Moving a custom configuration group to a separate file

Question

I've recently wrote a rather large custom configuration group. I'm curious if it is possible to move this configuration to a separate file via the following:

<configuration>
    <configSections>
        <sectionGroup name="MyCustomGroup">
            <section name="MyCustomSection"/>
        </sectionGroup>
    </configSections>
    <MyCustomGroup file="alt.config" />
</configuration>

This is something similar to what you can do with the file attribute for appSettings. I realize there is most likely a need to create a ConfigurationPropertyAttribute for my custom section handler, however I've been unsuccessful in finding any example or direction in this regard.

Answer 1

As far as I know, you cannot externalize an entire SectionGroup (i.e. MyCustomGroup) using the configSource attribute, but you have to handle this on the Section level (i.e. MyCustomSection)

<configuration>
    <configSections>
        <sectionGroup name="MyCustomGroup">
                <section name="MyCustomSection"/>
        </sectionGroup>
    </configSections>
    <MyCustomGroup>    
       <MyCustomSection configSource="externalfile.config" />
    </MyCustomGroup>
</configuration>

The external file externalfile.config would then contain your actual config settings, starting directly with your own custom section tag (no leading <?xml....?> or <configuration> or anything needed):

<MyCustomSection>
    ... your settings here......
</MyCustomSection>

Marc