Add offset to all XML attributes

Question

I've an XML-File

<?xml version="1.0" encoding="ISO-8859-1" standalone="yes"?>
<PageDescription>
    <Page>
        <Row />
        <Row>
            <Cell cellRow="0" cellColumn="0" Pos="693" />           
            <Cell cellRow="0" cellColumn="1" Pos="2693" />
        </Row>
    </Page>
</PageDescription>  

, which contains different structures and attributes. Now I want to change the value of for example the attribute Pos by adding a certain offset, in this case 12. But I got an error.

for currfile in allfiles:

    filepathstr = xmldir + "/" + currfile;    
    tree = xee.ElementTree(file=filepathstr)

    for tag in tree.findall('Page'):
        for tag2 in tag.findall('Row'):
            for tag3 in tag2.findall('Cell'):                              

                selectTag = tag3.attrib['Pos']
                newVal = int(selectTag)+12
                tag3.set('Pos', newVal)

expfilename = expdir + "/" + currfile

tree.write(expfilename,encoding="ISO-8859-1")

I get the following error

     <class 'xml.etree.ElementTree.ElementTree'>
    ---------------------------------------------------------------------------
    TypeError                                 
    Traceback (most recent call last)

C:\ProgramData\Anaconda3\lib\xml\etree\ElementTree.py in _escape_attrib(text)
   1079     try:
-> 1080         if "&" in text:
   1081             text = text.replace("&", "&amp;")

TypeError: argument of type 'int' is not iterable

During handling of the above exception, another exception occurred:

TypeError                                 Traceback (most recent call last)
<ipython-input-2-b1ffea99d1f3> in <module>()
 67     expfilename = expdir + "/" + currfile
 68 
---> 69     tree.write(expfilename,encoding="ISO-8859-1")

Does anyone see the error? Or are such tasks easier with XPath?

Answer 1

In ElementTree, attribute values must be strings explicitly, there is no automatic type conversion.

If you want to store something else, like an int , you must do the conversion to string yourself. After all, when you read the attribute value, you got a string and did the conversion to int yourself as well.

Using XPath will remove the need for nested loops.

for currfile in allfiles:
    tree = xee.ElementTree(os.path.join(xmldir, currfile))

    for cell in tree.findall('./Page/Row/Cell'):
        pos = int(cell.get('Pos'))
        cell.set('Pos', str(pos + 12))

    tree.write(os.path.join(expdir, currfile))

Also, unless there is a good reason, don't store XML files in legacy encondings like ISO-8859-1. Use Unicode encodings, like UTF-8.