i was looking at sixohsix Twitter wrapper trying to understand the code and found out that for example:
t = Twitter(...)
t.statuses.home_timeline()
Theres no statuses or home_timeline methods or attributes in the Twitter class or TwitterCall, so clearly im missing some python magic in here. Could anyone explain me whats going on there?
thanks so much in advance!
Basically Twitter is a subclass of TwitterCall and the magic takes place in __getattr__. If you're accessing an attribute that doesn't exist you'll get an AttributeError.
When that happens it runs extend_call with that attribute as argument and that'll call self.callable_cls (which also happens to be TwitterCall). This result in another TwitterCall object. The same trick is then repeated because it'll discover that home_timeline doesn't exist on that object either. It'll then call this object (because you're writing home_timeline()) and that makes a HTTP request to Twitter.
The easiest way is to step through the code to see what's going on. When you're accessing an attribute you need to read __getattr__ and when you're making a method call you need to read __call__.
There is, line 141. You should read about __getattr__.
In your example, all attributes not defined for TwitterCall class (or its descendant Twitter), that is, if AttributeError is raised by object.__getattr__, are recursively translated to a call to Twitter API, with uriparts combining all the attributes in a tuple.
So in your example, a call to statuses.home_timeline uri will be made in the end of recursion.
Related
I am using PyObj-C and am making some methods in a python file to read and write files using NSDocument, which uses the abstract NSFileCoordinater class. Accessing files this way instead of just using python's open let's these classes handle things for me such as preventing files from being edited from more than one program at a time or giving enough time for read/write operations to finish before it could get deadlocked.
These features are very important, and the app I ma building I want to be up to standard as much as I can here.
I have this code that instantiates a NSDocument object that contains the content of whatever file path you put into it, as a function:
#classmethod
def write(cls, file: str):
path = NSURL.fileURLWithPath_(file)
ext = file.split('.')[-1]
doc = NSDocument.alloc().initWithContentsOfURL_ofType_error_(path, ext, None)
When I call this function with a valid file path I get this error:
File "/Users/user123/PycharmProjects/shoutout/src/sutils/cfiles.py", line 27, in write
doc = NSDocument.alloc().initWithContentsOfURL_ofType_error_(path, ext, None)
objc.error: NSInternalInconsistencyException - readFromData:ofType:error: is a subclass responsibility but has not been overridden.
I have tried to find forums both objective-c, swift, or pyobj-c based as it were asking any keywords such as objective-c is a subclass responsibility but has not been overridden on google, and checked stackoverflow, and github for existing posts on this error but I could find none.
As I understand it Objective-C being polymorphic, has my method initWithContentsOfURL:ofType:error: call readFromData:ofType:error, among other ones at the same time. I don't understand exactly however what it means when it's saying that "is a subclass responsibility but has not been overridden." I am not sure also about what it means to override a class or a one being a responsibility so that doesn't help on my part.
A NSInternalInconsistencyException means a "when an internal assertion fails and implies an unexpected condition within the called code." Not sure what a internal "assertion" is either or what this could mean.
Any idea of what I could do to fix this?
NSDocument is an abstract class that requires you to subclass and implement a number of methods to make it usable. This is document in Apple's documentation for the class.
the older Document-Baed App Programming Guide for Mac gives more information on this.
I am trying to write a testing program for a python program that takes data, does calculations on it, then puts the output in a class instance object. This object contains several other objects, each with their own attributes. I'm trying to access all the attributes and sub-attributes dynamically with a one size fits all solution, corresponding to elements in a dictionary I wrote to cycle through and get all those attributes for printing onto a test output file.
Edit: this may not be clear from the above but I have a list of the attributes I want, so using something to actually get those attributes is not a problem, although I'm aware python has methods that accomplish this. What I need to do is to be able to get all of those attributes with the same function call, regardless of whether they are top level object attributes or attributes of object attributes.
Python is having some trouble with this - first I tried doing something like this:
for string in attr_dictionary:
...
outputFile.print(outputclass.string)
...
But Python did not like this, and returned an AttributeError
After checking SE, I learned that this is a supposed solution:
for string in attr_dictionary:
...
outputFile.print(getattr(outputclass, string))
...
The only problem is - I want to dynamically access the attributes of objects that are attributes of outputclass. So ideally it would be something like outputclass.objectAttribute.attribute, but this does not work in python. When I use getattr(outputclass, objectAttribute.string), python returns an AttributeError
Any good solution here?
