how to add comment in xml subelement at element start

Question

I am using lxml in an attempt to to output the following xml code:

<?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>

This is my code, but the output is not correct:

from lxml import etree
with open('student.txt', 'r') as f:
    data = f.read()
root = etree.Element("root")
child1 = etree.SubElement(root, "students" )
child1.addprevious(etree.Comment('学生信息表 \n "id" : [名字, 数学, 语文, 英文]'))
child1.text = str(data)

# write to file:
tree = etree.ElementTree(root)
tree.write('student.xml', pretty_print=True, xml_declaration=True, encoding='utf-8')

The output xml is like this; comment is not in element <students>:

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

Please help me out on what I am doing wrong and how to proceed.

Maybe you would like to share with us what should be the correct output? If the correct output is trivial then would you like to share with us debugging details? — Ahmet
– Ahmet, Commented Nov 20, 2020 at 7:31
To make the code a proper minimal reproducible example, you need to show us the content of student.txt. — mzjn
– mzjn, Commented Nov 20, 2020 at 9:05
the content of student.txt : { "1" : ["张三", 150, 120, 100], "2" : ["李四", 90, 99, 95], "3" : ["王五", 60, 66, 68] } — Dogs He
– Dogs He, Commented Nov 21, 2020 at 12:52

Jack Fleeting · Accepted Answer · 2020-11-21 13:36:05Z

0

Try it this way:

students = """<?xml version="1.0" encoding="UTF-8"?>
<root>
    <students>        
        </students>
    </root> """

student_txt = """{ "1" : ["张三", 150, 120, 100], "2" : ["李四", 90, 99, 95], "3" : ["王五", 60, 66, 68]} """
    
from lxml import etree
doc = etree.XML(students.encode())

destination = doc.xpath('//students')[0]
destination.text=''    
new_comment = etree.Comment(student_txt)    
new_comment.tail = "\n"+student_txt

destination.insert(0, new_comment)
print(etree.tostring(doc).decode())

Output:

<root>
    <students><!--{ "1" : ["张三", 150, 120, 100], "2" : ["李四", 90, 99, 95], "3" : ["王五", 60, 66, 68]} -->
{ "1" : ["张三", 150, 120, 100], "2" : ["李四", 90, 99, 95], "3" : ["王五", 60, 66, 68]} </students>
</root>

answered Nov 21, 2020 at 13:36

Jack Fleeting

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1 Comment

Dogs He Over a year ago

new_comment = etree.Comment('学生信息表 \n "id" : [名字, 数学, 语文, 英文]')

Antoine Dubuis · Accepted Answer · 2020-11-20 08:53:46Z

0

Instead of using addprevious(), you should use insert as follows:

child1.insert(0, etree.Comment('学生信息表 \n "id" : [名字, 数学, 语文, 英文]'))

edited Nov 20, 2020 at 8:53

Antoine Dubuis

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answered Nov 20, 2020 at 7:30

pysona

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1 Comment

Dogs He Over a year ago

thks,I use this way,but the comment at the end of the element.I want before the element.How to?

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