Develop Reference

Using app.config correctly

In several C# projects I have been using an app.config file to pass various settings to my program, settings like connectionstrings, power levels etc.
However sometimes I have come in situations where the settings aren't updated as expected and I have concluded that I am not that well informed with the proper use of app.config file.
Example:
Replacing the .exe file with a new version (where settings are different) to the output directory without changing the exe.config, results in the program seeing the hard-coded settings and not the settings of the existing .exe.config
So my Questions are:
What is the exact role of exe.manifest file
Every time I create a new .exe do I have to paste in the output folder anything else except the .exe file?
Whats the difference in obtaining the setting value by: ConfigurationManager.'settingName'... rather than:
Properties.Settings.Default.'settingName'?
What is the role of app.config build action?
Sorry If I am asking too much in a single Question.

The app.config file is a file that gets a special treatment when running the associated application. If you executable is named MyApp.exe the app.config file should be named MyApp.exe.config. The role of the app.config build task is to copy the file named app.config in your project to MyApp.exe.config in the output directory.
.NET provides ways to read the contents of the file (it is in XML format) and various parts of .NET will look for different sections in this XML to provide configuration.
A widely used section is the settings section you refer to as Properties.Settings.Default. This section plays together with Visual Studio that provides an editor for application settings. The settings are accessed in the code by using a generated class. Adding a setting will add a property to this class and this property is initialized from a value in the app.config file.
In the Visual Studio editor you can set a value for the setting and you can think of this as a default value for the setting. However, if you overwrite the value in the app.config file the later will take precedence. This allows you to modify the app.config file after installation and rerun the application with a modified setting.
You can also access application settings the app.config file using other methods, but in my oppinion using the Visual Studio editor and the code generated class is the best way to do that.
I am not sure I fully understand the problem that you experience. If you update MyApp.exe and leave MyApp.exe.config intact you should not see a change in the settings used by the application (unless of course you have renamed or changed some settings).
The manifest file provides information about side-by-side assemblies and can be used to request elevated privileges among other things. This is not related to the app.config file.

There quite a few resources about that.
See http://msdn.microsoft.com/en-us/library/ms229689%28v=vs.90%29.aspx
and the (better) overview: http://msdn.microsoft.com/en-us/library/k4s6c3a0%28v=vs.110%29.aspx
app.config is a very powerful tool. It addresses many issue like versioning, migration, upgrading etc. but this requires some in-depth reading from the links above.

Maybe one thing you could do, if you want to copy only .exe file every time you build your app, is make a settings.ini or settings.txt file, put your parameters in this file (that are not secret of course) and read all your settings from there when you start your app.
You can put all your connection string logic in your login form if you have one...

Modifying App.config in Program Files directory

Kind of a two part issue.
I developed an app which reads from and writes to an App.config.
The application is installed in Program Files by my MSI installer.
It works fine on my Win7 computer but I have users on Win7 that get Access Denied when writing to this App.config.
I am writing to the app.config using the below code:
Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
config.AppSettings.Settings["Endpoint"].Value = endpointTxtBox.Text;
config.Save(ConfigurationSaveMode.Modified);
Why don't I get this issue on my development pc? I have tried both with a local admin and normal local user account.
How do I relocate the App.config to an unprotected directory?

Cathal,
You should not have to move the app.config in order to let your users save their application settings; .NET already has support for saving user-scoped app settings in user-writable storage baked in! You can even specify the default user settings in the app.config file.
Check this link for details:
http://msdn.microsoft.com/en-us/library/8eyb2ct1(v=vs.110).aspx
Note that making use of a strongly-typed .NET Settings class rather than the raw, more weakly-typed AppSettings NameValueCollection. (The settings can still stored in the app.config, though.)
You can create a Settings file in VS (the template is called "Settings file" in VS).
A couple of things confused me about Settings files at first, so I thought I would point them out to you:
1) First: the .settings file. The VS designer lets you define your app settings, their types, and their scopes (i.e. user or application). This is the file the designer modifies when you user the designer, but runtime configuration changes will never be written to this file. It defines your app settings and their default values. That's it. I didn't get that at first when I was trying to wrap my head around Settings files.
Also, notice that the build action on the .settings file is set to SettingsSingleFileGenerator.
2) The .designer.cs file. VS/MSBuild generates this file at build-time for you because the build action on the .settings file is set to SettingsSingleFileGenerator. The class that it generates is a strongly typed wrapper for your configuration properties, and you can use it equally well for your application-scoped and user-scoped properties.
3) The runtime settings that your Settings class wraps are still stored in the app.config.
4) User settings are stored underneath that user's AppData\Local directory so that they have full read/write permissions.

