why my DataClassesDataContext has no default constructor?

I have a connection string defined in my web.config like:

<connectionStrings>
<add name="LibraryConnectionString"  connectionString="Server=.\SQLEXPRESS3;Database=Library;Integrated Security=true" />

Well...lI do not understand why when i drag-and-drop tables into a new DataClasses dbml it does not construct a default constructor specifying the connection string....

I only have constructor with params like:

public DataClassesDataContext(string connection) : 
        base(connection, mappingSource)
{
   开发者_如何学JAVA OnCreated();
}

I do need a default constructor for LinqDataSource..

Can anyone suggest a work-around?

Thanks

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• Step 1 : Remember your dbml file name and delete your dbml file.
• Step 2 : Then add a new dbml file with the same previous name to the same location (add -> add new Item -> LINQ to SQL Classes).
• Step 3 : Double click on the dbml file in the Solution Explorer.
• Step 4 : Now Drag and drop all the tables to that layout of dbml.
• Step 5 : Finally add all the associations with the tables as previously you have done.
• NO ERRORS,,,No need to make a default constructor by your own.It automatically create the constructor with out arguments if you do as i mentioned,,,and when ever you change any data it can automatically change as you need ...THANX ..PLEASE VOTE MY ANSWER

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You can make a default constructor in a separate file like this:

partial class DataClassesDataContext
    public DataClassesDataContext()
         : this(ConfigurationManager.ConnectionStrings["LibraryConnectionString"].ConnectionString) {
    }
}

Make sure not to call OnCreated twice.