Parameter initialization using App.config and reflection

Question

In a project I have lots of classes that need some parameters whose values I can put in the App.config. Most of them can be static readonly variables. I suppose a smart and universal way to assign them the right value form App.config is to code their class and name in App.config and then use the reflection. This kind of problem should be quite general so I'm surprised I didn't find some already developed code which implements it. Am I on the wrong way ? Do you have something to suggest ? An open source project to look at ? Thanks Filippo

Filippo Martinelli · Answer

Using Resources ? I cannot understand what you mean. Can you give some details on how you would use resources ? I summarize my goals: - the possibility to change some parameters from a configuration file without the need to recompile the code - leave my classes as clean as possible - no need to change the code when I add another class which has some parameters to tune. bye Filippo

Rajeswari nathan · Answer

Why you dont go for Resources...?

Filippo Martinelli · Answer

Thanks but I was looking for something different. Finally I decided to write two lines of code fitted only to my current need. Suppose in the app.config file there is a section with name value pair. The name are built as follows: full class name/variable name and all avariables are integer. The following piece of code initializes them using reflection public void initializeCommParameters() { NameValueCollection nameValueCollection = (NameValueCollection) ConfigurationManager.GetSection(Interporto/ComunicationParam); foreach (string key in nameValueCollection.Keys) { try { int index = key.IndexOf('/'); string className = key.Substring(0 index); string variableName = key.Substring(index + 1); int value = Convert.ToInt32(nameValueCollection[key]); Type classType = Assembly.GetExecutingAssembly().GetType(className); FieldInfo myField = classType.GetField(variableName BindingFlags.Static | BindingFlags.Public); myField.SetValue(null value); } catch (Exception e) { // do something } } } The advantage of this approach are as far as I know the following: - I don't need to put NameValueCollection and ConfigurationManager everywhere in my classes - adding a new class with an integer variable to initialize I don't need to change the already written code. I simply add the right row in the app.config. This code snippet works only with integer variable but it is not too complicated to pass the variable type with an additional filed in the app.config. Perhaps spring for net does something similar... Bye Filippo

Serban Cosmin · Answer

Hy In my application I use the ConfigurationManager class which simply reads the string value that you specify in App.config for your property like this: string someID = System.Configuration.ConfigurationManager.AppSettings [SomeID]; The AppSettings property is indexed by the values you define in App.config and as you see it is very easy to call from your code. In App.config the entry looks like this:  and what you get for your property is the MyID value. For a more extensive example using ConfigurationManager please vesit : http://msdn.microsoft.com/en-us/library/system.configuration.configurationmanager.aspx. Hope this helps.