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Methods from a single view to different endpoints: keep APIs for HTML and for JSON separated (Django Rest Framework)

Could you help suggesting how to keep coding style organised to keep endpoints from HTML and JSON separated, in Django Rest Framework ?
In Flask I am used to keeps endpoints for serving Json, and ones for serving HTML, separated, like:
#application.route('/api/')
def api_root():
#...
return jsonify({'data' : data})
and
#application.route('/home/<string:page>/', endpoint='page_template')
#...
return render_template(template, page)
And so I could serve the APIs like:
/api/page => serve the json for the page, say for AJAX etc.
/page => serve the corresponding html page
In Django RF, I read that a ModelViewSet can serve both.
So I could keep everything in one place.
However, when I come to map views on the router, I would have all the endpoint served respect the path related my model, they would be all sub-path of /api
Could you help in advising a good coding practice to make use of ModelViewSet, and route endpoints for html separated from APIs ?
This is the example Im working on, my doubts are in comments:
from rest_framework import viewsets
from rest_framework import generics
from rest_framework.decorators import action
from rest_framework.response import Response
from .serializers import PersonSerializer
from .models import Person
class PersonViewSet( viewsets.ModelViewSet):
queryset = Person.objects.all().order_by('name')
serializer_class = PersonSerializer
# this will return last person
# I can see it registered at: 127.0.0.1:8000/api/people/last_person/
#action(detail=False)
def last_person(self, request):
queryset = Person.objects.all().order_by('timestamp').reverse()[0]
serializer = self.get_serializer(queryset)
return Response(serializer.data)
# this will return a template:
# I can see it registered at: ../api/people/greetings : I wanted at /greetings
#action(detail=False)
def greetings(self, request):
queryset = Person.objects.all().order_by('timestamp').reverse()[0]
serializer = self.get_serializer(queryset)
return render(
request,
'myapi/greetings.html',
{
'person': serializer.data
}
)
Also, please note how I am serving the method greetings: here I am repeating the queryset and serialising part. I thought to do:
def greetings(self, request):
person = self.last_person(request)
return render(
request,
'myapi/greetings.html',
{
'person': person
}
)
But it will give error, because personwould be a Response object, and could not find a way to pass it to the render.
Which could be a good coding style to avoid replicating things, and keep APIs and templates separated ?
In /myapi/url.py I am registered the endpoints like:
router = routers.DefaultRouter()
router.register(r'people', views.PersonViewSet)
app_name = 'myapi'
urlpatterns = [
path('', include(router.urls)),
]
In the main url.py, like this:
from django.urls import include
urlpatterns = [
path('admin/', admin.site.urls),
path('api/', include('myapi.urls')),
path('', include('myapi.urls')) # How to keep views for templates and for Json separated ??
]