I had a couple of other ideas, if what you need to do really is let the user modify the global application settings for all users.
Externalize some of your configuration by using the configSource attribute. You store the entire
appSettings section, for instance, in a separate file by doing this:
<appSettings configSource="....\file.config" />
Here are the docs for that feature: http://msdn.microsoft.com/en-us/library/ms228154(v=vs.85).aspx
I believe you can manually load a config file anywhere you want using the System.Configuration.ConfigXmlDocument class. Construct one using the no-arg constructor and then call its Load(String filename) method.
Store your configuration in the registry rather than the filesystem by implementing a custom SettingsProvider.

Allowing a Windows Service to be configured

I have a Windows Service that I'm creating and I'm wondering what options are available in order for me let developers configure the service.
The service is part of an over all larger open source project and hence the service is going to be installed on lots of different machines.
Normal I would use a web/app.config for this but I'm not sure if this is possible.
Hence I am looking to so how others handle this case.

you do as you expect. You use the app.config, which will be renamed to <exeName>.configwhen the project is built and then <exeName>.config will be read by the service called <exeName>.
Settings are applied in a layered way and may come from other configuration files on the machine, such as machine.config. You can read about how configuration is handled on MSDN
EDIT
In response to comment: A service will only read the config when it starts (for perf reasons). If you want to reload the config file later, you need to handle that yourself I think.
You could read the last modified date/time of the config file to determine if the file has been changed, or setup a file system watcher and then tell the configuration manager to reload that section again next time it is read, by calling ConfigurationManager.RefreshSection("appSettings") and that section will be reloaded from disk when you next access it. See the ConfigurationManager MSDN docs

You can just use a .config file with the same name as the exe that is the service.
If your service runs as MyService.exe, it's config file would be MyService.exe.config.
In Visual Studio, just add an Application Configuration file. This will add an app.config file to the project.
You can then access things like AppSettings and ConnectionStrings using the ConfigurationManager class, just like you do with ASP.Net applications.

Why wont my application read my MyApplication.dll.config file?

I'm trying to use application settings with a C#.NET project I am working on. But I can't seem to get it to return anything other then the default values. Through the project properties I've added a single setting, DBConnectionString, and set its value to a connection string I want to use. Its scope is set to "application".
Doing this created a number of files including Settings.settings, Settings.Designer.CS, and app.conifg. From what I understand the two Settings.* files define a custom Settings class that derives from ApplicationSettingsBase. The Settings class then has custom, type safe, properties that can be used to set and retrieve each setting. The app.config file is a XML file that stores the actual settings values.
When I build my project it looks like the app.config file is copied to the target directory as MyApplication.dll.config. My program runs fine and is able to use the default connection string.
Next I tried to edit the MyApplicaiton.dll.config file to change the connection string. I ran my program again, but it continued to use the default value. I noticed that in my Settings.Designer file there is a DefaultSettingValueAttribute with the original default string. I tried removing this attribute, but then when I tried to retrieve the connection string setting it just returned null.
This is the code I'm using to read the connection string.
string conn = Properties.Settings.Default.DbConnectionString
What am I doing wrong? How can I get it to return the value in the settings file and not the default value?
Update:
Sorry I should have mentioned this. I'm actually writing a plug-in for another application through a public API. So my project is a DLL not an EXE.

You cannot read settings from *.dll.config files. If you library needs any special settings you need to put them in your app.config or web.config files.
EDIT: You can include the external config files in the main application or web config file. Look here for details.
This question discusses how to manage configuration files for large projects.

