Develop Reference

Custom user configuration in C# application

Let's say I have a command line application that needs to reference some form of a user configuration file. Furthermore, the values contained within this file are to only be updated by the user manually -- there won't be any ways of updating the configuration file within the application, nor will the application seek out any inputs once started. If a configuration listing is missing from the configuration file, a default value should be used instead.
I understand that Visual Studio / .NET Framework offer tools for creating such constructs (i.e. Settings and App.configs), but I'm not sure I'm using them correctly -- or if I should be using them at all.
I created a Settings file and threw in a couple of default settings (e.g. SomeBooleanFlag is a bool with a default value of 'False'). This addition of course was reflected within my App.config. However, here is where the dilemma lies: how should I read from the App.config?
Currently, I've created a class to abstract away the configuration manager / settings stuff:
class AppSettings
{
public static bool SomeBooleanFlag
{
get
{
try
{
string rawValue = ConfigurationManager.AppSettings["SomeBooleanFlag"];
bool userSetSomeBooleanFlag;
bool userValueParsed = bool.TryParse(rawValue, out userSetSomeBooleanFlag);
return (userValueParsed) ? userSetSomeBooleanFlag : Settings.Default.SomeBooleanFlag;
}
catch
{
return Settings.Default.SomeBooleanFlag;
}
}
}
}
Which then gives me the ability to write:
if (AppSettings.SomeBooleanFlag)
{
/* Do Something... */
}
However, this does not seem like a clean way to approach the problem I stated above. Any help would be greatly appreciated!

Instead of coding your own Application Settings wrapper, you can reuse the functionality built into Visual Studio to generate this wrapper for you. See How to: Add or Remove Application Settings and How To: Read Settings at Run Time With C#. In addition to specifying the type of the setting you can also indicate the scope (User or Application).
Following the steps in the aforementioned articles, it will add the settings to your App.config file, below is an example:
<configuration>
...
<applicationSettings>
<ConsoleApplication1.Properties.Settings>
<setting name="TestKey" serializeAs="String">
<value>TestValue</value>
</setting>
</ConsoleApplication1.Properties.Settings>
</applicationSettings>
...
</configuration>
And you can access these settings as follows:
string s = Properties.Settings.Default.TestKey;

ConfigurationManager.AppSettings Returns Null In Unit Test Project

I have a C# unit test project with application settings in the app.config file. I am testing a class that exists in a different project. That class depends on both, ConfigurationManager.AppSettings and ConfigurationManager.ConnectionStrings.
The project that the class being tested resides in does not have an app.config file. I would have thought that because the class is being instantiated in the context of the unit test project that it would use the unit test project's app.config file. Indeed, that does seem to be the case for the connection string.
The class retrieves the connection string without any issues. However, when the class tries to retrieve any application settings the configuration manager always returns null. What is going on here?
Edit 1
I thought maybe it would be a good idea to try load some settings in the test project to see what happens. I tried to load the setting in the unit test immediately before calling the code that instantiates the class in the external project. Same result, nothing. I guess I can exclude the other project from the equation for the time being.
Here is an excerpt from my config file:
<configSections>
<sectionGroup name="applicationSettings"
type="System.Configuration.ApplicationSettingsGroup, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" >
<section name="MyNamespace.Properties.Settings"
type="System.Configuration.ClientSettingsSection, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"
requirePermission="false" />
</sectionGroup>
</configSections>
...
<applicationSettings>
<MyNamespace.Properties.Settings>
<setting name="Bing_Key"
serializeAs="String">
<value>...</value>
</setting>
</MyNamespace.Properties.Settings>
</applicationSettings>
and here is how I am attempting to load the setting:
string test = System.Configuration.ConfigurationManager.AppSettings["Bing_Key"];

