Add a newline after each closing html tag in web2py

Original

I want to parse a string of html code and add newlines after closing tags + after the initial form tag. Here's the code so far. It's giving me an error in the "re.sub" line. I don't understand why the regex fails.

def user(): 
    tags = "<form><label for=\"email_field\">Email:</label><input type=\"email\" name=\"email_field\"/><label for=\"password_field\">Password:</label><input type=\"password\" name=\"password_field\"/><input type=\"submit\" value=\"Login\"/></form>"
    result = re.sub("(</.*?>)", "\1\n", tags)
    return dict(form_code=result)

PS. I have a feeling this might not be the best way... but I still want to learn how to do this.

EDIT

I was missing "import re" from my default.py. Thanks ruakh for this.

import re

Now my page source code shows up like this (inspected in client browser). The actual page shows the form code as text, not as UI elements.

&lt;form&gt;&lt;label for=&quot;email_field&quot;&gt;Email:&lt;/label&gt;
&lt;input type=&quot;email&quot; name=&quot;email_field&quot;/&gt;&lt;label     
for=&quot;password_field&quot;&gt;Password:&lt;/label&gt;
&lt;input type=&quot;password&quot; name=&quot;password_field&quot;/&gt;&lt;input   
type=&quot;submit&quot; value=&quot;Login&quot;/&gt;&lt;/form&gt;

EDIT 2

The form code is rendered as UI elements after adding XML() helper into default.py. Thanks Anthony for helping. Corrected line below:

return dict(form_code=XML(result))

FINAL EDIT

Fixing the regex I figured myself. This is not optimal solution but at least it works. The final code:

import re
def user(): 
    tags = "<form><label for=\"email_field\">Email:</label><input type=\"email\" name=\"email_field\"/><label for=\"password_field\">Password:</label><input type=\"password\" name=\"password_field\"/><input type=\"submit\" value=\"Login\"/></form>"
    tags = re.sub(r"(<form>)", r"<form>\n  ", tags)
    tags = re.sub(r"(</.*?>)", r"\1\n  ", tags)
    tags = re.sub(r"(/>)", r"/>\n  ", tags)
    tags = re.sub(r"(  </form>)", r"</form>\n", tags)
    return dict(form_code=XML(tags))

Solution

The only issue I see is that you need to change "\1\n" to r"\1\n" (using the "raw" string notation); otherwise \1 is interpreted as an octal escape (meaning the character U+0001). But that shouldn't give you an error, per se. What error-message are you getting?