Question

I have a config file that is used in several projects, general.config, looks like:

<?xml version="1.0" encoding="utf-8" ?>
<appSettings>
   <add key="mykey1" value="myvalue1"/>    
   <add key="mykey2" value="myvalue2"/>
</appSettings>

In one of the projects, I need to override one of the two settings. So the app.config of this project looks like:

<?xml version="1.0"?>
<configuration>
  <appSettings file="general.config">
    <remove key="mykey1"/>
    <add key="mykey1" value="anothervalue"/>
    <add key="mykey3" value="myvalue3"/>
  </appSettings>  
</configuration>

But remove is not working here. How can I override mykey1 without breaking mykey2? add works in this case. I can get myvalue3 from ConfigurationManager.

EDIT: general.config is copied to output folder automatically when compiling. Don’t worry about the path issue. Currently I got:

ConfigurationManager.AppSettings["mykey1"] 
     //I got "myvalue1", but I want "anothervalue" here
     //that is, this item is "overrided", just like virtual methods in C#
ConfigurationManager.AppSettings["mykey2"] 
     //this setting will not be modified, currently it works fine
ConfigurationManager.AppSettings["mykey3"]   //good 

Answer 1

MSDN helps to answer the question:

You can use the file attribute to
specify a configuration file that
provides additional settings or
overrides the settings that are
specified in the appSettings element.
You can use the file attribute in
source control team development
scenarios, such as when a user wants
to override the project settings that
are specified in an application
configuration file. Configuration
files that are specified in a file
attribute must have the appSettings
element rather than configuration
element as the root node.

So, the settings in your general.config will override items in app.config. This is the opposite of what you want (to have app.config items override general.config items). You will have to resolve this issue in C# code (it will inevitably look ugly).