asked on
Writing to App.Config File in C#
All,
I am trying to create a application via C# that writes a value to the AppConfig file. But I am often prompted with this error message when I run the program the first time. However, when I run it after the first run, it'll execute fine. Can someone explain what is happening? I try to set the debugger , but I assume it's probably a timing issue.
I tried this by executing the .exe file in the bin folder of the program so there's no issues writing to the config file.
Error:
Object reference not set to an instance of an object.
App.config
-------------
Program.cs
----------
MethodHelper.cs
----------
I am trying to create a application via C# that writes a value to the AppConfig file. But I am often prompted with this error message when I run the program the first time. However, when I run it after the first run, it'll execute fine. Can someone explain what is happening? I try to set the debugger , but I assume it's probably a timing issue.
I tried this by executing the .exe file in the bin folder of the program so there's no issues writing to the config file.
Error:
Object reference not set to an instance of an object.
App.config
-------------
<?xml version="1.0"?>
<configuration>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.2"/>
</startup>
<appSettings>
<add key="OrderNumber"/>
</appSettings>
<system.web>
<membership defaultProvider="ClientAuthenticationMembershipProvider">
<providers>
<add name="ClientAuthenticationMembershipProvider" type="System.Web.ClientServices.Providers.ClientFormsAuthenticationMembershipProvider, System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" serviceUri=""/>
</providers>
</membership>
<roleManager defaultProvider="ClientRoleProvider" enabled="true">
<providers>
<add name="ClientRoleProvider" type="System.Web.ClientServices.Providers.ClientRoleProvider, System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" serviceUri="" cacheTimeout="86400"/>
</providers>
</roleManager>
</system.web>
</configuration>
Program.cs
----------
public class PurchaseOrder850
{
static public void Main(string[] args)
{
string OrderNo = 123;
MethodHelper.ModifyAppConfig(OrderNo);
}
}
MethodHelper.cs
----------
public static void ModifyAppConfig(string value)
{
try
{
Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
config.AppSettings.Settings["OrderNumber"].Value = value;
Thread.Sleep(TimeSpan.FromSeconds(3)); // added this so there's time for the file to be updated, not sure if necessary.
config.Save();
ConfigurationManager.RefreshSection("appSettings");
}
catch (System.IO.IOException e)
{
Console.WriteLine(e.Message + " key value passed for App Config: " + value);
}
}
C#.NET Programming
Last Comment
teknovation
ASKER
Can't tell , since it fails randomly, whenever I debug it never fails.
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ASKER
Thanks!
ASKER
Actually this didnt work! I got the error again this morning
Can you debug it?
Also you could make it write detailed errors to the log so you could have al'the details whenever the error occurs
Also you could make it write detailed errors to the log so you could have al'the details whenever the error occurs
ASKER
can you assist with sample code?
wrap your code in try...catch:
and make sure you add "using System.IO" at the top of your code file.
The code above is not tested as I don't have access to Visual studio at the moment so you might need some tweaks
try {
if(config.AppSettings.Settings["OrderNumber"]!=null)
config.AppSettings.Settings["OrderNumber"].Value = value;
else
config.AppSettings.Settings.Add("OrderNumber", value);
} catch (Exception ex) {
string path=Path.Combine(Application.StartUp, "myLog.txt");
if (! File.Exists(path))
File.Create(path);
using (StreamWriter w = File.AppendText(path))
{
w.WriteLine(ex.Message + ":" + ex.StackTrace);
}
}
and make sure you add "using System.IO" at the top of your code file.
The code above is not tested as I don't have access to Visual studio at the moment so you might need some tweaks
ASKER
So i couldnt get your code to work but here's some new interesting finds.
When I open up the config file - the keys exist
<add key="OrderNumber" value="5924524" />
Then I decided to remove the key from the app config file and run the app and it still works and rewrites because it's not there as expected.
So it's mainly when the computer first reboots and runs the app for the first time and it fails when writing to the app config file. That is so strange - because it will fail with the same error whether or not the Order Number key exists!
Thoughts? Could it be related to security upon rebooting?
When I open up the config file - the keys exist
<add key="OrderNumber" value="5924524" />
Then I decided to remove the key from the app config file and run the app and it still works and rewrites because it's not there as expected.
So it's mainly when the computer first reboots and runs the app for the first time and it fails when writing to the app config file. That is so strange - because it will fail with the same error whether or not the Order Number key exists!
Thoughts? Could it be related to security upon rebooting?
try adding this line
after
ConfigurationManager.RefreshSection("appSettings");
after
Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
ASKER
Didn't work, rebooted machine and still fails when running for the first time
Do you know exact line it fails on? Anything found in the log file?
ASKER
The log file didn't create could you give me the exact syntax?
could you post your updated code?
ASKER
Since the write log didnt' work, I just reverted it back.
Here's my current code:
Here's my current code:
Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
ConfigurationManager.RefreshSection("appSettings");
try
{
if (config.AppSettings.Settings["OrderNumber"] != null)
config.AppSettings.Settings["OrderNumber"].Value = value;
else
config.AppSettings.Settings.Add("OrderNumber", value);
config.Save();
ConfigurationManager.RefreshSection("appSettings");
}
catch (Exception e)
{
Console.WriteLine(e.Message + " key value passed for App Config: " + value);
}
try this:
public static void ModifyAppConfig(string value)
{
Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
ConfigurationManager.RefreshSection("appSettings");
try
{
if (config.AppSettings.Settings["OrderNumber"] != null)
config.AppSettings.Settings["OrderNumber"].Value = value;
else
config.AppSettings.Settings.Add("OrderNumber", value);
config.Save(ConfigurationSaveMode.Modified);
ConfigurationManager.RefreshSection("appSettings");
}
catch (Exception e)
{
string filePath = @"C:\Error.txt";
using (StreamWriter writer = new StreamWriter(filePath, true))
{
writer.WriteLine("Message :" + e.Message + "<br/>" + Environment.NewLine + "StackTrace :" + e.StackTrace +
"" + Environment.NewLine + "Date :" + DateTime.Now.ToString() + Environment.NewLine);
}
}
}
ASKER
No file is created in the c drive
I think the issue is that there is no entry for OrderNumber and it needs to be created first