how to read the connection string from App.config file by C#

Question

I'm using this code to read the connection string from my app.config file but it always return a null value. My App.config file is under my project. Both methods are resulting 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>

Does your project happen to be a class library project? Those do not actually use their own app.config file - you'll need to put your connection string into the hosting application (the main program or web app / web site) using your class library — marc_s
– marc_s, Commented Mar 25, 2012 at 11:52

Alexander · Accepted Answer · 2012-03-25 10:42:25Z

5

I think your problem that you try to read connection string twice, first you do it right, and second time you do it wrong, so just remove second line:

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

ConfigurationManager.AppSettings used to access <appSettings>...</appSettings> section of the config.

answered Mar 25, 2012 at 10:42

Alexander

1,3171 gold badge16 silver badges34 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Jay Over a year ago

Your are overwriting connectionString by re-assigning it. Remove the 2nd assigment of connectionString and you will be fine.

PraveenVenu · Accepted Answer · 2012-03-25 10:54:15Z

4

Can you please 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 the solution explorer and in the property window select Copy to Output Directory to Copy Always. Now Build the application and try again.

See the screenshot

edited Mar 25, 2012 at 10:54

answered Mar 25, 2012 at 10:42

PraveenVenu

8,3674 gold badges32 silver badges39 bronze badges

Comments

Akash KC · Accepted Answer · 2012-03-25 10:49:13Z

1

You simple define 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);

answered Mar 25, 2012 at 10:49

Akash KC

16.4k6 gold badges41 silver badges59 bronze badges

Comments

Stecenko Ruslan · Accepted Answer · 2012-03-25 10:53:54Z

1

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

answered Mar 25, 2012 at 10:53

Stecenko Ruslan

2931 silver badge3 bronze badges

Collectives™ on Stack Overflow

how to read the connection string from App.config file by C#

4 Answers 4

1 Comment

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

1 Comment

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related