Merging two XMLs with retaining attribute-value from base-xml - shell

Question

I have two XMLs which look like below. How to merge 2 of them with scripting to take values from new.xml & retainging non-existing attribute-value form base.xml
base.xml:
<element name="ind"
dbs="name1, name2, name4"
server="ServerName"
good-attribute="234"/>
My new.xml looks like this:
<element name="ind"
description="My desc"
dbId="someId"
moreAttr="someVal"
dbs="name1, name2, name4, name12, name3"
server="ServerName" />
I would like to take latest dbs value from new.xml to merge.xml and with retaining good-attribute value present only in base.xml:
merge.xml:
<element name="ind"
description="My desc"
dbId="someId"
moreAttr="someVal"
dbs="name1, name2, name4, name12, name3"
server="ServerName"
good-attribute="234" />
With paste just paste fieldwise and vimdiff shows diff, but does not allow to select. Any inbuild support is there or need it to be implemented with replacements with sed + awk?

Answer 1

Here's a direct implementation in Python:
#!/usr/bin/env python
# Python 2.5+ compatible
import sys
import xml.etree.ElementTree as etree
def main():
output_file = getattr(sys.stdout, 'buffer', sys.stdout)
dict2xml(merge_dicts(*map(xml2dict, sys.argv[1:])), output_file)
def xml2dict(source):
return dict((el.get('name'), el.attrib)
for el in etree.parse(source).getiterator('element'))
def merge_dicts(base, new):
merged = {}
# for each element from new xml
for name, attr in new.items():
# combine attributes from base and new xmls preferring new values
d = merged[name] = base.get(name, {})
d.update(attr)
return merged
def dict2xml(d, sink):
root = etree.Element('root')
for name, attr in d.items():
etree.SubElement(root, 'element', attr)
etree.ElementTree(root).write(sink, encoding='utf-8')
main()
Save this code to merge-xml file and run chmod +x merge-xml. Then:
$ ./merge-xml base.xml new.xml >merge.xml
Here's Python 2.4+ compatible version:
#!/usr/bin/env python
import sys
from xml.dom import minidom
def main():
output_file = getattr(sys.stdout, 'buffer', sys.stdout)
dict2xml(merge_dicts(*map(xml2dict, sys.argv[1:])), output_file)
def xml2dict(source):
doc = minidom.parse(source)
return dict((el.getAttribute('name'), attr2dict(el.attributes))
for el in doc.getElementsByTagName('element'))
def attr2dict(nodemap):
d = {}
for i in range(nodemap.length):
attr = nodemap.item(i)
d[attr.name] = attr.value
return d
def merge_dicts(base, new):
merged = {}
# for each element from new xml
for name, attr in new.items():
# combine attributes from base and new xmls preferring new values
d = merged[name] = base.get(name, {})
d.update(attr)
return merged
def dict2xml(d, sink):
doc = minidom.getDOMImplementation().createDocument(None, "root", None)
root = doc.documentElement
for name, attr in d.items():
el = doc.createElement('element')
for name, value in attr.items():
el.setAttribute(name, value)
root.appendChild(el)
sink.write(doc.toprettyxml(encoding='utf-8'))
main()