I am new to Django and scratching my head with the following question
how do I know which function is run in specific processes?
for example in below view, retrieve function is executed. I flipped the documentation, however, could not find anything named retrieve to overwrite
class ProfileRetrieveAPIView(RetrieveAPIView):
serializer_class = ProfileSerializer
def retrieve(self, request, username, *args, **kwargs):
print("hey yo i am running 01")
try:
profile = Profile.objects.select_related('user').get(
user__username=username
)
except Profile.DoesNotExist:
raise
serializer = self.serializer_class(profile)
return Response(serializer.data)
In general the generic views in Django Rest Framework are made by inheriting from various mixins. It is also documented which mixin a view is inheriting from. For example the documentation for RetrieveAPIView which you use is as follows:
Used for read-only endpoints to represent a single model instance.
Provides a get method handler.
Extends:
GenericAPIView,
RetrieveModelMixin
So you can override get here if needed (it actually calls the retrieve method here). If you further follow the link for RetrieveModelMixin you will see that it's documentation has this line:
Provides a .retrieve(request, *args, **kwargs) method, that implements
returning an existing model instance in a response.
Here we can see it mentions that it provides a retrieve method. So you just need to check the documentation for the super classes for a respective class if you want to know what method is used by it.
Note: If all else fails when searching the documentation consider simply looking at it's the source code on GitHub or in your own IDE.
;)
According to DRF documentation, there is a default mapping the views and the router:
list is for GET on a list of objects, like /users/
retrieve is for GET on a single object, like /users/3/
create is for POST on a non-detailed endpoint, like /users/
update is for PUT on a detailed endpoint, like /users/3/
partial_update is for PATCH on a detailed endpoint, like /users/3/
destroy is for DELETE on a detailed endpoint, like /users/3/
Those are the expected/standard mappings within DRF views and viewsets
You can view some examples here: https://www.django-rest-framework.org/api-guide/generic-views/#mixins
Related
I am subclassing the DecimalField class from Django RestFramework and need to access context. Formatting for decimal fields includes settings that are user-selectable, so I need to access the user object (which, I assume, should be inside context) inside the to_representation() method.
Via debug, I've looked at all properties of self inside my CustomDecimalField class, but, of course, I can't see class methods, so I don't know if there's an appropriate "get" method to get context. I've tried self.context (as a property), self.get_context(), and self.getcontext(), but none worked.
I found this announcement re: require_context:
https://www.django-rest-framework.org/community/3.11-announcement/
...but it seems to be valid only for validation and default value methods.
This seems like such a simple thing; hard to believe it is so difficult.
You have to manually set the user inside the context. So, in your view:
serializer = YourSerializer(your_data, context={'user': request.user})
And you will then be able to access it in your to_representation() method:
def to_representation(self, instance):
user = self.context.get("user")
Please see the documentation for more information.
Django REST Framework ModelViewset offers the standard methods to update / create / retrieve objects. I would like to overwrite these method in the sense that they should keep their original behaviour as given by ModelViewSet, but just add to that a check in the beginning if the incoming request contains a certain query parameter. How can I do that?
Eg. I would like to have
class MyRessourceViewSet(viewsets.ModelViewSet):
queryset = MyRessource.objects.all()
serializer_class = MyRessourceSerializer
def create(self, request):
# Check if "key" query param is in request
if "key" in self.request.data:
create(request) # <<-- HERE call the "default" create method.
To call the default behavior, you can do super().create(request). Often when overriding a method, we add behavior before or after doing this.
Note that "decorate" has a technical meaning in Python and this isn't it. If you are interested in learning more, you can google something like "python decorator".
I am creating an app with a rest API that should return values for instances of objects based on the url given. Right now I have the API working using ModelViewSets of my objects for the API.
For example I have three objects, user, transactions, and goals.
As it stands I can go to /mysite/api/users and return a list of all users
I can also go to /mysite/api/users/1 to return just the user with the id '1'.
I can do something similar with transactions and goals.
What I'm looking to do is go to url /mysite/api/users/1/transaction/1/goal
to find the goal associated with the transaction for that user.
I've been scouring tutorials and am not sure what the right question is to ask in order to find something useful to learn how to do this. What is the correct way to go about setting up my rest api like this?
If I understand correctly, you want to create nested ressources.
If you are using Viewsets, then the ExtendedRouter class of the drf-extensions package will allow you to achieve this.
Drf-extensions documentation about this feature: https://chibisov.github.io/drf-extensions/docs/#nested-routes
There is also this module, who also offer the same features.
You can either use url params or query params to solve your issue. I will explain the URL params solution here,
serializers.py
#Write a Goal Serializer
urls.py
#change the URL according to your environment
url(r'^users/(?P<uid>[0-9]+)/transaction/(?P<tid>[0-9]+)/goal/$', GoalViewSet.as_view({'get': 'user_transaction_goal',}), name='user-transaction-goal'),
views.py
class GoalViewSet(viewsets.ModelViewSet):
permission_classes = [IsAuthenticated]
queryset = Goal.objects.all()
def user_transaction_goal(self, request, uid, tid):
#assuming user is FK in transaction and transaction is a FK in goal
#modify the filter rule according to your model design
goals = Goal.objects.filter(transaction=tid, transaction__user=uid)
serializer = GoalSerializer(goals, many=False)
return Response(serializer.data)
As #clement mentioned you can also use plugins to handle this situation.
