gae python ascii codec cant decode byte

Question

When I run my application, which finds links, checks if they exist in the database, and adds them to the database, I get an error.

Traceback (most recent call last):
  File "/base/python27_runtime/python27_lib/versions/third_party/webapp2-2.5.1/webapp2.py", line 1536, in __call__
    rv = self.handle_exception(request, response, e)
  File "/base/python27_runtime/python27_lib/versions/third_party/webapp2-2.5.1/webapp2.py", line 1530, in __call__
    rv = self.router.dispatch(request, response)
  File "/base/python27_runtime/python27_lib/versions/third_party/webapp2-2.5.1/webapp2.py", line 1278, in default_dispatcher
    return route.handler_adapter(request, response)
  File "/base/python27_runtime/python27_lib/versions/third_party/webapp2-2.5.1/webapp2.py", line 1102, in __call__
    return handler.dispatch()
  File "/base/python27_runtime/python27_lib/versions/third_party/webapp2-2.5.1/webapp2.py", line 572, in dispatch
    return self.handle_exception(e, self.app.debug)
  File "/base/python27_runtime/python27_lib/versions/third_party/webapp2-2.5.1/webapp2.py", line 570, in dispatch
    return method(*args, **kwargs)
  File "/base/data/home/apps/s~nothing-but-net/1.360769209191920043/main.py", line 460, in get
    blchrlinks(True, a)
  File "/base/data/home/apps/s~nothing-but-net/1.360769209191920043/main.py", line 271, in blchrlinks
    if Articles.by_name(title):
  File "/base/data/home/apps/s~nothing-but-net/1.360769209191920043/main.py", line 498, in by_name
    u = Articles.all().filter("name =", name).get()
  File "/base/python27_runtime/python27_lib/versions/1/google/appengine/ext/db/__init__.py", line 2099, in get
    results = self.run(limit=1, **kwargs)
  File "/base/python27_runtime/python27_lib/versions/1/google/appengine/ext/db/__init__.py", line 2063, in run
    iterator = raw_query.Run(**kwargs)
  File "/base/python27_runtime/python27_lib/versions/1/google/appengine/api/datastore.py", line 1622, in Run
    itr = Iterator(self.GetBatcher(config=config))
  File "/base/python27_runtime/python27_lib/versions/1/google/appengine/api/datastore.py", line 1601, in GetBatcher
    return self.GetQuery().run(_GetConnection(), query_options)
  File "/base/python27_runtime/python27_lib/versions/1/google/appengine/api/datastore.py", line 1490, in GetQuery
    filter_predicate=self.GetFilterPredicate(),
  File "/base/python27_runtime/python27_lib/versions/1/google/appengine/api/datastore.py", line 1534, in GetFilterPredicate
    property_filters.append(datastore_query.make_filter(name, op, values))
  File "/base/python27_runtime/python27_lib/versions/1/google/appengine/datastore/datastore_query.py", line 107, in make_filter
    properties = datastore_types.ToPropertyPb(name, values)
  File "/base/python27_runtime/python27_lib/versions/1/google/appengine/api/datastore_types.py", line 1745, in ToPropertyPb
    pbvalue = pack_prop(name, v, pb.mutable_value())
  File "/base/python27_runtime/python27_lib/versions/1/google/appengine/api/datastore_types.py", line 1556, in PackString
    pbvalue.set_stringvalue(unicode(value).encode('utf-8'))
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc2 in position 57: ordinal not in range(128)

My code for by_name is:

def by_name(cls, name):
    u = Articles.all().filter("name =", name).get()
    return u

Answer 1

As the last line of the stack trace shows, it's trying to convert the value to unicode first and then encoding it as utf-8. However, the (implicit) conversion is using ascii, which is not enough for your string. You could try converting it to unicode yourself, using the right encoding, before passing it to filter . Example:

u = Articles.all().filter("name =", name.decode('utf-8')).get()

(remember that you need to provide the correct encoding; if name is not a UTF-8 string, but a Cp1252, ISO-Latin or something else, you need to specify that in the decode call)