CODEWITHSUNDEEP
pythonxmllxml
red_herring
red_herring

Reputation: 167

Adding a comment to an element and making the element text appear after the comment

I want to save an XML file with a comment, but even if I add the comment before adding the text, the comment appears after the text in the output. My code and output is below.

def save_xml(data):
    root = etree.Element('root')
    student_xml = etree.ElementTree(root)
    student = etree.SubElement(root,'students')
    student.append(etree.Comment('\n学生信息表\n\"id\": [名字，数学，语文，英语]\n'))
    student.text = str(data)
    file = open('student.xml', 'w',encoding='utf-8')
    file.write(etree.tounicode(student_xml.getroot()))
    file.close()


<root><students>{1: ['张三', 150, 120, 100], 2: ['李四', 90, 99, 95], 3: ['王 五', 60, 66, 68]}<!--
学生信息表
"id": [名字，数学，语文，英语]
--></students></root>

And I want the output like below.

<?xml version="1.0" encoding="UTF-8"?>
<root>
<students>
<!--
    学生信息表
    "id" : [名字, 数学, 语文, 英文]
-->
{
    "1" : ["张三", 150, 120, 100],
    "2" : ["李四", 90, 99, 95],
    "3" : ["王五", 60, 66, 68]
}
</students>
</root>

Upvotes: 3

Views: 1704

Answers (1)

mzjn
mzjn

Reputation: 50967

Add the text as the tail of the comment node.

student = etree.SubElement(root, 'students')
comment = etree.Comment('\n学生信息表\n\"id\": [名字，数学，语文，英语]\n')
comment.tail = "\n" + str(data)
student.append(comment)

The tail property contains the text immediately following an element (a comment is a special type of element node).

See also https://lxml.de/tutorial.html#elements-contain-text and http://infohost.nmt.edu/~shipman/soft/pylxml/web/etree-view.html.

If pretty-printing is important, there are a few things you can do:

  1. Serialize using pretty_print=True.

  2. Use pprint.pformat() to format the data dictionary.

  3. Add some extra whitespace in a few places.

Complete example:

from lxml import etree
from pprint import pformat

data = {
    "1" : ["张三", 150, 120, 100],
    "2" : ["李四", 90, 99, 95],
    "3" : ["王五", 60, 66, 68]
}

root = etree.Element('root')

student = etree.SubElement(root, 'students')
student.text = "\n"
comment = etree.Comment('\n     学生信息表\n     \"id\": [名字，数学，语文，英语]\n')
comment.tail = "\n" + pformat(data, width=35) + "\n"
student.append(comment)

etree.ElementTree(root).write("students.xml", pretty_print=True,
                              encoding="UTF-8", xml_declaration=True)

Contents of students.xml:

<?xml version='1.0' encoding='UTF-8'?>
<root>
  <students>
<!--
     学生信息表
     "id": [名字，数学，语文，英语]
-->
{'1': ['张三', 150, 120, 100],
 '2': ['李四', 90, 99, 95],
 '3': ['王五', 60, 66, 68]}
</students>
</root>

Upvotes: 2

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