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From Maruan Sahyoun <sahy...@fileaffairs.de>
Subject Re: Fetching options for PDChoice causes ClassCastException
Date Sat, 07 Apr 2018 13:26:18 GMT
Hi,

> Am 07.04.2018 um 15:01 schrieb Matthias Gall <matthias.gall@trimplement.com>:
> 
> Dear all,
> 
> I am trying to fetch the options available for a PDChoice field in a form but get a ClassCastException
from the PDFBox internals.
> 
> The problematic PDF is an Inheritance Tax form from the UK's Revenue and Customs, specifically
I am currently looking at IHT405:
> 
> 	https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/697346/IHT405_online.pdf
> 
> I use this code to iterate over the fields:
> 
> 	PDDocument doc = PDDocument.load(resource.getFile());
> 	PDDocumentCatalog catalog = doc.getDocumentCatalog();
> 	PDAcroForm form = catalog.getAcroForm();
> 	for (PDField field : form.getFields()) {
> 		if ("Ch".equals(field.getFieldType())) {
> 			PDChoice choice = (PDChoice) field;
> 			// All these variants fail with a ClassCastException:
> 			choice.getOptions();
> 			choice.getOptionsDisplayValues();
> 			choice.getOptionsExportValues(); // internally just delegates to getOptions()
> 		}
> 	}
> 
> This is a stacktrace for e.g. the getOptionsExportValues() call:
> 
> 	java.lang.ClassCastException: org.apache.pdfbox.cos.COSArray cannot be cast to org.apache.pdfbox.cos.COSString
> 		at org.apache.pdfbox.pdmodel.common.COSArrayList.convertCOSStringCOSArrayToList(COSArrayList.java:367)
> 		at org.apache.pdfbox.pdmodel.interactive.form.FieldUtils.getPairableItems(FieldUtils.java:182)
> 		at org.apache.pdfbox.pdmodel.interactive.form.PDChoice.getOptions(PDChoice.java:91)
> 		at org.apache.pdfbox.pdmodel.interactive.form.PDChoice.getOptionsExportValues(PDChoice.java:210)
> 
> The problem is that the expected "stringArray" also contains COSArrays with value and
label for the options:
> 
> 	COSArray{[COSString{ }, COSArray{[COSString{Mr}, COSString{MR}]}, COSArray{[COSString{Mrs},
COSString{MRS}]}, COSArray{[COSString{Miss}, COSString{MISS}]}, COSArray{[COSString{Ms}, COSString{MS}]}]}
> 

this is a limitation in the current implementation which expects either an array fo strings
or an array of arrays/pairs but not a mix. 


> This does not seem to be expected in FieldUtils.getPairableItems, which introspects only
the first item of the array and thus treats the array as an array of strings.
> 
> I found the bug with PDFBox 2.0.4 and upgraded to 2.0.9 which didn't help.
> 
> Following the advised practices for bug reports I raise this on the mailing list first.
I appreciate your feedback on how to proceed.

I've opened PDFBOX-4185 for that. Feel free to comment there and add yourself as a watcher.

BR
Maruan

> 
> Kind regards
> Matt
> 
> 
> 
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