How do you create webpart-specific config files?

Question

How do you create application specific config files for a GAC-deployed webpart in SharePoint 2010?

1. Which one or more of app.config/web.config/supplemental config are appropriate to use for webparts?

2. Where is the best place for the app.config/web.config file to be placed? According to
   http://msdn.microsoft.com/en-us/library/ms460914.aspx
   it should be placed in
   "\Program Files\Common Files\Microsoft Shared\Web Server Extensions\wpresources",
   but it also mentions

   The web.config files in the \wpresources folders should not be modified. The settings of these files disallow pages or items that can be compiled. If these settings are changed, the security state for the compiled code differs greatly from the security state for code that runs from the Local_Drive:\Inetpub\wwwroot directory.

3. Can this be done in Visual Studio through including the .config file within the wsp file?

4. Can this be deployed in one place for a farm, or does it need to be deployed to each server?

From reading the above link, I am thinking that the answers to 1 and 2 are to create a supplemental config in
"\Program Files\Common Files\Microsoft Shared\Web Server Extensions\wpresources" Is this correct?

Answer 1

Microsoft's patterns & practices group has published guidance for SharePoint 2010, including an heirarchical configuration storage provider as part of "The Application Setting Manager."

Recommended.

Answer 2

I assume you need this because you want to control webpart properties from a central location. Below are the options you can consider :

1. Use <appsettings> in web.config and read them using ConfigurationManager.AppSettings in webpart.This will allow you to store settings at the scope of web application.

2. Use a list at Root site or subsites depending on how global you want to store them.The list columns will act as key and the item as values. You will have just one Row in this list. Your webpart will read the list programmatically. One benefit of this approach is You can create versions, in case you want to restore this webpart to previous settings.

3. For farm level properties, you can use a xml file at */_layouts* folder and consume it in webpart.If you want you can cache it as well.
4. Hierarchical object store and Property bags.

Answer 3

SharePoint web parts have own settings mechanism base on marking properties with attributes -an example can be found here - http://nishantrana.wordpress.com/2009/01/01/writing-custom-properties-for-web-parts-in-sharepoint/ and http://www.wictorwilen.se/Post/Web-Part-Properties-part-1-introduction.aspx. For more advanced requests you can see EditorPart http://www.wictorwilen.se/Post/Web-Part-Properties-part-2-Editor-Parts.aspx. Also there is a very good book from @Wictor - SharePoint MVP - WebParts in Action - http://www.manning.com/wilen/

Generally, it's not a good way to customize web config, cause it's affects the whole sharepoint web application and require restarting app. But if it's really required - http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.administration.spwebconfigmodification.aspx to make changes to web.config

If your setting can be viewed by users - you can just create an xml document and deploy it to _layouts folder, when webpart is rendered, it can get data from there.

Also you can deploy configuration xml to feature folder, and get configuration data from there.