Bug: dict value with unsupported type fails silently

[quandyfactory]

If you pass in a dict and one of the values is an unsupported type (e.g. a datetime object), the code doesn't raise an exception - it just passes silently over the value without adding it to the XML output. Here's an example that produces the issue:

>>> import dict2xml
>>> import datetime
>>> now = datetime.datetime.today()
>>> mydict = { 'name': 'Joe Blow', 'time': now }
>>> xml = dict2xml.dict2xml(mydict)
>>> print xml
<?xml version="1.0" encoding="UTF-8" ?><root><name type="str">Joe Blow</name></root>
>>> # the 'time' key and its datetime value just silently disappeared

I propose the following fix:

• Raise an exception in convert_dict() and convert_list() if one of the elements is an unsupported type (currently, only convert() raises an exception).
• Include an optional parameter that will automatically convert datetimes into UTC strings in the XML output.
• Include an optional parameter that will automatically convert other unsupported types into their string representations.

[quandyfactory]

One easy way to handle datetimes is to check an object for hasattr(obj, 'isoformat') and return obj.isoformat() if it does.

[quandyfactory]

Fixed in release 0.5. Now supports datetime (converts to ISO format string) and set (converts to list) data types, and raises a TypeError exception on an unsupported data type.