Settings files and .config files are different things (I do not know why VS automatically added a .config when you created a Settings file). But, the settings file is compiled into a class and is referenced like you said. If you decompile the dll with .NET reflector the Settings class will be in there. It is used for holding constant values or external resources. For example: error message strings, icons, or images.
The config file is for settings which can change frequently or between environments (dev, test, prod). For a connection string you should use the <connectionStrings> section of the config file. And the property can be referenced using System.Configuration.ConfigurationManager[ "connectionStringName" ].
However, from your original post it looks like your .dll is going to be used in a larger project (either an .exe of web project). One thing to note is that all projects only use one .config file. And that is the config file for the main project. Websites the web.config file, and exe's use XXX.XXX.XXX.exe.config (as you saw, *.exe.config files are renamed copies of the app.config files). dll's do not have usable config files. All dll's will look at the main project's .config file to retrieve information.
If your connection string is never going to change then by all means use the Settings file. Otherwise, use a config file and let the developer of the main project determine what to populate the connection string with.

C# Settings xml file location

I have a project that reads in a file based on a value in a C# Setting class. This value however changes from machine to machine and Id rather not ask the user the first time the program is run as its a corporate environment, instead Id like it to be set in the installer, but where is the file located? Is there an easier method?
This is a visual studio addin not a standalone program

From your post it appears you have a windows application? , you can store an initial value in the application config, you can make an installer in Visual Studio and write custom actions that can write values to the file on first install in you install project.

The configure file is the easiest way to do what you are asking, however it is NOT the best. In fact it is recommended Not to use .config files for such cases.
whenever users install an 'update', there is a risk of overwriting their existing changes.
some businesses might have policy restrictions on the .config files.
the user cannot easily move his settings from one PC to another.
From my own experience, using XML, MS-Access, Registry or text files to store user settings has proven more useful than using the .config files.

I believe you are talking about designer-generated settings (the .settings file)?
The exact path usually contains some sort of a Hash (check this link). I usually have my own settings class which I serialize to and from xml using XmlSerializer, which gives me more freedom (I think C# settings files don't allow you to add custom enums, for example, or they make it a bit harder to do it than simply adding them to the .settings file).
However, maybe there is no need to set values during installation? For example, you could add a FirstStartup setting (set to true initially), which you can read when your App is started for the first time, and then set it to false. That way you can set your default settings when you detect a "first startup".

You will certainly need some sort of custom action at the end of your installer. You haven't mentioned what technology you're using to deploy your application so I will refrain from giving any specific guidance.
I recommend setting the value in your App.config. This is an xml file which will be named MyApplication.exe.config in the same directory as your application. Add it to your installer if it is not there already. In your installer, add a new setting:
<configuration>
<appSettings>
<add key="MySetting" value="My Value"/>
</appSettings>
</configuration>
In your code, retrieve the setting:
String setting = ConfigurationSettings.AppSettings["MySetting"];
If this is a machine-wide setting, this installer is the right place to set this. If you do it on the first execution you will run into a host of problems with permissions on the files and directories if the first person to run the app is a user with limited permissions.

Registry or an INI file or a XML file whatever suits you best.

Best option would be registry. Istalling the application will require Admin access so writing to the registry during installation will not be an issue.
More over if some one accidently deletes the ini or settings file then the program might stop working.

You said that this is for a corporate environment. You can create an administrative template for group policy to set the default in the registry. Then, your program can just query that one registry value if the default hasn't already been set.

I personally would never use web.config or app.config. Just read your own xml file, have a look at my post on this:
http://www.picnet.com.au/blogs/Guido/post/2009/09/10/XML-Settings-Files-No-more-webconfig.aspx
Thanks
Guido

To answer the "Where is the file located" bit of the original question for those interested (I'm assuming that the "settings file" in question is the "Settings File" item available from the "Add New Item" dialogue).
In Win7 (and probably all the other ones) the settings file will generate under the path:
C:\Users\[user]\AppData\Local
The folder structure from here on out depends on your AssemblyInfo and build information, the "AssemblyCompany" field (if populated) is used for the top-most folder, beneath this is a folder copying the application executable name, followed by the build and then finally the settings file (named "*.config").
In my case, the complete path is as follows:
C:\Users\[user]\AppData\Local\[company_name]\Application.exe_StrongName_zx0v1qxyoass4d0z3mtwe3vbrhaehkjg\0.0.5812.21662\user.config

My case is different, my project is a class library (dll) which have the app.config file. I decided to create 4 application settings variables (title, url, limit, rate). To create this, i right-click ont he project --> Properties --> Settings. this values you can retrieve in code using this command --> Settings.Default.title, ...etc
the problem is let say i instantiate 5 objects (same object for example MyProject.MyClass) from this library, i want the instance be able to have its own settings. i mean each of the instance may have their xml setting file. can this be done?