dexml: a dead-simple Object-XML mapper for Python

Let’s face it: xml is a fact of modern life. I’d even go so far as to say that it’s good at what is does. But that doesn’t mean it’s easy to work with and it doesn’t mean that we have to like it. Most of the time, XML just needs to get out of the way and let you do some actual work instead of writing code to traverse and manipulate yet another DOM.

The dexml module takes the obvious mapping between XML tags and Python objects and lets you capture that as cleanly as possible. Loosely inspired by Django’s ORM, you write simple class definitions to define the expected structure of your XML document. Like so:

>>> import dexml2
>>> from dexml2 import fields
>>> class Person(dexml2.Model):
...   name = fields.String()
...   age = fields.Integer(tagname='age')

Then you can parse an XML document into an object like this:

>>> p = Person.parse("<Person name='Foo McBar'><age>42</age></Person>")
>>> p.name
u'Foo McBar'
>>> p.age
42

And you can render an object into an XML document like this:

>>> p = Person(name="Handsome B. Wonderful",age=36)
>>> p.render()
'<?xml version="1.0" ?><Person name="Handsome B. Wonderful"><age>36</age></Person>'

Malformed documents will raise a ParseError:

>>> p = Person.parse("<Person><age>92</age></Person>")
Traceback (most recent call last):
    ...
ParseError: required field not found: 'name'

Of course, it gets more interesting when you nest Model definitions, like this:

>>> class Group(dexml2.Model):
...   name = fields.String(attrname="name")
...   members = fields.List(Person)
...
>>> g = Group(name="Monty Python")
>>> g.members.append(Person(name="John Cleese",age=69))
>>> g.members.append(Person(name="Terry Jones",age=67))
>>> g.render(fragment=True)
'<Group name="Monty Python"><Person name="John Cleese"><age>69</age></Person><Person name="Terry Jones"><age>67</age></Person></Group>'

There’s support for XML namespaces, default field values, case-insensitive parsing, and more fun stuff. Check out the documentation on the following classes for more details:

Model:

the base class for objects that map into XML

Field:

the base class for individual model fields

Meta:

meta-information about how to parse/render a model