How do I ignore an entire tag?

[ravenfeld]

Hello, I'm trying to make a GPX file parser but I'm getting stuck because some sites send this style of tag.
At the moment I don't need the information in the extension but it is still read and so the mtb:scale line crashes.

Is it possible for the line to ignore the inside of a tag?

  <trkpt lat="45.148454" lon="5.888473">
       <ele>1205.75</ele>
       <extensions>
         <gpxtpx:TrackPointExtension>
           <gpxtpx:Extensions>
             <reversedirection>yes</reversedirection>
             <highway>path</highway>
             <mtb:scale>2</mtb:scale>
           </gpxtpx:Extensions>
         </gpxtpx:TrackPointExtension>
       </extensions>
     </trkpt>

[ravenfeld]

Perhaps the easiest thing to do is to enter the isNamespaceAware parameters?

private constructor() : this(XmlPullParserFactory.newInstance().apply { isNamespaceAware = true }.newPullParser())

[pdvrieze]

So you mean that you have one file format with path trkpt/extensions/gpxtpx:TrackPointExtension/mtb:scale and one with trkpt/gpxtpx:TrackPointExtension/mtb:scale. Those are different (maybe compatible) file/xml formats. There are some directions you could go into:

• Pre-filter the format to elude unneeded outer tags
• Have a serial delegate class that captures either option and then coalesces the results when transformed to your final version
• Create a custom serializer that encapsulates the differences, possibly using filtering.
• H

[ravenfeld]

I want to parse GPX files, but I don't know who exported the files and depending on the site there is data added in the extension.
I don't want to read them, but this could cause a crash.

[pdvrieze]

@ravenfeld You can configure your policy to handle unknown tags/attributes (either by mapping them to a field, ignore them, log them, or throw an exception). That should deal with crashes. Alternatively it is possible to have @XmlValue List<Element> and XmlOtherAttributes to capture the unknown children in a generic way (rather than ignoring them). You can also use either Element or CompactFragment as type of an "extension" child and that will just contain the content of that tag without caring about the specifics.

What neither option does is give you access to data inside the extension in a typesafe way.

[rickytribbia]

Hello @pdvrieze can I ask how is possible to customize the policy to ignore unknown fields, log them or throw an exception?

Thank you

[rickytribbia]

Found it!

val xml = XML {
        defaultPolicy {
            unknownChildHandler = XmlConfig.IGNORING_UNKNOWN_CHILD_HANDLER
        }
    }

or

val xml = XML {
        defaultPolicy {
                unknownChildHandler = UnknownChildHandler { input, inputKind, descriptor, name, candidates -> 
                   ...
                }
        }
    }

[pdvrieze]

val xml = XML {
        defaultPolicy {
                unknownChildHandler = UnknownChildHandler { input, inputKind, descriptor, name, candidates -> 
                   ...
                }
        }
    }

With this one you can even handle renames (or incorrect namespaces).