I'm trying to manage my REST API like that :
http://xxx/users/userid[0-9]+/projects/projectid[0-9]+/tasks/taskid[0-9]+/
So I can access the JSON easily in my website. But, the thing is, I defined my view classes using the REST framework generic views. For example, here is my UserDetail view :
class UserDetail(generics.RetrieveUpdateDestroyAPIView):
queryset = User.objects.all()
serializer_class = UserSerializer
But of course I don't want all my users to be displayed, I just want my user with the ID userid to be displayed. I don't really know how to do it, I tried
queryset = User.objects.filter(id=userid)
but of course userid is not defined... Any help please ?
Edit : just to clarify, here is the url that leads to this view :
url(r'^users/(?P<pku>[0-9]+)/$', views.UserDetail.as_view(
), name='user-detail'),
First of all, If you want to use class based views, you should read some more about them. They are thoroughly explained on Django's docs and you can read about the specific generics of the framework you're using on the REST framework docs too. I'm not saying that you haven't read those, just that you seem to be missing some basic concepts that are explained there.
Now, to the problem at hand, if you look at the doc's of the generic view you're extending, you can see that it represents the endpoints for a single instance, meaning that it won't act on all your model's instances (as you seem to assume).
Also, you can see that this view is built on top of a series of other classes, the more critical one being GenericAPIView. On there you can see two things:
The queryset class field in this context is meant for filtering the posible instances you can manipulate, not obtaining the specific instance described on your url.
The lookup_field is the field that defines which attribute from your model will be used for getting the actual instance. You should define this field to whatever field you're going to use on your url to identify your object (generally it's pk). It's also important to note that the url should include a keyword argument corresponding to this value.
Internally, the view will take care of calling the get_object method, which usese the lookup_field value to find the specific model, and then feed that object to the serializer and return the result back to the client.
DISCLAIMER: I've never used Django REST framework, I put this answer togheter by reading the relevants docs and based on my experience.
I guess you need this:
Resolve function (django 1.4)
Then in your view class method you can do:
temp1, args, kwargs = resolve(self.request.path)
I want to overwrite the custom objects model manager to only return objects a specific user created. Admin users should still return all objects using the objects model manager.
Now I have found an approach that could work. They propose to create your own middleware looking like this:
#### myproject/middleware/threadlocals.py
try:
from threading import local
except ImportError:
# Python 2.3 compatibility
from django.utils._threading_local import local
_thread_locals = local()
def get_current_user():
return getattr(_thread_locals, 'user', None)
class ThreadLocals(object):
"""Middleware that gets various objects from the
request object and saves them in thread local storage."""
def process_request(self, request):
_thread_locals.user = getattr(request, 'user', None)
#### end
And in the Custom manager you could call the get_current_user() method to return only objects a specific user created.
class UserContactManager(models.Manager):
def get_query_set(self):
return super(UserContactManager, self).get_query_set().filter(creator=get_current_user())
Is this a good approach to this use-case? Will this work? Or is this like "using a sledgehammer to crack a nut" ? ;-)
Just using:
Contact.objects.filter(created_by= user)
in each view doesn`t look very neat to me.
EDIT Do not use this middleware approach !!!
use the approach stated by Jack M. below
After a while of testing this approach behaved pretty strange and with this approach you mix up a global-state with a current request.
Use the approach presented below. It is really easy and no need to hack around with the middleware.
create a custom manager in your model with a function that expects the current user or any other user as an input.
#in your models.py
class HourRecordManager(models.Manager):
def for_user(self, user):
return self.get_query_set().filter(created_by=user)
class HourRecord(models.Model):
#Managers
objects = HourRecordManager()
#in vour view you can call the manager like this and get returned only the objects from the currently logged-in user.
hr_set = HourRecord.objects.for_user(request.user)
See also this discussion about the middelware approach.
One way to handle this would be to create a new method instead of redefining get_query_set. Something along the lines of:
class UserContactManager(models.Manager):
def for_user(self, user):
return super(UserContactManager, self).get_query_set().filter(creator=user)
class UserContact(models.Model):
[...]
objects = UserContactManager()
This allows your view to look like this:
contacts = Contact.objects.for_user(request.user)
This should help keep your view simple, and because you would be using Django's built in features, it isn't likely to break in the future.
It seems necessary to use the middleware to store the user information.
However, I'd rather not modify the default ModelManager objects, but hook it upto a different manager, that I will use in the code, say in your case user_objects instead of objects.
Since you will use this only within views that are #login_required you dont need all the complex error handling in the Middleware.
Just my 2ยข.
Or even simpler and use foreign key to retrieve queryset.
If you have model like that
class HourRecord(models.Model):
created_by = ForeignKey(get_user_model(), related_name='hour_records')
You can query HourRecords in a view by user with simply:
request.user.hour_records.all()