Error with App.config connectionstrign in class library

Question

I have an error with connection string in class library project. In Appconfig I have this code:

  <connectionStrings>
    <add name="DefaultConnection" connectionString="Data Source=DESKTOP-123\SQLEXPRESS;Initial Catalog=MyDb;User ID=sa;Password=mypassword"  providerName="System.Data.SqlClient"/>
  </connectionStrings>

Connection string I call form a static function:

public static string ConnDb {
        get {
            return ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString;
        }
    }

When I use this connection string in function

Sqlconnection conn = new Sqlconnection(Class1.ConnDb)

I have some error like

{"Object reference not set to an instance of an object."}

What can I do?

Answer 1

您可以使用appSettings作为替代选项。