overcome it (well i see a few C# examples but im sure im an converting it to the correct VB .Net code)

After further research no matter what i do, i dont seem to be able to set the connection string in my DAL which should be using the Web.Config connection string value from another project.

What could i be doing wrong?

James Curran · Accepted Answer · 2014-09-02 19:03:44Z

3

OK, In C# first:

 partial class MyDataContext
 {
     public static MyDataContext Create()
     {
          return new MyDataContext(ConfigurationManager.ConnectionStrings("WebConnectionString").ConnectionString, 
           mappingSource);
     }
 // etc
 }

Now, my attempt to translate that in VisualBasic.NET

 Partial Public Class MyDataContext
 Public Shared Function Create() as MyDataContext
    return New MyDataContext (ConfigurationManager.ConnectionStrings("WebConnectionString").ConnectionString, 
           mappingSource)
End Function
End Class

Called via:

   Dim db as MyDataContext = MyDataContext.Create()

edited Sep 2, 2014 at 19:03

answered Sep 2, 2014 at 18:03

James Curran

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2 Comments

Computer Over a year ago

I get the error "Constructor call is valid only as the first statement in an instance constructor.". In case im doing something wrong then i right click the dbml file and select View Code. Thats where the above code is placed.

James Curran Over a year ago

Sorry, my vb is a bit shaky. I fixed the syntax. Try it now.

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