title: Unicode characters with BlobStore in App Engine
body: <p>Is there a way to store unicode data with App Engine's BlobStore (in Python)?</p>
  
  <p>I'm saving the data like this</p>
  
  <pre><code>file_name = files.blobstore.create(mime_type='application/octet-stream')
  with files.open(file_name, 'a') as f:
       f.write('&lt;as&gt;&lt;a&gt;' + '&lt;/a&gt;&lt;a&gt;'.join(stringInUnicode) + '&lt;/a&gt;&lt;/as&gt;')
  </code></pre>
  
  <p>But on the production (not development) server I'm getting this error. It seems to be converting my Unicode into ASCII and I don't know why.</p>
  
  <p>Why is it trying to convert back to ASCII? Can I avoid this?</p>
  
  <pre><code>    Traceback (most recent call last):
   File "/base/data/home/apps/myapp/1.349473606437967000/myfile.py", line 137, in get
     f.write('&lt;as&gt;&lt;a&gt;' + '&lt;/a&gt;&lt;a&gt;'.join(stringInUnicode) + '&lt;/a&gt;&lt;/as&gt;')
   File "/base/python_runtime/python_lib/versions/1/google/appengine/api/files/file.py", line 364, in write
     self._make_rpc_call_with_retry('Append', request, response)
   File "/base/python_runtime/python_lib/versions/1/google/appengine/api/files/file.py", line 472, in _make_rpc_call_with_retry
     _make_call(method, request, response)
   File "/base/python_runtime/python_lib/versions/1/google/appengine/api/files/file.py", line 226, in _make_call
     rpc.make_call(method, request, response)
   File "/base/python_runtime/python_lib/versions/1/google/appengine/api/apiproxy_stub_map.py", line 509, in make_call
     self.__rpc.MakeCall(self.__service, method, request, response)
   File "/base/python_runtime/python_lib/versions/1/google/appengine/api/apiproxy_rpc.py", line 115, in MakeCall
     self._MakeCallImpl()
   File "/base/python_runtime/python_lib/versions/1/google/appengine/runtime/apiproxy.py", line 161, in _MakeCallImpl
     self.request.Output(e)
   File "/base/python_runtime/python_lib/versions/1/google/net/proto/ProtocolBuffer.py", line 204, in Output
     self.OutputUnchecked(e)
   File "/base/python_runtime/python_lib/versions/1/google/appengine/api/files/file_service_pb.py", line 2390, in OutputUnchecked
     out.putPrefixedString(self.data_)
   File "/base/python_runtime/python_lib/versions/1/google/net/proto/ProtocolBuffer.py", line 432, in putPrefixedString
     v = str(v)
  UnicodeEncodeError: 'ascii' codec can't encode character u'\xe9' in position 313: ordinal not in range(128)
  </code></pre>