One thing I have thought of trying is creating methods to return those sub-attributes, something like:
class outputObject:
...
def attributeIWant(self,...):
return self.subObject.attributeIWant
...
Even then, it seems like getattr() will return an error because attributeIWant() is supposed to be a function call, it's not actually an attribute. I'm not certain that this is even within the capabilities of Python to make this happen.
Thank you in advance for reading and/or responding, if anyone is familiar with a way to do this it would save me a bunch of refactoring or additional code.
edit: Additional Clarification
The class for example is outputData, and inside that class you could have and instance of the class furtherData, which has the attribute dataIWant:
class outputData:
example: furtherData
example = furtherData()
example.dataIWant = someData
...
with the python getattr I can't access both attributes directly in outputData and attributes of example unless I use separate calls, the attribute of example needs two calls to getattr.
Edit2: I have found a solution I think works for this, see below
I was able to figure this out - I just wrote a quick function that splits the attribute string (for example outputObj.subObj.propertyIWant) then proceeds down the resultant array, calling getattr on each subobject until it reaches the end of the array and returns the actual attribute.
Code:
def obtainAttribute(sample, attributeString: str):
baseObj = sample
attrArray = attributeString.split(".")
for string in attrArray:
if(attrArray.index(string) == (len(attrArray) - 1)):
return getattr(baseObj,string)
else:
baseObj = getattr(baseObj,string)
return "failed"
sample is the object and attributeString is, for example object.subObject.attributeYouWant
I have an object method which changes an attribute of an object. Another method (the one I'm trying to test) calls the first method multiple times and afterward uses the attribute that was modified. How can I test the second method while explicitly saying how the first method changed that attribute?
For example:
def method_to_test(self):
output = []
for _ in range(5):
self.other_method()
output.append(self.attribute_changed_by_other_method)
return output
I want to specify some specific values that attribute_changed_by_other_method will become due to other_method (and the real other_method uses probabilities in deciding on how to change attribute_changed_by_other_method).
I'm guessing the best way to do this would be to "mock" the attribute attribute_changed_by_other_method so that on each time the value is read it gives back a different value of my specification. I can't seem to find how to do this though. The other option I see would be to make sure other_method is mocked to update the attribute in a defined way each time, but I don't know of a particularly clean way of doing this. Can someone suggest a reasonable way of going about this? Thank you much.
What you can actually do is use flexmock for other_method. What you can do with flexmock is set a mock on an instance of your class. Here is an example of how to use it:
class MyTestClass(unittest.TestCase):
def setUp(self):
self.my_obj = MyClass()
self.my_obj_mock = flexmock(self.my_obj)
def my_test_case(self):
self.my_obj_mock.should_receive('other_method').and_return(1).and_return(2).and_return(3)
self.my_obj.method_to_test()
So, what is happening here is that on your instance of MyClass, you are creating a flexmock object out of self.my_obj. Then in your test case, you are stating that when you make your call to method_to_test, you should receive other_method, and each call to it should return 1, 2, 3 respectively.
Furthermore, if you are still interested in knowing how to mock out attribute_changed_by_other_method, you can use Mock's PropertyMock:
Hope this helps. Let me know how it goes!
For anyone still looking for a straightforward answer, this can be done easily with PropertyMock as the accepted answer suggests. Here is one way to do it.
from unittest.mock import patch, PropertyMock
with patch("method_your_class_or_method_calls", new_callable=PropertyMock) as mock_call:
mock_call.side_effect = [111, 222]
class_or_method()
Each subsequent call of that patched method will return that list in sequence.
I made a command in django which calls a function.
That function does a django orm call:
def get_notes():
notes = Note.objects.filter(number=2, new=1)
return [x.note for x in notes]
I want to patch the actual lookup:
#mock.patch('Note.objects.filter', autospec=True)
def test_get_all_notes(self, notes_mock):
get_notes()
notes_mock.assert_called_once_with(number=2, new=1)
I get the following assertion error:
AssertionError: Expected call: filter(number=2, new=1)
Actual call: filter(number=2, new=1)
I search on google and stackoverflow for hours, but I still haven't a clue.
Can anyone point me in the right direction, I think it might be an obvious mistake I'm making...
AFAIK you can't use patch() like this. Patch target should be a string in the form package.module.ClassName. I don't know much about django but I suppose Note is a class so Note.objects.filter is not something you can import and hence use in patch(). Also I don't think patch() can handle attributes. Actually I don't quite understand why the patch works at all.
