1

XML File:

<testcases>
    <mode>PRESSURE_CONTROL</mode>
    <category>ADULT</category>
    <testcase id="1">
        <parameter id="PEEP" value="1.000000">false</parameter>
        <parameter id="CMV_FREQ" value="4.0">false</parameter>
        <parameter id="PRESS_ABOVE_PEEP" value="0.0">true</parameter>
        <parameter id="I_E_RATIO" value="0.100000">false</parameter>
    </testcase>
</testcases>

Python code:

import xml.etree.ElementTree as ET

tree = ET.parse('Results.xml')    
root = tree.getroot()

mode = root.find('Mode').text
category = root.find('Category').text

        self.tag_invalid = ET.SubElement(root, 'invalid')    # For adding new  tag with attributes and values      
        for v in self.final_result:
            self.tag_testcase = ET.SubElement(self.tag_invalid, 'testcase')
            self.tag_testcase.attrib['id'] = 5
            self.tag_testcase.attrib['parameter'] = 'IE'
            self.tag_testcase.text = 100
            tree.write('/home/AlAhAb65/Desktop/test.xml')

Output:

<testcases>
    <mode>PRESSURE_CONTROL</mode>
    <category>ADULT</category>
    <testcase id="1">
        <parameter id="PEEP" value="1.000000">false</parameter>
        <parameter id="CMV_FREQ" value="4.0">false</parameter>
        <parameter id="PRESS_ABOVE_PEEP" value="0.0">true</parameter>
        <parameter id="I_E_RATIO" value="0.100000">false</parameter>
    </testcase>
<invalid><testcase id="5" parameter="I_E_RATIO">100.0</testcase></invalid></testcases>  # Extra line after python code running

The extra line is added in the XML file. But the problem is I cannot format it. That means I cannot add '\n', '\t' to maintain the hiererchy and format. Is there any rule for that? I tried tree.write(), ET.Element() functions. But those do not provide the desired result.

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4
  • 1
    With ET format of document depends on implementation. You don't have any control over it. Commented Apr 29, 2013 at 15:44
  • How can i maintain the hierarchy then? Commented Apr 29, 2013 at 15:48
  • It isn't clear from your incomplete code what you are trying to acheive. Please post a short, self-contained, runnable example program. Commented Apr 29, 2013 at 15:55
  • 1
    The hierarchy of an XML document is not related to newlines or line indentation. It has to do with the order of the XML elements. (So, <a><b>...</b></a> is a different hierarchy than <a>.</a><b>..</b>.) Commented Apr 29, 2013 at 16:01

3 Answers 3

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2

If you'd like the indentation of the XML text file to visually represent the hierarchy of the XML document, you need to pretty-print it. One way to do that is with xmllint --format:

$ xmllint --format test.xml 
<?xml version="1.0"?>
<testcases>
  <mode>PRESSURE_CONTROL</mode>
  <category>ADULT</category>
  <testcase id="1">
    <parameter id="PEEP" value="1.000000">false</parameter>
    <parameter id="CMV_FREQ" value="4.0">false</parameter>
    <parameter id="PRESS_ABOVE_PEEP" value="0.0">true</parameter>
    <parameter id="I_E_RATIO" value="0.100000">false</parameter>
  </testcase>
  <invalid>
    <testcase id="5" parameter="I_E_RATIO">100.0</testcase>
  </invalid>
</testcases>

If you'd like to generate the text file already pretty-printed, try reparsing it with a different XML library, for example minidom:

>>> print minidom.parseString(
            ET.tostring(
              tree.getroot(),
              'utf-8')).toprettyxml(indent=" ")

But note that each of these solutions changes the XML document. Strictly speaking, the resulting text files are not equivalent to the original -- the text elements have extra spaces and newlines added.

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Comments

2

You can control the text content of ElementTree elements using the attributes tail and text. E.g., try adding:

self.tag_invalid.text = "\n    "
self.tag_invalid.tail = "\n      "

Use that as a starting point, and try adding text/tail to the various other elements you create, print the results, and play around with it until it gives you what you want.

Here's an example showing what text and tail mean:

<A>TEXT_OF_A<B>TEXT_OF_B</B>TAIL_OF_B<C>TEXT_OF_C</C>TAIL_OF_C<D/>TAIL_OF_D</A>TAIL_OF_A

Alternatively, you can write a recursive function that walks through your xml tree, setting both text & tail attributes to properly indent it (relative to depth).

For more documentation on the text and tail attributes, see: http://docs.python.org/2/library/xml.etree.elementtree.html

EDIT: Take a look at http://effbot.org/zone/element-lib.htm#prettyprint to see an example of how you can recursively walk through the xml tree, setting text & tail so that all elements will be indented to their nesting depth.

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3 Comments

Thanks Edward Loper. Your answer was helpful. But I want to know is it possible to write just a tab "\t" in particular place without using tag. For example, ET.anymethod('\t') or ET.Element('\t') or something like that. Not using self.tag.text or self.tag.tail. Thanks again
Because consider about very first tag. If you need to write \t or \n before that, how can you do that? because u have not make tag
The .text and .tail elements cover all places where you could potentially want to put text. Take a look at my example to see what I mean. If you want to put a \t after the element e's open tag (but before any contained elements), then use e.text. If you want to put it after e's close tag, then use e.tail. If you want to put text "between" two elements, then use the first element's tail. It's true that you can't put text before the top-level element (<testcases> in your example), but you can put text anywhere else.
0

According to ET manual:

Writes an element tree or element structure to sys.stdout. This function should be used for debugging only.

The exact output format is implementation dependent. In this version, it’s written as an ordinary XML file.

But there are some fixes for that on google.

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