How to fix Object reference not set to an instance of an object MySql Connection Issue

Question

I'm creating a Application that's utilizing mysql as a database, however, when I run the program I keep getting this error:

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

On line 29 in the private class registerUser() where it begins as String connString =.... is where the problem is how dow I fix it?

private void registerUser()
{
    String connString = System.Configuration.ConfigurationManager.ConnectionStrings["SportsDBConnString"].ToString();

    conn = new MySql.Data.MySqlClient.MySqlConnection(connString);
    conn.Open();
    queryStr = "";

    queryStr = "INSERT INTO sportsdbmlb.userregistration (firstname, middlename, lastname, email, username, password )" +
        "VALUES('"+firstnameTextBox.Text + "','"+ middlenameTextBox.Text +"','" + lastnameTextBox.Text + "','" + emailTextBox.Text +
        "','" + usernameTextBox.Text + "','" + passwordTextBox.Text + "')";

    cmd = new MySql.Data.MySqlClient.MySqlCommand(queryStr, conn);

    cmd.ExecuteReader();

    conn.Close();
}

Here is my Web Config. <connectionStrings> <add name="SportsDBConString" connectionString="server=127.0.0.1;User ID=sportsdbappuser;Password=sportsdbappuser2014;Database=sportsdbmlb;" providerName="MySql.Data.MySql.Client"/> </connectionStrings> — user2350911
– user2350911, Commented Jul 25, 2015 at 16:15

Dacker · Accepted Answer · 2015-07-25 06:18:12Z

I think you don't have a connectionString in your App.config or your Web.config.

If you want to fix your issue you should at least do no 1:

add that configuration
you can also add a null check on the setting. In this case if it's coming from your App.config/Web.config and if you add it now, it will probably never miss anymore.

Add the configuration in App.config/Web.config depending on whether you build a console application or a web application:

  <?xml version='1.0' encoding='utf-8'?>
  <configuration>
    <connectionStrings>
      <add name="SportsDBConnString" providerName="System.Data.YourProviderName" 
           connectionString="Valid Connection String;" />
    </connectionStrings>
  </configuration>

Add a null check:

if (System.Configuration.ConfigurationManager.ConnectionStrings["SportsDBConnString"] != null) {
    String connString = System.Configuration.ConfigurationManager.ConnectionStrings["SportsDBConnString"].ConnectionString;
    //Do other logic here or move connString declaration outside this if

}
else {
    throw new Exception("Missing ConnectionString SportsDBConnString in App.config/Web.Config");
}

KV Prajapati · Accepted Answer · 2015-07-25 05:59:18Z

0

Use ConnectionString property.

String connString = System.Configuration
                          .ConfigurationManager
                          .ConnectionStrings["SportsDBConnString"]
                          .ConnectionString;

answered Jul 25, 2015 at 5:59

KV Prajapati

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