How can I make a .NET class library read its own configuration file?

Question

I have a .NET class library that provides a set of helper functions that are used by several Web Services. This class library must store a single setting, specifically, a connection string, which need not be seen by the Web Services themselves, since they all must query the same datbase.

Unfortunately, .NET provides no means to easily read a DLL's app.config file. The only "easy" solution would be to store the connection string in every single Web Service configuration file, which is completely bollocks.

Normally, I care about code elegance, but this time I really need a solution, even if it is a hack. Is there any way to make a .NET class library have its own configuration?

---

EDIT: Technically, I could merge all those Web Services into a single Web Service. But, for business reasons (each Web Service will be sold separately), I cannot do that.

Answer 1

I think you're looking for:

ConfigurationManager.OpenExeConfiguration(string exePath)

or

ConfigurationManager.OpenMappedExeConfiguration(
    new ExeConfigurationFileMap() { 
        ExeConfigFilename = path + "app.config" 
    }, ConfigurationUserLevel.None);

Which returns a Configuration object. MSDN doc on ConfigurationManager

Try this question for how to get the DLL path.

Answer 2

A year out of date I know, but I used this method to read each of the settings:

Configuration config = ConfigurationManager.OpenExeConfiguration(Assembly.GetExecutingAssembly().Location);
ConfigurationSectionGroup csg = config.GetSectionGroup("applicationSettings");
ClientSettingsSection c = (ClientSettingsSection)csg.Sections["Add your section name here, e.g. Your.Namespace.Properties.Settings"];
foreach (SettingElement e in c.Settings)
{
    Debug.WriteLine("SETTING NAME: " + e.Name);
    SettingValueElement v = e.Value;
    Debug.WriteLine("SETTING VALUE: " + v.ValueXml.InnerText);
}

This works on a settings file created in a Class Library Project. The settings file should be named "YourLibrary.dll.config" and then deployed in the library's location. The settings file should have similar content to this:

<?xml version="1.0"?>
<configuration>
  <configSections>
    <sectionGroup name="applicationSettings" type="System.Configuration.ApplicationSettingsGroup, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
      <section name="Your.NameSpace.Properties.Settings" type="System.Configuration.ClientSettingsSection, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false"/>
    </sectionGroup>
  </configSections>
  <applicationSettings>
    <Your.NameSpace.Properties.Settings>
      <setting name="YourLibrary_WebReferences_YourWebService" serializeAs="String">
        <value>http://localhost:3861/YourWebService.asmx</value>
      </setting>
      <setting name="AnotherSetting" serializeAs="String">
        <value>False</value>
      </setting>
    </Your.NameSpace.Properties.Settings>
  </applicationSettings>
  <startup>
    <supportedRuntime version="v2.0.50727"/>
  </startup>
</configuration>

I haven't needed to read connection strings from the config file, but that should be possible by changing the name of the section group that you get after opening the exe configuration.

The reason why I needed to do this is that I have a User Control which wraps a ActiveX/COM library which is then hosted in IE in an "object" tag. I have got the use of "param" tags working, so I could have used that mechanism to have passed the settings into the User Control, but this method seemed a logical choice at the time. Plus I wasn't going to let this particular problem beat me!

HTH pridmorej :)

Answer 3

This kind of configuration issue is solved quite nicely using Enterprise Library "Shared Configuration Sources" and "Differential Configurations" (for easily switching between multiple environments, etc.).

To learn about Advanced Configuration Scenarios, try starting here:

http://msdn.microsoft.com/en-us/library/ff664552(v=pandp.50).aspx

And to integrate the Enterprise Library Configuration Tool (GUI) in Visual Studio, try here:

http://visualstudiogallery.msdn.microsoft.com/029292f0-6e66-424f-8381-3454c8222f9a

The learning curve may seem a bit overwhelming at first, but it is well worth the effort, especially if you are dealing with complex enterprise ecosystems. The integrated tool actually makes it pretty easy to set up a very sophisticated configuration system, and manage it as your requirements change.

BTW: Once you get the hang of it, you'll probably end up wanting to use it for a lot more than just your Connection Strings!

Answer 4

The ConfigurationManager.OpenExeConfiguration didn't work for me.

But, Properties.Settings.Default.<SettingName> worked well.

Answer 5

Would it be an option to reference the library's configuration file from each web service's configuration? There is an XML include-like mechanism in .NET:

Use XML includes or config references in app.config to include other config files' settings

http://blog.andreloker.de/post/2008/06/Keep-your-config-clean-with-external-config-files.aspx

While you'd still need to edit each web.config, the actual content is maintained in a single place.

Answer 6

You can use the opensource Config.Net library which supports multiple sources of data, including your one https://github.com/aloneguid/config

Answer 7

You can read the configuration settings of the class library from the hosting application's web.config or app.config.

If the class library is referenced in a console application, put the settings, the class library needs, in the app.config of the console application (say under appSettings) and read it from the class library using ConfigurationManager under System.Configuration.

If the class library is referenced in a web application, put the settings the class library needs in the web.config of the web application (say under appSettings) and read it from the class library using ConfigurationManager under System.Configuration.