Error With AlchemyAPI Python SDK

Question

I am trying to use AlchemyAPI Python 0.7 SDK. However when ever I run a method within it e.g. URLGetText(url);

I get this error:

    nodes = etree.fromstring(result).xpath(xpathQuery)
  File "lxml.etree.pyx", line 2743, in lxml.etree.fromstring (src/lxml/lxml.etree.c:52665)
  File "parser.pxi", line 1573, in lxml.etree._parseMemoryDocument (src/lxml/lxml.etree.c:79932)
  File "parser.pxi", line 1452, in lxml.etree._parseDoc (src/lxml/lxml.etree.c:78774)
  File "parser.pxi", line 960, in lxml.etree._BaseParser._parseDoc (src/lxml/lxml.etree.c:75389)
  File "parser.pxi", line 564, in lxml.etree._ParserContext._handleParseResultDoc (src/lxml/lxml.etree.c:71739)
  File "parser.pxi", line 645, in lxml.etree._handleParseResult (src/lxml/lxml.etree.c:72614)
  File "parser.pxi", line 585, in lxml.etree._raiseParseError (src/lxml/lxml.etree.c:71955)
lxml.etree.XMLSyntaxError: AttValue: " or ' expected, line 19, column 11

This come from this area of code:

  def GetRequest(self, apiCall, apiPrefix, paramObject):
    endpoint = 'http://' + self._hostPrefix + '.alchemyapi.com/calls/' + apiPrefix + '/' + apiCall
    endpoint += '?apikey=' + self._apiKey + paramObject.getParameterString()
    handle = urllib.urlopen(endpoint)
    result = handle.read()
    handle.close()
    xpathQuery = '/results/status'
    nodes = etree.fromstring(result).xpath(xpathQuery)
    if nodes[0].text != "OK":
      raise Exception, 'Error making API call.'
    return result

Any one have any ideas about what is going wrong?

Thank You

Daniel Kershaw

Answer 1

I looked at the Python urllib docs, and found this page:

http://docs.python.org/library/urllib.html#high-level-interface

which contains this warning about the filehandle object returned by urllib.urlopen():

One caveat: the read() method, if the size argument is omitted or negative, may not read until the end of the data stream; there is no good way to determine that the entire stream from a socket has been read in the general case.

I think maybe you should ensure that you obtain the entire contents of the file as a Python string before parsing it with the etree.fromstring() API. Something like:

result = ''
while (1):
    next = handle.read()
    if not next: 
        break
    result += next