Consider refactoring your code that accesses the config to use a wrapper. Then you can write mocks for the wrapper class and not have to deal with the importing of the configuration file for the test.
In a library that is common to both, have something like this:
public interface IConfigurationWrapper {
string GetValue(string key);
bool HasKey(string key);
}
Then, in your libraries that need to access config, inject an instance of this interface type into the class that needs to read config.
public class MyClassOne {
private IConfigurationWrapper _configWrapper;
public MyClassOne(IConfigurationWrapper wrapper) {
_configWrapper = wrapper;
} // end constructor
public void MethodThatDependsOnConfiguration() {
string configValue = "";
if(_configWrapper.HasKey("MySetting")) {
configValue = _configWrapper.GetValue("MySetting");
}
} // end method
} // end class MyClassOne
Then, in one of your libraries, create an implementation that depends on the config file.
public class AppConfigWrapper : IConfigurationWrapper {
public string GetValue(string key) {
return ConfigurationManager.AppSettings[key];
}
public bool HasKey(string key) {
return ConfigurationManager.AppSettings.AllKeys.Select((string x) => x.ToUpperInvariant()).Contains(key.ToUpperInvariant());
}
}
Then, in the code that calls your class.
//Some method container
MyClassOne dataClass = new MyClassOne(new AppConfigWrapper());
dataClass.MethodThatDependsOnConfiguration();
Then in your test, you are free from dependency bondage. :) You can either create a fake version that implements IConfigurationWrapper and pass it in for your test, where you hard-code the return values from the GetValue and HasKey functions, or if you're using a mocking library like Moq:
Mock<IConfigurationWrapper> fakeWrapper = new Mock<IConfigurationWrapper>();
fakeWrapper.Setup((x) => x.GetValue(It.IsAny<string>)).Returns("We just bypassed config.");
MyClassOne testObject = new MyClassOne(fakeWrapper.Object);
testObject.MethodThatDependsOnConfiguration();
Here is an article that covers the concept (albeit, for web forms, but the concepts are the same): http://www.schwammysays.net/how-to-unit-test-code-that-uses-appsettings-from-web-config/

You mentioned settings in the project properties. See if you can access the setting this way:
string test = Properties.Settings.Default.Bing_Key;
You may need to get the executing assembly of where the project settings file is defined, but try this first.
EDIT
When using Visual Studio's project settings file, it adds stuff to your app.config and creates the app.config if it is not present. ConfigurationManager CAN'T touch these settings! You can only get to these specific generated project.settings file from using the above static method. If you want to use ConfigurationManager, you will need to hand write your app.config. Add your settings to it like so:
<appSettings>
<add key="bing_api" value="whatever"/>
</appSettings>

If you're using .NET Core your problem could be a known issue caused by the fact that the test process runs as testhost.dll (or testhost.x86.dll), which means the runtime config file is expected to be named "testhost.dll.config" (or "testhost.x86.dll.config"), instead of the app.config output (ex: "MyLibrary.Tests.dll.config").
To fix it, add the code below to your project file (.csproj, etc) inside of root node <Project>. During build, two copies of app.config will be put in the output directory and named "testhost.dll.config" and "testhost.x86.dll.config", which will get your app settings working again. (You only need 1 of these files but it's safer to include both.)
<Target Name="CopyCustomContent" AfterTargets="AfterBuild">
<Copy SourceFiles="app.config" DestinationFiles="$(OutDir)\testhost.dll.config" />
<Copy SourceFiles="app.config" DestinationFiles="$(OutDir)\testhost.x86.dll.config" />
</Target>
I recommend app.config only as a temporary solution. If you're like me you might have run into the problem while upgrading a .NET Framework project to .NET Core and needed a quick fix. But don't forget to look into the new, more elegant solutions provided by .NET Core for storing app settings.

And then he screamed "NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO".
Cite: I have a C# unit test project with application settings in the app.config file. I am testing a class that exists in a different project. That class depends on both, ConfigurationManager.AppSettings and ConfigurationManager.ConnectionStrings.
You don't do this. EVER!!!! Why? because you have now created a dependency. Instead, use dependency injection so the class can do its work without having to peak into the configuration file that belongs to the application.

Invalid Resx file. Could not load type error why?

