How to create nested dictionary from XML using python?

Question

I am reading an XML file and take part of it and write it to YAML file. For example, in this xml file,

<project>


  <scm class="hudson.scm.NullSCM"/>
  <assignedNode>python</assignedNode>
  <canRoam>false</canRoam>
  <disabled>false</disabled>
  <blockBuildWhenDownstreamBuilding>false</blockBuildWhenDownstreamBuilding>
  <blockBuildWhenUpstreamBuilding>false</blockBuildWhenUpstreamBuilding>
  <triggers>
    <hudson.triggers.TimerTrigger>
      <spec>H * * * *</spec>
    </hudson.triggers.TimerTrigger>
  </triggers>
  <concurrentBuild>false</concurrentBuild>
  <builders>

I want to read only the disabled value and the spec value and write it to a YAML file like this: Expected output:

disabled: 'false'
name: Cancellation_CMT_Tickets
triggers:
  hudson.triggers.TimerTrigger:
    spec: H * * * *

Only when my resultant dictionary is in this format

d = {"trigger":{"hudson.triggers.TimerTrigger": {"spec": "H * * * *"}}}

I can dump that into yaml file with the above format. MY current code looks like this, search key is passed as runtime arguments

import os, xml.etree.ElementTree as ET
import yaml,sys
tree = ET.parse('test.xml')
root = tree.getroot()

d = {}
def xmpparse(root,searchkey):
    for child in root:
        if child.tag == searchkey:
            d[child.tag]=child.text
        elif len(child):
           xmpparse(child,searchkey)
for i in sys.argv:
    xmpparse(root,i)

print(yaml.dump(d, default_flow_style=False))

Current output:

disabled: 'false'
spec: H * * * *

Any help would be much appreciated. Thanks in advance!

Don't know much (or anything...) about YAML, but I can get your dictionary to its proper format (using the lxml library), if that helps. — Jack Fleeting
– Jack Fleeting, Commented Jul 20, 2019 at 19:11
I want to have a nested dictionary for only the entries I need to grab from the XML. Can you help me with that? While doing the recursive operation, it should start putting the values in nested dictionary — Jayabalan Bala
– Jayabalan Bala, Commented Jul 20, 2019 at 20:39

Jack Fleeting · Accepted Answer · 2019-07-20 21:01:12Z

1

I believe this should take care of the nested dictionary problem, at least; it's based on various answers on SO on how to form nested dictionaries (and there may be other methods):

    import lxml.html as LH

    class NestedDict(dict):
        def __missing__(self, key):
              self[key] = NestedDict()
              return self[key]

    data =     [your xml above]

    doc = LH.fromstring(data)

    for i in doc:
           if i.tag == 'triggers':
                for child in i.getchildren():
                    d = NestedDict()
                    d[i.tag][child.tag][child[0].tag] = i.text_content().strip()

    print(d)

Output:

{'triggers': {'hudson.triggers.timertrigger': {'spec': 'H * * * *'}}}

answered Jul 20, 2019 at 21:01

Jack Fleeting

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1 Comment

Jayabalan Bala Over a year ago

I forgot to mention something, my code should work in such a way that, it can go any depth for the searchKey passed as runtime arguments. It looks like your solution can just work for this XML file. I didn't try that yet though. But d[i.tag][child.tag][child[0].tag] here you are just making entry with 3 keys

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