trying to add element to xmeml format XML with xml.etree.ElementTree

Question

There's an XML file generated video editing software, which contains all the data for clip exhange. The XML is valid for the software. The only thing it lacks is an element for fielddominance (I need to set 'upper' value there) The hard part for me that the file structure. Here's like this looks like:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE xmeml>
<xmeml version="5">
<sequence>
<name>to_color (Resolve)</name>
<duration>121597</duration>
<rate>
    <!-- ... -->
</rate>
<in>-1</in>
<out>-1</out>
<timecode>
    <!-- ... -->
</timecode>
<media>
    <video>
        <track>
            <clipitem id="983_0121_01_1_5FF70094C4A64669BC77.mov 0">
                <name>983_0121_01_1_5FF70094C4A64669BC77.mov</name>
                <duration>271</duration>
                <rate>
                    <timebase>25</timebase>
                    <ntsc>false</ntsc>
                </rate>
                <start>0</start>
                <end>221</end>
                <enabled>true</enabled>
                <in>25</in>
                <out>246</out>
                <file id="983_0121_01_1_5FF70094C4A64669BC77.mov 2">
                    <duration>271</duration>
                    <rate>
                        <!-- ... -->
                    </rate>
                    <name>983_0121_01_1_5FF70094C4A64669BC77.mov</name>
                    <pathurl>file://Capture2/Capture2/SHARED/DAVINCI_Render/111.mxf</pathurl>
                    <timecode>
                        <!-- ... -->
                    </timecode>
                    <media>
                        <video>
                            <duration>271</duration>
                            <samplecharacteristics>
                                <width>1920</width>
                                <height>1080</height>
                            </samplecharacteristics>
                        </video>
                    </media>
                </file>
                <compositemode>normal</compositemode>
                <filter>
                    <enabled>true</enabled>
                    <start>0</start>
                    <end>271</end>
                    <effect>
                        <name>Opacity</name>
                        <effectid>opacity</effectid>
                        <effecttype>motion</effecttype>
                        <mediatype>video</mediatype>
                        <effectcategory>motion</effectcategory>
                        <parameter>
                            <name>opacity</name>
                            <parameterid>opacity</parameterid>
                            <value>100</value>
                            <valuemin>0</valuemin>
                            <valuemax>100</valuemax>
                        </parameter>
                    </effect>
                </filter>
            </clipitem>
        </track>
        <format>
            <samplecharacteristics>
                <!-- this is what I need to add START -->
                <fielddominance>upper</fielddominance> 
                <!-- this is what I need to add END-->
                <width>1920</width>
                <height>1080</height>
                <pixelaspectratio>square</pixelaspectratio>
                <rate>
                    <!-- ... -->
                </rate>
                <codec>
                    <!-- ... -->
                </codec>
            </samplecharacteristics>
        </format>
    </video>
    <audio>
        <track>
            <!-- ... -->
        </track>
    </audio>
</media>
</sequence>
</xmeml>

The element I need to add is in sequence - media - video - format - samplecharacteristics field. But this tag also exists in sequence - media - video - track - clipitem - file - media - video - samplecharacteristics

I use xml.etree.ElementTree as a parser. Here's what I am trying, and of course I'm doing it all wrong:

import xml.etree.ElementTree as ET
tree = ET.parse(r'\\capture2\11\in.xml')
root = tree.getroot()
fieldd = ET.Element('fielddominance')
fieldd.set('field','upper')
for tag in root.iter('samplecharacteristics'):
    tag.append(fieldd)
output_file  = r'\\capture2\11\new.xml'
with open(output_file, 'wb') as out:
    tree.write(out, encoding='utf-8')

This adds fielddominance to every samplecharacteristics tag. And I have no idea how to set 'upper' value inside tag, not as attribute.

What I would like is to write <fielddominance>upper</fielddominance> only to format tag, but omit <track> tags

Answer 1

You can use ElementTree's limited XPath support to isolate the samplecharacteristics you want to modify. Also, setting the text of an element is done simply by setting its .text attribute.

Try this:

import xml.etree.ElementTree as ET

tree = ET.parse('in.xml')
fieldd = ET.Element('fielddominance')
fieldd.text = 'upper'
for tag in tree.findall("./sequence/media/video/format/samplecharacteristics"):
    tag.append(fieldd)
tree.write('new.xml', "UTF-8", True)