Reputation: 271
I have an application that need to check to the database if a particular code exists; if it does exist, then have to load the corresponding value of that code else return null.
I don't want to hit the database for each code(running about 200.000 codes ).
so i got this small app to test the app.conf
public static void setAppSetting(string key, string value)
{
Configuration config = ConfigurationManager.OpenExeConfiguration(System.Reflection.Assembly.GetExecutingAssembly().Location);
if (config.AppSettings.Settings != null)
{
config.AppSettings.Settings.Remove(key);
}
config.AppSettings.Settings.Add(key, value);
config.Save(ConfigurationSaveMode.Modified);
}
public static string getAppSetting(string key)
{
try
{
Configuration config = ConfigurationManager.OpenExeConfiguration(System.Reflection.Assembly.GetExecutingAssembly().Location);
return config.AppSettings.Settings[key].ToString();
}
catch (Exception ex)
{
throw ex;
}
}
private static void loadKeysValues()
{
using (SqlConnection Gcon = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["constr"].ConnectionString))
{
//Open Connection
Gcon.Open();
using (SqlCommand sqlCmd = new SqlCommand("SELECT key,value FROM tables", Gcon))
{
using (SqlDataReader reader = sqlCmd.ExecuteReader())
{
if (reader.HasRows)
{
while (reader.Read())
{
System.Console.WriteLine(reader.GetString(0) + " , " + reader.GetString(1));
setAppSetting(reader.GetString(0), reader.GetString(1));
}
}
} // End of SqlDataReader
} // end of SqlCommand
}
}
static void Main(string[] args)
{
System.Console.WriteLine("Loading.........");
loadKeysValues();
System.Console.WriteLine("Completed");
System.Console.WriteLine("Input a key to get its value");
var input = System.Console.Read().ToString();
System.Console.WriteLine(getAppSetting(input));
System.Console.ReadLine();
}
But I got an error with the getAppSetting() at this line:
return config.AppSettings.Settings[key].ToString();
Error: Object reference not set to an instance of an object.
Plz help
Upvotes: 1
Views: 954
Reputation: 399
ToString() method don´t return the value, try with Value property:
return config.AppSettings.Settings[key].Value;
Upvotes: 1
Reputation:
Make sure that the value isn't null. Try this:
if (config.AppSettings.Settings.ContainsKey(key) &&
config.AppSettings.Settings[key] != null)
{
return config.AppSettings.Settings[key].ToString();
}
Upvotes: 2
Reputation: 151
Most likely you're trying to access a setting that doesn't exist. You could handle that exception in your catch block and return null in that case.
Upvotes: 1