Recycled Knowledge: 2008/10

2008年10月14日

Here's some ideas for converting restricted forms of XML to good-quality JSON. The restrictions are as follows:

The XML can't contain mixed content (elements with both children/attributes and text).
The XML cannot depend on the order of child elements with distinct names (order dependence in children with the same name is okay).
There can't be any attributes with the same name as child elements.
There can't be any elements or attributes that differ only in their namespace names.

You also need to know the following things for each child element:

Whether it MUST appear at most once (a singleton element) or MAY appear more than once (a multiplex element).
Whether it only contains text (an element with simple type) or child elements and/or attributes (an element with complex-type).

Now, to convert the XML to JSON, apply these rules recursively:

A singleton element of simple type, and likewise an attribute, is converted to a JSON simple value: a number or boolean if syntactically possible, otherwise a string.
A multiplex object of simple type is converted to a JSON array of simple values.
A singleton element of complex type is converted to a JSON object that maps the local names of child elements and attributes to their content. Namespace names are discarded.
A multiplex element of complex type is mapped to a JSON array of JSON objects that map the local names of child elements and attributes to their content. Namespace names are discarded.

Comments are very welcome.

Posted by John Cowan at 00:27 5 comments:

Labels: xml

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John Cowan: New York, New York, United States; My friends say that I know at least something about practically everything; my enemies, that I know far too much about far too much. Here's the raw material for believing in both views. This is a personal blog. What I say here doesn't represent the views of my employer, Santa Claus, or anyone else. You can email me at cowan@ccil.org. Spams will be aggressively filtered.