Replacing XML element in Python

Question

I am trying to replace the element inside of bbox with a new set of coordinates.

my code :

    # import element tree
    import xml.etree.ElementTree as ET 


    #import xml file
    tree = ET.parse('C:/highway.xml')
    root = tree.getroot()

    #replace bounding box with new coordinates

    elem = tree.findall('bbox')
    elem.txt = '40.5,41.5,-12.0,-1.2'

my xml file:

   <geoEtl>
    <source>
        <server>localhost</server>
        <port>xxxx</port>
        <db>vxxx</db>
        <user>xxxx</user>
        <passwd>xxxx</passwd>
    </source>
    <targetDir>/home/firstuser/</targetDir>
    <bbox>-52.50,-1.9,52.45,-1.85</bbox>
    <extractions>
        <extraction>
            <table>geo_db_roads</table>
            <outputName>highways</outputName>
            <filter>highway = 'motorway'</filter>
            <geometry>way</geometry>
            <fields>
                <field>name</field>             
            </fields>
        </extraction>
    </extractions>
   </geoEtl>

have tried a variety of ways to do of things i found here but it doesnt seem to be working. thanks.

The error I'm receiving is as follows:

line 20, in <module> elem.txt = '40.5,41.5,-12.0,-1.2' AttributeError: 'list' object has no attribute 'txt' –

line 20, in <module> elem.txt = '40.5,41.5,-12.0,-1.2' AttributeError: 'list' object has no attribute 'txt' — Moggy
– Moggy, Commented Jul 2, 2013 at 22:55

abarnert · Accepted Answer · 2013-07-02 22:55:53Z

9

The findall function, as the name implies, finds all matching elements, not just one.

So, after this:

elem = tree.findall('bbox')

elem is a list of Elements. And, as with any other list, this:

elem.txt = '40.5,41.5,-12.0,-1.2'

Is going to give you an error:

AttributeError: 'list' object has no attribute 'txt'

If you want to do something to every member of a list, you have to loop over it:

elems = tree.findall('bbox')
for elem in elems:
    elem.txt = '40.5,41.5,-12.0,-1.2'

answered Jul 2, 2013 at 22:55

abarnert

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2 Comments

Moggy Over a year ago

ok awesome it runs no problem now, should be it rewriting the new coordinates on my XML file or is that a different issue?

abarnert Over a year ago

@Moggy: ET.parse('C:/highway.xml') just parses the file into a tree in memory. If you want to modify the XML file, you have to edit the tree, then _save it back to a file_. You can do tree.write('C:/highway.xml')` if you want to overwrite the original version with the new one.

John · Accepted Answer · 2013-07-02 23:15:05Z

3

If your file isn't update it is most likely because you are not saving it, you can use the tree.write method to do just that.

tree.write('output.xml')

answered Jul 2, 2013 at 23:15

John

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Comments

Taras · Accepted Answer · 2016-12-12 14:25:55Z

1

# import element tree
import xml.etree.ElementTree as ET 

#import xml file
tree = ET.parse('C:/highway.xml')
root = tree.getroot()

elems = root.findall(".//bbox")

for elem in elems:
    elem.text = '40.5,41.5,-12.0,-1.2'

tree.write('C:/highway.xml')

answered Dec 12, 2016 at 14:25

Taras

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Comments

kamjagin · Accepted Answer · 2013-07-02 22:56:05Z

0

If you want to replace the text of all boundingboxes with '40.5,41.5,-12.0,-1.2', try this

bboxes = tree.xpath('//bbox')
for bbox in bboxes:
    bbox.text= '40.5,41.5,-12.0,-1.2'

answered Jul 2, 2013 at 22:56

kamjagin

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3 Comments

Moggy Over a year ago

i get AttributeError: 'ElementTree' object has no attribute 'xpath'

kamjagin Over a year ago

Yes - sorry. I also had slightly simpler code for parsing - I used etree as my base class and etree includes the xpath function. I had assumed that ElementTree has that too but I never double-checked it

abarnert Over a year ago

@kamjagin: There is no class called etree anywhere. In both the 2.x and 3.x stdlibs, etree is a package with nothing in it but the ElementTree module; in the separately-installable module from Fredrick Lundh's website, nothing at all has that name; in lxml, etree is a module with roughly the same API as ElementTree in the others. Element handles XPath syntax in the findall method; in the lxml implementation you can also call it as xpath, but you still call it on Elements, not an empty package that you've somehow used as a base class.

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