Custom Configuration Sections (app.config/web.config)

[balabaster]

Okay, I decided that I needed to understand the whole custom configuration file bits and so I've spent some time playing around with it. It seems (in the most) relatively straight forward. However, I've come unstuck with one scenario that I'm trying to figure out the code for:

Consider the following configuration:

[HTML]<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
<section name="DummySection" type="ConsoleApplication1.DummySection, ConsoleApplication1" />
</configSections>
<DummySection>
<DummyElement name="1" description="first element">
<ElementData name="1.1" attr1="1.1.1" attr2="1.1.2" />
<ElementData name="1.2" attr1="1.2.1" attr2="1.2.2" />
<ElementData name="1.3" attr1="1.3.1" attr2="1.3.2" />
<ElementData name="1.4" attr1="1.4.1" attr2="1.4.2" />
</DummyElement>
<DummyElement name="2" description="second element">
<ElementData name="2.1" attr1="2.1.1" attr2="2.1.2" />
<ElementData name="2.2" attr1="2.2.1" attr2="2.2.2" />
<ElementData name="2.3" attr1="2.3.1" attr2="2.3.2" />
<ElementData name="2.4" attr1="2.4.1" attr2="2.4.2" />
</DummyElement>
<DummyElement name="3" description="third element">
<ElementData name="3.1" attr1="3.1.1" attr2="3.1.2" />
<ElementData name="3.2" attr1="3.2.1" attr2="3.2.2" />
<ElementData name="3.3" attr1="3.3.1" attr2="3.3.2" />
<ElementData name="3.4" attr1="3.4.1" attr2="3.4.2" />
</DummyElement>
</DummySection>
</configuration>[/HTML]

Perfect, I have a sample configuration file that can be used to configure my application, so now I've gotta create the classes that read it...

The code is kind of long winded...

I've got (for brevity I've cut the code down to just the bare bones):

Public Class ConfigClass : ConfigurationSection{
  [ConfigurationCollection(GetType(DummyElementCollection), AddItemName:="DummyElement"]
  DummyElement Elements{
    get { return (DummyElementCollection)mybase("DummyElement"); }
}
 
//Collections
Public Class DummyCollection : ConfigurationElementCollection{
  //Cut out code
}
 
Public Class ElementDataCollection : ConfigurationElementCollection{
}
 
//Configuration elements
Public Class DummyElement : ConfigurationElement{
}
 
Public Class ElementData : ConfigurationElement{
}

Now, given that I have elements that are also collections, how do I account for this in my code? I've read many examples of custom sections using the standard syntax, i.e.:

[HTML]<MySection>
<MyCollectionA>
<add key="A1" value="blahA1" />
<add key="A2" value="blahA2" />
</MyCollectionA>
<MyCollectionB>
<add key="B1" value="blahB1" />
<add key="B2" value="blahB2" />
</MyCollectionB>
</MySection>[/HTML]

I can make all these work just fine... I know about the

[ConfigurationElementCollection(GetType(DummyElemen tCollection)AddItemName:="DummyElement"]

and
[ConfigurationElementCollection(GetType(ElementData Collection), AddItemName:="ElementData"]

but where do I put these? Ahead of my class declarations for my collections or on the property where the collection is referenced? In both spots I get errors that one parameter or another is missing.

What happens when you have elements that have attributes and are also collections? The major difference I see between the config file I want to use and the standard one is that I'd like to have attributes in elements that are also headers for collections.

If I have attributes in the collection header, my code bombs telling me that there are unrecognized attributes.

Can anyone point me in the direction of decent documentation for this type of thing?

[int08h]

You are very close to the solution, however it is not a very good practice in XML structure, because XML is a string semantic language, collection element should be presented in a collection wrap, my suggestion is:

<DummyElement name="1" description="first element">
  <ElementData>
    <ElementData name="1.1" attr1="1.1.1" attr2="1.1.2" />
    <ElementData name="1.2" attr1="1.2.1" attr2="1.2.2" />
    <ElementData name="1.3" attr1="1.3.1" attr2="1.3.2" />
    <ElementData name="1.4" attr1="1.4.1" attr2="1.4.2" />
  </ElementData>
</DummyElement>

For your ElementData, you must implement a collection which inherits from ConfigurationElementCollection, let's call it ElementDataCollection

Then you should make a property of ElementDataCollection in your DummyElement class and apply below attribute to it

[ConfigurationProperty("ElementData")]
[ConfigurationCollection(typeof(ElementDataCollection), AddItemName = "ElementData")]

[balabaster]

You are very close to the solution, however it is not a very good practice in XML structure, because XML is a string semantic language, collection element should be presented in a collection wrap, my suggestion is:

<DummyElement name="1" description="first element">
<ElementData>
<ElementData name="1.1" attr1="1.1.1" attr2="1.1.2" />
<ElementData name="1.2" attr1="1.2.1" attr2="1.2.2" />
<ElementData name="1.3" attr1="1.3.1" attr2="1.3.2" />
<ElementData name="1.4" attr1="1.4.1" attr2="1.4.2" />
</ElementData>
</DummyElement>

For your ElementData, you must implement a collection which inherits from ConfigurationElementCollection, let's call it ElementDataCollection

Then you should make a property of ElementDataCollection in your DummyElement class and apply below attribute to it

[ConfigurationProperty("ElementData")]
[ConfigurationCollection(typeof(ElementDataCollection), AddItemName = "ElementData")]

Yeah, I got an example working like that on Friday...and while I agree, syntactically it may be more um..."correct", it requires two extra classes that I personally think are unnecessary. I am currently using the "correct" method and was wondering how exactly I'd go about condensing my code.

[balabaster]

After having spent quite a few hours trawling for information regarding this subject and quite a few more deciphering it to figure out how to apply more complex configuration scenarios, I decided that the information available is poor at best. So I put together a demonstration solution for custom configuration and how to work with it.

I hope this is of help to people using custom configuration. If anyone can point out errors, omissions and areas for improvement, please yell.

[balabaster]

I've also written a document to go with the demonstration code, to assist with interpretation...