How to read connection string from App.config file using C #

Question

I use this code to read the connection string from my app.config file, but always returns a null value. My App.config file is in my project. Both methods result in null values:

public SqlConnection getConnection()
{
    try
    {
        // connectionString = ConfigurationManager.AppSettings["dbConn"];

        connectionString = ConfigurationManager.ConnectionStrings["dbConn"].ConnectionString;
        connectionString = System.Configuration.ConfigurationManager.AppSettings["dbConn"];
        sqlConnection = new SqlConnection(connectionString);  

        sqlConnection = new SqlConnection(connectionString);
    }
    catch (Exception ex)
    {

    }
    return sqlConnection;
}

This is my app.config file declaration:

<?xml version="1.0" encoding="utf-8" ?>
 <configuration>
  <connectionStrings>
    <add name="dbConn" providerName="System.Data.SqlClient"
          connectionString="Data Source=VANYA\SQLEXPRESS;Initial Catalog=mydatabase;User  Id=sa;Password=123" />
  </connectionStrings>
</configuration>

Answer 1

You can try

<?xml version="1.0" encoding="utf-8" ?>
 <configuration>
  <connectionStrings>
    <add name="dbConn" providerName="System.Data.SqlClient"
          connectionString="Data Source=VANYA\SQLEXPRESS;Initial Catalog=mydatabase;User  Id=sa;Password=123" />
  </connectionStrings>
  <appSettings>
    <add key="dbConn"  value="Data Source=VANYA\SQLEXPRESS;Initial Catalog=mydatabase;User  Id=sa;Password=123" />
  </appSettings>
</configuration>

Then use the second method.

Make sure you select the App.Config file in Solution Explorer and select Copy to Output Directory- in the properties window Copy Always. Now create the application and try again.

Answer 2

, , , , , :

connectionString = ConfigurationManager.ConnectionStrings["dbConn"].ConnectionString;
sqlConnection = new SqlConnection(connectionString); 

ConfigurationManager.AppSettings <appSettings>...</appSettings> .

Answer 3

You simply define a connection string in one class and call that string .....

public class Connection
    {
        /// <summary>
        /// Connection String
        /// </summary>
        public static string ConnectionString
        {
            get
            {
                return ConfigurationManager.ConnectionStrings["dbConn"].ConnectionString;
            }
        }
    }

//Returning connction string
 sqlConnection conn = new SqlConnection(Connection.ConnectionString);  

Answer 4

connectionString=global::myProject.Properties.Settings.Default.myConnectionString