I'm getting designer error on code:
The Component i'm willing to define a List of properties for:
using System.Collections.Generic;
using System.ComponentModel;
using System.Windows.Forms;
namespace TestProjectForProperty.Test
{
public class MyTreeView : TreeView
{
private List<TypeDescriptorBase> _descriptorsAvailable = new List<TypeDescriptorBase>();
[DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
public List<TypeDescriptorBase> DescriptorsAvailable
{
get { return _descriptorsAvailable; }
set { _descriptorsAvailable = value; }
}
}
}
The Descriptor itself:
using System;
namespace TestProjectForProperty.Test
{
[Serializable]
public class TypeDescriptorBase
{
public string Name { get; set; }
public override string ToString()
{
return Name;
}
}
}
I am getting the following error if i try to use the component for example on a form and add any items on the property sheet or in the component's constructor to the DescriptorsAvailable property
Error 1 Invalid Resx file. Could not load type
System.Collections.Generic.List`1[[TestProjectForProperty.Test.TypeDescriptorBase,
TestProjectForProperty, Version=1.0.0.0, Culture=neutral,
PublicKeyToken=null]], mscorlib, Version=4.0.0.0, Culture=neutral,
PublicKeyToken=b77a5c561934e089 which is used in the .RESX file.
Ensure that the necessary references have been added to your project.
Line 134, position 5. ...\visual studio
2010\Projects\TestProjectForProperty\TestProjectForProperty\Form1.resx 134 5 TestProjectForProperty
In the Resx file there is data field with base64 encoded stuff inside when this error is present.
I have been searching for an answer, but the best i got is to restart everything, it didn't help me, do you guys have any suggestions? I'm using .net 4 client and visual studio 2010

In my experience, this is due to a change of version of a referenced library, or a change of the lib itself, which contains the backing type of a property you have defined in your user control. The solution is to "force" the visual studio designer to re-initialize it's designer code for that type, and not expect to retrieve a "canned" version of it from the .resx file of the control.
1) Delete the offending data section in the .resx file of your control. This will be a section in the xml of the .resx file associated with your user control, which has a node: <data></data> - the name attribute will be set to whatever you've named that object in the properties of whatever you added this type to. The <data>/data> section contains a base64 encoded string that is the encoded form of the name and version of the library the type comes from. This is where the problem ism, because it now contains an encoded version of the library and/or version number you are no longer referencing in order to include the type. Delete the entire <data>/data> section, from opening to closing tag, save the change and close the file. Now the "artifact" is gone.
2) Now find the place in the designer file for your control, where the type is instantiated; this is initialization code generated for you by visual studio, and it is the place that is expecting to load a "canned" definition of the type from the base64 encoded string contained within the .resx file. The line will look something like this:
this.myCtrlFoo.MyPropertyFroo = ((MyNamespaceFoo.MyTypeFoo)(resources.GetObject("myCtrlFoo.MyPropertyFroo")));
...now just replace the resources.GetObjec call with the instantiation of a new instance of the appropriate type like so:
this.myCtrlFoo.MyPropertyFroo = ((MyNamespaceFoo.MyTypeFoo)(new MyNamespaceFoo.MyTypeFoo()));
...now save the change to the file, close it, rebuild, and everything should now build & run OK.

Put the MyTreeView and TypeDescriptorBase classes into another project and reference it from your GUI project will resolve the issues.
I'm not sure why exactly the problem occurs - I guess it has something to do with the way the serializing process is generating the base64 string for the DescriptorsAvailable Property. Maybe somebody else can give us some insight.

I've struggled quite a bit with this; I have three user controls that all expose the same non-designer property, but for some reason, any change to two of the three would instantly cause the next build to fail with this same issue. This is in VS 2015.
I wound up having to add the following two attributes to the property that kept expanding in the resx file, and it hasn't occurred since. It works for me because they're not available in the designer anyway.
[Browsable(false)]
[DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]

For me, this error occured when I used a custom class as a property for the user control. When I switched from property to traditional get- and set- methods, the error disappeared. I guess this is because properties are already compiled at design-time, so when you build the whole project, a new version of the custom class is compiled which is separate from the one of the control, and the reference is broken.
For me, with the custom class Inventory, all I had to do was to switch from this property-based approach:
public Inventory Resources {get;set;}
to this method-based approach:
private Inventory resources;
public Inventory getResources() { return resources; }
public void setResources(Inventory newResources) { resources = newResources; }
I hope this helps someone, as I've been spending some hours on figuring it out.

In my case I've got the error : "error MSB3103: Invalid Resx file. The specified module could not be found" executed in a light windows container based on mcr.microsoft.com/powershell instead of mcr.microsoft.com/windows:1909 (was working fine on 1909).
The error was on a ressource icon that was compressed with PNG inside.
It can be checked by opening the ressource on visual studio : Project > Properties > Ressources.resx, select icons, double click on the icon, check the end of the title that is either "..,BMP]" or "...,PNG]").
Updating the icon with an uncompressed format solve the "Invalid Resx file" issue.

