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A dead-simple xml object mapper for Python

Project description

dexml: An Object-XML Mapper for Python

This is a maintained version of the original dexml Python package, intended for Python 3 use only.

Other than providing a maintained version that supports modern Python 3, other future goals include:

  • support with Python dataclasses and pydantic models
  • support for auto-generating models based on example XML payloads
  • keep backwards compatibility with original dexml package where possible

Before refactoring, the original code was sourced from both:

Installation

pip install dexml-python

Documentation

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 it 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 dexml
  >>> from dexml import fields
  >>> class Person(dexml.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(dexml.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

Auto-Generating Models

You can generate Python code with dexml models from XML using the following command:

cat file.xml | python -m dexml > model.py

Only the Model, String, Integer, Float, and Boolean fields are currently supported.

Generation is not intended to be 100% perfect but as a starting point for manually creating large models.

Development

The project uses poetry to manage dependencies, virtual environments, and publishing.

It also uses pre-commit to provide some standard git hook checks.

The Makefile has some shortcuts for common operations. After cloning, the following steps can be taken:

  1. Run make restore
  2. Optionally enter virtual environment with poetry shell
  3. Run make test
  4. Run make build to create a distribution

Contributing

This is an early stage project but pull requests are welcome.

Project details


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