Create app config file if doesn't exist C#

Question

When I try to open my app config file by

ConfigurationManager.OpenExeConfiguration(filePath);

it returns an exception, because there is no file. But I need to create this file in this case. But as I know, config file create by adding at VS like How to: Add an Application Configuration File to a C# Project

So, how to create this file in other way?

Obovoid

Why would you crate config file if user deleted it? Check if file exists before opening it (or handle exception) and use default values if config not found – Frustration

I think, user doesn't delete it. File doesn't exist at the beginning. – Obovoid

It's just a text file - you can create it just like you would any other text file. But the proper way is to include it in your project at design time. – Deck

I think the actual problem is that filePath should the path of the exe, not of the config file. Then you don't get an exception and when you call Save() the file will be created for you. – Ilse

Answer 1

If you really want to create an empty config file at runtime you can do something like this, but note that if the config file already exists this code will overwrite it:

System.Text.StringBuilder sb = new StringBuilder();
sb.AppendLine("<?xml version=\"1.0\" encoding=\"utf-8\" ?>");
sb.AppendLine("<configuration>");
sb.AppendLine("</configuration>");

string loc = Assembly.GetEntryAssembly().Location;
System.IO.File.WriteAllText(String.Concat(loc, ".config"), sb.ToString());

Slouch

"sb.toString()" should be "sb.ToString()", otherwise perfect answer. Thanks! – Theroid

Great catch @RobVermeulen, thanks! I've edited the answer. – Slouch

This is a half answer. – Chantellechanter

You could check if the file is already there, that would make it more complete. – Theroid

Answer 2

Just go to App.config file properties and change Copy to Output Directory setting from Do not copy to Copy always (or Copy if newer). That will automatically create config file during project build.

Frustration

How to create myapp.exe.config if there is no App.config in project? – Obovoid

@ArtemKyba why not simply add App.config to project? – Frustration

Client wants without adding:) – Obovoid

Answer 3

This file is needed by your application as you need to access it. The best way is to add it with Visual Studio as you wrote it. You have to ensure that it is properly deployed on the target machine at setup.

Then if it is not present on disk at runtime, it's a good behaviour to crash. You can display a message to the user (catch the exception).

Mallette

Answer 4

Why would you want to create it any other way? Is it to make sure you always have a config file, even if the user deletes it? And why would a user do that? Oh never mind.

If you want to make sure there's always a config file, you can create it yourself if it isn't there:

if (!File.Exists(configFilePath)) ...

Config files are just XML. So you could create a new file and populate it with default data, right before you want to read a key from it.

However one would expect a user not to delete a config file. Just sayin'.

Profitsharing

This kind of solution always smells like race condition; .NET Framework ignores TxF. – Chantellechanter

Answer 5

For those who are looking the answer in 2022, app.config will be created automatically if you will change the .NET Target Framework in Project properties

Inviolate

Answer 6

To add an application configuration file to a C# project

On the menu bar, choose Project > Add New Item.*

The Add New Item dialog box appears.

Expand Installed > Visual C# Items, and then choose the Application Configuration File template.

In the Name text box, enter a name, and then choose the Add button. A file named app.config is added to your project.

Annabelannabela

I'm not sure we need you to cut and paste the Ms docs into an answer. A simple comment to the link would of sufficed – Elfreda

It also totally misses the point of the question... – Elfreda