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Generating Markup Programmatically

Genshi provides a builder module which lets you generate markup from Python code using a very simple syntax. The main entry point to the builder module is the tag object (which is actually an instance of the ElementFactory class). You should rarely (if ever) need to directly import and use any of the other classes in the builder module.

1   Creating Elements

Elements can be created through the tag object using attribute access, for example:

>>> from genshi.builder import tag
>>> doc = tag.p('Some text and ', tag.a('a link', href='http://example.org/'), '.')
>>> doc
<Element "p">

This produces an Element instance which can be further modified to add child nodes and attributes. This is done by “calling” the element: positional arguments are added as child nodes (alternatively, the append method can be used for that purpose), whereas keywords arguments are added as attributes:

>>> doc(tag.br)
<Element "p">
>>> print doc
<p>Some text and <a href="http://example.org/">a link</a>.<br/></p>

If an attribute name collides with a Python keyword, simply append an underscore to the name:

>>> doc(class_='intro')
<Element "p">
>>> print doc
<p class="intro">Some text and <a href="http://example.org/">a link</a>.<br/></p>

As shown above, an Element can easily be directly rendered to XML text by printing it or using the Python str() function. This is basically a shortcut for converting the Element to a stream and serializing that stream:

>>> stream = doc.generate()
>>> stream
<genshi.core.Stream object at 0x72d230>
>>> print stream
<p class="intro">Some text and <a href="http://example.org/">a link</a>.<br/></p>

2   Creating Fragments

The tag object also allows creating “fragments”, which are basically lists of nodes (elements or text) that don't have a parent element. This can be useful for creating snippets of markup that are attached to a parent element later (for example in a template). Fragments are created by calling the tag object:

>>> fragment = tag('Hello, ', tag.em('word'), '!')
>>> fragment
>>> print fragment
Hello, <em>world</em>!

See also: genshi.builder, Documentation, Markup streams

Last modified 3 years ago Last modified on Dec 14, 2015 6:22:32 AM