App.config不起作用？

Question

i have my App.Config Like this :

<?xml version="1.0" encoding="utf-8" ?>
<configuration>

 <connectionStrings>
    <add 
      name="MyProject.Properties.Settings.Default.dataConnection"
      connectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=address;
              Integrated Security=True;Connect Timeout=30;User Instance=True"
      providerName="System.Data.SqlClient" />
  </connectionStrings>
</configuration>

and when i want to use following code to get connection string , "Error 1 'Weather.Properties.Settings' does not contain a definition for 'dataConnection' and no extension method 'dataConnection' accepting a first argument of type 'Weather.Properties.Settings' could be found (are you missing a using directive or an assembly reference?) " error rises ,

string connectionString = 
   global::MyProject.Properties.Settings.Default.dataConnection;

Answer 1

To retrieve a connection string from the config file you could use the ConnectionStrings property:

string connectionString = ConfigurationManager
    .ConnectionStrings["MyProject.Properties.Settings.Default.dataConnection"]
    .ConnectionString;

Answer 2

I notice that the error message has this namespace:

"Weather.Properties.Settings"

While you are referencing

"MyProject.Properties.Settings"

Check that your namespaces are the same.