Try using patch.object() which is specifically designed to patch class attributes. It implies Note is already imported in your test module.
#mock.patch.object(Note, 'objects')
def test_get_all_notes(self, objects_mock):
get_notes()
objects_mock.filter.assert_called_once_with(number=2, new=1)
I've removed autospec because I'm not sure it will work correctly in this case. You can try putting it back if it works.
Another option might be to use patch() on whatever you get with type(Note.objects) (probably some django class).
As I've said I don't know much about django so I'm not sure if these things work.
I have a queryset that I need to pickle lazily and I am having some serious troubles. cPickle.dumps(queryset.query) throws the following error:
Can't pickle <class 'myproject.myapp.models.myfile.QuerySet'>: it's not the same object as myproject.myapp.models.myfile.QuerySet
Strangely (or perhaps not so strangely), I only get that error when I call cPcikle from another method or a view, but not when I call it from the command line.
I made the method below after reading PicklingError: Can't pickle <class 'decimal.Decimal'>: it's not the same object as decimal.Decimal and Django mod_wsgi PicklingError while saving object:
def dump_queryset(queryset, model):
from segment.segmentengine.models.segment import QuerySet
memo = {}
new_queryset = deepcopy(queryset, memo)
memo = {}
new_query = deepcopy(new_queryset.query, memo)
queryset = QuerySet(model=model, query=new_query)
return cPickle.dumps(queryset.query)
As you can see, I am getting extremely desperate -- that method still yields the same error. Is there a known, non-hacky solution to this problem?
EDIT: Tried using --noreload running on the django development server, but to no avail.
EDIT2: I had a typo in the error I displayed above -- it was models.QuerySet, not models.mymodel.QuerySet that it was complaining about. There is another nuance here, which is that my models file is broken out into multiple modules, so the error is ACTUALLY:
Can't pickle <class 'myproject.myapp.models.myfile.QuerySet'>: it's not the same object as myproject.myapp.models.myfile.QuerySet
Where myfile is one of the modules under models. I have an __ini__.py in models with the following line:
from myfile import *
I wonder if this is contributing to my issue. Is there some way to change my init to protect myself against this? Are there any other tests to try?
EDIT3: Here is a little more background on my use case: I have a model called Context that I use to populate a UI element with instances of mymodel. The user can add/remove/manipulate the objects on the UI side, changing their context, and when they return, they can keep their changes, because the context serialized everything. A context has a generic foreign key to different types of filters/ways the user can manipulate the object, all of which must implement a few methods that the context uses to figure out what it should display. One such filter takes a queryset that can be passed in and displays all of the objects in that queryset. This provides a way to pass in arbitrary querysets that are produced elsewhere and have them displayed in the UI element. The model that uses the Context is hierarchical (using mptt for this), and the UI element makes a request to get children each time the user clicks around, we can then take the children and determine if they should be displayed based on whether or not they are included in the Context. Hope that helps!
EDIT4: I am able to dump an empty queryset, but as soon as I add anything of value, it fails.
EDIT4: I am on Django 1.2.3
This may not be the case for everyone, but I was using Ipython notebook and having a similar issue pickling my own class.
The problem turned out to be from a reload call
from dir.my_module import my_class
reload(dir.my_module)
Removing the reload call and then re-running the import and the cell where the instance of that object was created then allowed it to be pickled.
not so elegant but perhaps it works:
add the directory of the myfile -module to os.sys.path and use only import myfile in each module where you use myfile. (remove any from segment.segmentengine.models.segment import, anywhere in your project)
According to this doc, pickling a QuerySet should be not a problem. Thus, the problem should come from other place.
Since you mentined:
EDIT2: I had a typo in the error I displayed above -- it was models.QuerySet, not models.mymodel.QuerySet that it was complaining about. There is another nuance here, which is that my models file is broken out into multiple modules, so the error is ACTUALLY:
The second error message you provided look like the same as previous one, is that what you mean?
The error message you provided looks weird. Since you are pickling "queryset.query", the error should related to the django.db.models.sql.Query class instead of the QuerySet class.
Some modules or classes may have the same name. They will override each other then cause this kind of issue. To make thing easier, I will recommend you to use "import ooo.xxx" instead of "from ooo import *".
Your could also try
import ooo.xxx as othername