Pretty printing XML files on Emacs

Question

I use emacs to edit my xml files (nxml-mode) and the files were generated by machine don't have any pretty formatting of the tags.

I have searched for pretty printing the entire file with indentation and saving it, but wasn't able to find an automatic way.

Is there a way? Or atleast some editor on linux which can do it.

Answer 1

I use nXML mode for editing and Tidy when I want to format and indent XML or HTML. There is also an Emacs interface to Tidy.

Answer 2

Tidy looks like a good mode. Must look at it. Will use it if I really need all the features it offers.

Anyway, this problem was nagging me for about a week and I wasn't searching properly. After posting, I started searching and found one site with an elisp function which does it pretty good. The author also suggests using Tidy.

Thanks for answer Marcel (too bad I don't have enough points to upmod you).

Will post about it soon on my blog. Here is a post about it (with a link to Marcel's site).

Answer 3

1. Emacs nxml-mode can work on presented format, but you'll have to split the lines.
2. For longer files that simply isn't worth it. Run this stylesheet (ideally with Saxon which IMHO gets the line indents about right) against longer files to get a nice pretty print. For any elements where you want to retain white space add their names alongside 'programlisting' as in 'programlisting yourElementName'

HTH

Answer 4

If you only need pretty indenting without introducing any new line-breaks, you can apply the indent-region command to the entire buffer with these keystrokes:

C-x h
C-M-\

If you also need to introduce line-breaks, so that opening and closing tags are on separate lines, you could use the following very nice elisp function, written by Benjamin Ferrari. I found it on his blog and hope it's ok for me to reproduce it here:

(defun bf-pretty-print-xml-region (begin end)
  "Pretty format XML markup in region. You need to have nxml-mode
http://www.emacswiki.org/cgi-bin/wiki/NxmlMode installed to do
this.  The function inserts linebreaks to separate tags that have
nothing but whitespace between them.  It then indents the markup
by using nxml's indentation rules."
  (interactive "r")
  (save-excursion
      (nxml-mode)
      (goto-char begin)
      (while (search-forward-regexp "\>[ \\t]*\<" nil t) 
        (backward-char) (insert "\n"))
      (indent-region begin end))
    (message "Ah, much better!"))

This doesn't rely on an external tool like Tidy.

Answer 5

You don't even need to write your own function - sgml-mode (a gnu emacs core module) has a built-in pretty printing function called (sgml-pretty-print ...) which takes region beginning and end arguments.

If you are cutting and pasting xml and you find your terminal is chopping the lines in arbitrary places you can use this pretty printer which fixes broken lines first.

Answer 6

I'm afraid I like Benjamin Ferrari version much better. The internal pretty print always places the end tag in a new line after the value, inserting unwanted CR in the tag values.

Answer 7

Emacs can run arbitrary commands with M-|. If you have xmllint installed:

"M-| xmllint --format -" will format the selected region

"C-u M-| xmllint --format -" will do the same, replacing the region with the output