Question

Using Visual Studio 2012 which was recently installed but now I can’t connect to our SQL Server database.

These are the steps I’m following

1. create App1.config

2. type this in App1.config:

    <?xml version="1.0" encoding="utf-8" ?>
    <configuration>
      <connectionStrings>
        <add name ="xxx" connectionString="USER ID=xx;PASSWORD=xx;PERSIST SECURITY INFO=True;Data Source=xx;Initial Catalog=xx" />
      </connectionStrings>
    </configuration>
   

3. Add a reference to the project to System.Configuration

4. Create access to namespaces via:

    using System.Data.SqlClient;
    using System.Data;
    using System.Configuration;
   

5. implement the following:

   using System;
   using System.Collections.Generic;
   using System.Linq;
   using System.Text;
   using System.Threading.Tasks;
   using System.Data.SqlClient;
   using System.Data;
   using System.Configuration;
   
   namespace ConsoleApplication10 {
       class Program {
           static void Main(string[] args) {
   
               SqlConnection conn = null;
               conn = new SqlConnection(ConfigurationManager.ConnectionStrings["xxx"].ConnectionString);
   
           }
       }
   }
   

6. I’ve created a new console app and added the above and I still get an error NullReferenceException was unhandled Object reference not set to an instance of an object. …

EDIT

Via the immediate window I determined that the following is null:

ConfigurationManager.ConnectionStrings["xxx"].ConnectionString

If I hard-code the connection string into the constructor for SqlConnection then it connects ok

What am I missing – something really obvious!! Or is this in connection with my new VS ?

Answer 1

check what is in the ConfigurationManager.ConnectionStrings by excecuting at least the following:

if (ConfigurationManager.ConnectionStrings != null ) {
    Console.WriteLine(ConfigurationManager.ConnectionStrings.Count);
    Console.WriteLine(ConfigurationManager.ConnectionStrings[0].ConnectionString);
    Console.WriteLine(ConfigurationManager.ConnectionStrings[0].Name);
    ....
} else {
    Console.WriteLine("null");
}

This will highlight any obvious problems like duplication of the App.config file which could well be the case as you mentioned App1.config in the OP.