如何在元素开始时在xml子元素中添加注释

Question

我使用lxml试图输出以下xml代码：

<?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> 

这是我的代码，但输出不正确：

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')

输出xml如下所示；注释不在元素<students>中：

<?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>

请帮我解决我做错了什么以及如何继续

Answer 1

试着这样做：

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())

输出：

<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>

Answer 2

不应使用addprevious()，而应按如下方式使用insert：

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