Write xml from list of path/values

问题

This is a follow-up to the previous question: Write xml with a path and value. I want to now add in two additional things: 1) Attributes and 2) Multiple items with a parent node. Here is the list of paths I have:

[
  {'Path': 'Item/Info/Name', 'Value': 'Body HD'},
  {'Path': 'Item/Info/Synopsis', 'Value': 'A great movie'},
  {'Path': 'Item/Locales/Locale[@Country="US"][@Language="ES"]/Name', 'Value': 'El Grecco'},      
  {'Path': 'Item/Genres/Genre', 'Value': 'Action'},
  {'Path': 'Item/Genres/Genre', 'Value': 'Drama'},
  {'Path': 'Item/Purchases/Purchase[@Country="US"]/HDPrice', 'Value': '10.99'},
  {'Path': 'Item/Purchases/Purchase[@Country="US"]/SDPrice', 'Value': '9.99'},
  {'Path': 'Item/Purchases/Purchase[@Country="CA"]/SDPrice', 'Value': '4.99'},
]

The xml it should generate is:

<Item>
    <Info>
        <Name>Body HD</Name>
        <Synopsis>A great movie</Synopsis>
    </Info>
    <Locales>
        <Locale Country="US" Language="ES">
            <Name>El Grecco</Name>
        </Locale>
    </Locales>
    <Genres>
        <Genre>Action</Genre>
        <Genre>Drama</Genre>
    </Genres>
    <Purchases>
        <Purchase Country="US">
            <HDPrice>10.99</HDPrice>
            <SDPrice>9.99</SDPrice>
        </Purchase>
        <Purchase Country="CA">
            <SDPrice>4.99</SDPrice>
        </Purchase>
    </Purchases>
</Item>

How would I build this out?

回答1:

To build a XML tree from xpaths and values, I use RegEx and lxml:

import re

from lxml import etree

The entries are:

entries = [
    {'Path': 'Item/Info/Name', 'Value': 'Body HD'},
    {'Path': 'Item/Info/Synopsis', 'Value': 'A great movie'},
    {'Path': 'Item/Locales/Locale[@Country="US"][@Language="ES"]/Name', 'Value': 'El Grecco'},
    {'Path': 'Item/Genres/Genre', 'Value': 'Action'},
    {'Path': 'Item/Genres/Genre', 'Value': 'Drama'},
    {'Path': 'Item/Purchases/Purchase[@Country="US"]/HDPrice', 'Value': '10.99'},
    {'Path': 'Item/Purchases/Purchase[@Country="US"]/SDPrice', 'Value': '9.99'},
    {'Path': 'Item/Purchases/Purchase[@Country="CA"]/SDPrice', 'Value': '4.99'},
]

To parse each xpath step, I use the following RegEx (very simple one):

TAG_REGEX = r"(?P<tag>\w+)"
CONDITION_REGEX = r"(?P<condition>(?:\[.*?\])*)"
STEP_REGEX = TAG_REGEX + CONDITION_REGEX
ATTR_REGEX = r"@(?P<key>\w+)=\"(?P<value>.*?)\""

search_step = re.compile(STEP_REGEX, flags=re.DOTALL).search
findall_attr = re.compile(ATTR_REGEX, flags=re.DOTALL).findall


def parse_step(step):
    mo = search_step(step)
    if mo:
        tag = mo.group("tag")
        condition = mo.group("condition")
        return tag, dict(findall_attr(condition))
    raise ValueError(xpath)

The parse_step return a tag name and a attributes dictionary.

Then, I process the same way to build the XML tree:

root = None
for entry in entries:
    path = entry["Path"]
    parts = path.split("/")
    xpath_list = ["/" + parts[0]] + parts[1:]
    curr = root
    for xpath in xpath_list:
        tag_name, attrs = parse_step(xpath)
        if curr is None:
            root = curr = etree.Element(tag_name, **attrs)
        else:
            nodes = curr.xpath(xpath)
            if nodes:
                curr = nodes[0]
            else:
                curr = etree.SubElement(curr, tag_name, **attrs)
    if curr.text:
        curr = etree.SubElement(curr.getparent(), curr.tag, **curr.attrib)
    curr.text = entry["Value"]

print(etree.tostring(root, pretty_print=True))

The result is:

<Item>
  <Info>
    <Name>Body HD</Name>
    <Synopsis>A great movie</Synopsis>
  </Info>
  <Locales>
    <Locale Country="US" Language="ES">
      <Name>El Grecco</Name>
    </Locale>
  </Locales>
  <Genres>
    <Genre>Action</Genre>
    <Genre>Drama</Genre>
  </Genres>
  <Purchases>
    <Purchase Country="US">
      <HDPrice>10.99</HDPrice>
      <SDPrice>9.99</SDPrice>
    </Purchase>
    <Purchase Country="CA">
      <SDPrice>4.99</SDPrice>
    </Purchase>
  </Purchases>
</Item>

来源：https://stackoverflow.com/questions/38984272/write-xml-from-list-of-path-values