Replace text with HTML tag in LXML text element

I have some lxml element:

>> lxml_element.text
  'hello BREAK world'

I need to replace the word BREAK with an HTML break tag—<br />. I've tried to do simple text replacing:

lxml_element.text.replace('BREAK', '<br 开发者_如何学编程/>')

but it inserts the tag with escaped symbols, like <br/>. How do I solve this problem?

Here's how you could do it. Setting up a sample lxml from your question:

>>> import lxml
>>> some_data = "<b>hello BREAK world</b>"
>>> root = lxml.etree.fromstring(some_data)
>>> root
<Element b at 0x3f35a50>
>>> root.text
'hello BREAK world'

Next, create a subelement tag <br>:

>>> childbr = lxml.etree.SubElement(root, "br")
>>> childbr
<Element br at 0x3f35b40>
>>> lxml.etree.tostring(root)
'<b>hello BREAK world<br/></b>'

But that's not all you want. You have to take the text before the <br> and place it in .text:

>>> root.text = "hello"
>>> lxml.etree.tostring(root)
'<b>hello<br/></b>'

Then set the .tail of the child to contain the rest of the text:

>>> childbr.tail = "world"
>>> lxml.etree.tostring(root)
'<b>hello<br/>world</b>'

Well I don't think you want to just change the text node of the element. What I think you want to do is to modify the text node of your Element add a SubElement of name br to your lxml_element and then set the tail attribute of your subelement to the 2nd part of the string you are parsing. I found the tutorial here: http://lxml.de/tutorial.html#the-element-class to be very useful.