将属性添加到xml.etree.ElementTree的元素，并使其可序列化为XML

Question

我想从xml.etree.ElementTree中向Element某些实例添加属性，以便将诸如numpy.ndarray卫星数据存储到某些树的节点中。 因为对象不公开__dict__和__slot__是有可能的吗？

我知道我可以使用get / set方法填充node属性，但是如果它包含str以外的其他对象，则不能将其序列化为XML。

Traceback (most recent call last):
  File "latexer.py", line 576, in <module>
    main(sys.argv)
  File "latexer.py", line 565, in main
    r.dump(**k)
  File "latexer.py", line 406, in dump
    code = self.__fileFormats[ufformat]()
  File "latexer.py", line 416, in getXML
    rawstr = ET.tostring(self._document, encoding='utf-8', method='xml')
  File "C:\Python33\lib\xml\etree\ElementTree.py", line 1171, in tostring
    ElementTree(element).write(stream, encoding, method=method)
  File "C:\Python33\lib\xml\etree\ElementTree.py", line 828, in write
    serialize(write, self._root, qnames, namespaces)
  File "C:\Python33\lib\xml\etree\ElementTree.py", line 990, in _serialize_xml
    _serialize_xml(write, e, qnames, None)
  File "C:\Python33\lib\xml\etree\ElementTree.py", line 990, in _serialize_xml
    _serialize_xml(write, e, qnames, None)
  File "C:\Python33\lib\xml\etree\ElementTree.py", line 990, in _serialize_xml
    _serialize_xml(write, e, qnames, None)
  File "C:\Python33\lib\xml\etree\ElementTree.py", line 983, in _serialize_xml
    v = _escape_attrib(v)
  File "C:\Python33\lib\xml\etree\ElementTree.py", line 1139, in _escape_attrib
    _raise_serialization_error(text)
  File "C:\Python33\lib\xml\etree\ElementTree.py", line 1105, in _raise_serialization_error
    "cannot serialize %r (type %s)" % (text, type(text).__name__)
TypeError: cannot serialize 1 (type int)

有没有一种方法可以添加诸如bool或integer属性，然后将其序列化为XML？

Answer 1

在阅读了有关此问题的其他文章之后，我接受了对该问题没有直接，优雅的解决方案，因为–出于充分的理由–可以将所有对象都隐式转换为字符串。

然后，我找到了一种中间方法。 该技术包括腌制六角形的物体。 当我要访问它时，只需调用相反的过程即可。

我知道这在数据存储和计算开销方面不是很有效，但是它可以解决我的问题，因为我的树需要转储为XML并在以后重新打开。

代码如下：

def _fillNode(self, node, text=None, **kwargs):
    """Fill a given node with text and arguments (serialized if non string) from kwargs"""
    node.text = text
    for (k, v) in kwargs.items():
        # Append string as this:
        if isinstance(v, str):
            node.set(k, v)
        # If not a string pickle, hexlify and encode: 
        else:
            node.set(k, binascii.hexlify(pickle.dumps(v)).decode())
    return node

def _getAttribute(self, node, key, default=None):
    """Get node attribute as string but try first to deserialize it"""
    # Try to recover string formated data:
    value = node.get(key)
    if value:
        try:
            # try to decode, unhexlify and unpickle:
            return pickle.loads(binascii.unhexlify(value.encode()))
        except:
            # If not return as this
            return value
    else:
        return default