I stumbled across this question today whilst looking for the solution to a similar issue.
Unfortunately none of the above worked for me, however my issue turned out to be that I had different versions of the .NET Framework for different projects. For example;
Project A - .NET Framework 4.7.2
Project B - .NET Framework 4
Where Project B was referencing Project A. Solution was simply to change the .NET Framework version of Project B to 4.7.2 (in my case) and hey presto the issue was resolved.
A shame Visual Studio doesn't provide a more helpful error message in this case, but something to look out for!

App.config multi-project access strategies

My current solution has 3 project with 2 app.config (one for common settings and another for service settings). As of now I'm simply creating static classes to act as a mediator to access values. I do this so I don't have to write ConfigurationManager.AppSettings["SomeKey"] everywhere. This works fine until you want to access an app.config file from a different project.
Here is what I'm currently doing (all properties omitted for brevity).
public class ServiceConfiguration
{
public static readonly string SyncEvery = ConfigurationManager.AppSettings["SyncEveryMinutes"];
}
How can I access an app.config file located in another project? I thought perhaps setting VS to copy the file to the output directory would do the trick however my configuration object is still null.

I can't imaging many good reasons to read another app's configuration in the first place, it just opens a can of worms that isn't worth dealing with.
Expose a class that exposes the project's configured values as properties, and access them from a consuming class.
public class FirstProjectClass
{
public static int SyncEveryMinutes
{
get { return (int)ConfigurationManager.AppSetting["SyncEveryMinutes"] };
}
}
public class SecondProjectClass
{
public void ShowConfigedValue()
{
Console.Writeline("Syncing every {0} minutes", FirstProjectClass.SyncEveryMinutes);
}
}
if you've got complex configuration requirements you can also look into custom configuration sections

ConfigurationManager.OpenExeConfiguration can be helpfull:
http://msdn.microsoft.com/en-us/library/system.configuration.configurationmanager.openexeconfiguration.aspx
Also: what Jason said - it is usually a bad idea.

Is having a global Config class a bad thing?

Currently in my personal website I'm building I'm using a global static Config class to hold everything configurable I might need to change that is semi-global. So right now it looks about like this:
public static class Config
{
public static string ConnectionString = "mongodb://localhost";
//more configuration options..
public static MongoDB.Driver.MongoDatabase GetDB(){
MongoServer server = MongoServer.Create(Config.ConnectionString);
MongoDatabase db = server.GetDatabase(Config.Database);
return db;
}
public static Markdown GetMarkdown(){
var options=new MarkdownOptions(){
AutoHyperlink=true,
AutoNewlines=false,
EmptyElementSuffix=" />",
LinkEmails=false,
StrictBoldItalic=true
};
var m=new Markdown(options);
return m;
}
}
Is using a global config class like this an anti-pattern of some sort? Also, I prefer for my connection strings to be outside of web.config. I like my web.config to be as minimal as possible.

Well of the 3 members only 1 is really config, the other two are utility really.
Having configuration in compiled code is really a pain to maintain if those configs need to be changed, since it requires a rebuild, that is really the reason for configuration files.

I do things similar to this but not for settings like connection strings. If the connection string needs to change, you need to update and rebuild your project. If you stored the connection string in your web.config, a simple update allow your app to immediately use the new setting (no recompile).

Earlz ,
Regarding your second question you can do something like this, there is no need to have all the connections or configs in web.config. You can have a separate config file and point that in the web.config file as below
<connectionStrings configSource="config\yourpath\connectionStrings.config"/>
Regarding the first question , write a common method which get the values. Load all the values to a constants file and write a helper class to get those values

The anti-pattern is that you have GetMarkdown and ConnectionString together in the same class because they are both static, yet they really have no functional relationship. GetMarkdown and GetDB both look like factory methods and they should probably be in their own classes.
The Single Responsibility Principle says you should group things together that are likely change for the same reason. It's unlikely that your database connection and markdown config will change at the same time or for the same reason.

We moved our config settings to the database. Makes it easier when moving from Dev to QA to Prod. The blog entry is here.
Related to this, we put the connection string off to the side in a WebEnvironment.config. So now we can promote our code with web.config changes and not worry about the connection string. That blog post is here.