You can pass the projection in as a keyword argument to any of the query
functions:
Article.all().run/fetch/get(projection=('title',))
On Tue, Apr 24, 2012 at 9:58 PM, Sun Jing <[email protected]> wrote:
> Thank you, Alfred.
> Can I change projection if I use Model.all() to create a Query object?
>
>
> On Wed, Apr 25, 2012 at 12:53 PM, Alfred Fuller <[email protected]>wrote:
>
>> Oh, also db.Query takes a class not a string, should be:
>> db.Query(Article, projection=('title',)).get()
>>
>> On Tue, Apr 24, 2012 at 9:09 PM, Alfred Fuller <[email protected]>wrote:
>>
>>> ('title') is not a tuple, you need to use ('title',) or ['title'] instead
>>>
>>> >>> print ('title')
>>> title
>>> >>> print ('title',)
>>> ('title',)
>>> >>>
>>>
>>> On Tue, Apr 24, 2012 at 8:58 PM, Sun Jing <[email protected]> wrote:
>>>
>>>> I tried to use projection queries:
>>>>
>>>> class Article(db.Model):
>>>> title = db.StringProperty(required=True)
>>>> # others...
>>>>
>>>> print db.Query('Article', projection=('title')).get()
>>>>
>>>>> Traceback (most recent call last):
>>>>> File
>>>>> "/base/python_runtime/python_lib/versions/1/google/appengine/ext/admin/__init__.py",
>>>>> line 331, in post
>>>>> exec(compiled_code, globals())
>>>>> File "<string>", line 3, in <module>
>>>>> File
>>>>> "/base/python_runtime/python_lib/versions/1/google/appengine/ext/db/__init__.py",
>>>>> line 2098, in get
>>>>> results = self.run(limit=1, **kwargs)
>>>>> File
>>>>> "/base/python_runtime/python_lib/versions/1/google/appengine/ext/db/__init__.py",
>>>>> line 2061, in run
>>>>> raw_query = self._get_query()
>>>>> File
>>>>> "/base/python_runtime/python_lib/versions/1/google/appengine/ext/db/__init__.py",
>>>>> line 2446, in _get_query
>>>>> kind = self._model_class.kind()
>>>>> AttributeError: 'str' object has no attribute 'kind'
>>>>
>>>>
>>>> print db.GqlQuery("SELECT title FROM Article").get().title
>>>> # this one works
>>>>
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>>>
>>>
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