If everything before the response phase is the same, you should not touch anything except renderers. You can provide a response in the desired format by choosing the right renderer based on user's request, precisely on the media-type -- Accept header.
For example, let's say you want to send a JSON and HTML response based on the media-type (Accept header). So when you pass (passing only one media-type to keep the example simple):
Accept: application/json it should return reponse in JSON
Accept: text/html it should return HTML response
Before moving with the implementation, let's discuss first how DRF handles renderers:
Renderers can be defined globally in settings.py as DEFAULT_RENDERER_CLASSES collection or on a per view (viewsets are technically views with the method-action mappings and associated logics) basis as renderer_classes class attribute.
The order of renderers is very important. DRF chooses the most specific renderer based on the Accept value. For more generic one or for catch-all (*/*) the first renderer that satisfies media-type is chosen.
if you use DRF's DefaultRouter for URL mappings, you can also use the format extension to filter out any renderer that does not support the passed format. For example, if you have an endpoint /foo/1/, you can add a format like /foo/1.json/. Then only the renderer classes that have format = json as an attribute will be selected (and then the final selection mentioned in the earlier point will take place only among these renderers).
So based on the above, from the API consumer, you need to pass the correct Accept header and if using DefaultRouter also better to add the format extension to do the pre-filtering on the renderers.
On the API, do:
define renderer classes in the correct order as mentioned earlier
if the consumer passes format, makes sure the renderer has the format name as an attribute
if you send the response yourself, make sure you use the Response (rest_framework.response.Response) class which passes the correct renderer context and calls the render method of the renderer to send the correct response back
If you want to send a JSON response, you can actually leverage the JSONRenderer (rest_framework.renderers.JSONRenderer) which serves the purpose perfectly. If you want to customize only a few things, you can create your own subclassing JSONRenderer.
In the case of sending an HTTP response, you can take inspiration from the TemplateHTMLRenderer (rest_framework.renderers.TemplateHTMLRenderer) or extend it to meet your needs. It has the boilerplate:
media_type = 'text/html'
format = 'html'
template_name = None
exception_template_names = [
'%(status_code)s.html',
'api_exception.html'
]
charset = 'utf-8'
and the data passed in by the serializer is already available as the template context. So you can set the template_name above (or pass in with Response if you're overriding) and add all HTML representations there. You can also override render to have more customization there if you want.
And eventually, if you feel like making a custom one yourself, the DRF doc is pretty awesome in explaining what you need to do.

Convert GET parameters to POST data on a Request object in Django REST Framework

I am in the process of rewriting the backend of an internal website from PHP to Django (using REST framework).
Both versions (PHP and Django) need to be deployed concurrently for a while, and we have a set of software tools that interact with the legacy website through a simple AJAX API. All requests are done with the GET method.
My approach so far to make requests work on both sites was to make a simple adapter app, routed to 'http://<site-name>/ajax.php' to simulate the call to the Ajax controller. Said app contains one simple function based view which retrieves data from the incoming request to determine which corresponding Django view to call on the incoming request (basically what the Ajax controller does on the PHP version).
It does work, but I encountered a problem. One of my API actions was a simple entry creation in a DB table. So I defined my DRF viewset using some generic mixins:
class MyViewSet(MyGenericViewSet, CreateModelMixin):
# ...
This adds a create action routed to POST requests on the page. Exactly what I need. Except my incoming requests are using GET method... I could write my own create action and make it accept GET requests, but in the long run, our tools will adapt to the Django API and the adapter app will no longer be needed so I would rather have "clean" view sets and models. It makes more sense to use POST for such an action.
In my adapter app view, I naively tried this:
request.method = "POST"
request.POST = request.GET
Before handing the request to the create view. As expected it did not work and I got a CSRF authentication failure message, although my adapter app view has a #csrf_exempt decorator...
I know I might be trying to fit triangle in squares here, but is there a way to make this work without rewriting my own create action ?

You can define a custom create method in your ViewSet, without overriding the original one, by utilizing the #action decorator that can accept GET requests and do the creation:
class MyViewSet(MyGenericViewSet, CreateModelMixin):
...
#action(methods=['get'], detail=False, url_path='create-from-get')
def create_from_get(self, request, *args, **kwargs):
# Do your object creation here.
You will need a Router in your urls to connect the action automatically to your urls (A SimpleRouter will most likely do).
In your urls.py:
router = SimpleRouter()
router.register('something', MyViewSet, base_name='something')
urlpatterns = [
...
path('my_api/', include(router.urls)),
...
]
Now you have an action that can create a model instance from a GET request (you need to add the logic that does that creation though) and you can access it with the following url:
your_domain/my_api/something/create-from-get
When you don't need this endpoint anymore, simply delete this part of the code and the action seizes to exist (or you can keep it for legacy reasons, that is up to you)!

With the advice from all answers pointing to creating another view, this is what I ended up doing. Inside adapter/views.py:
from rest_framework.settings import api_settings
from rest_framework.decorators import api_view, renderer_classes
from rest_framework.response import Response
from rest_framework import status
from mycoreapp.renderers import MyJSONRenderer
from myapp.views import MyViewSet
#api_view(http_method_names=["GET"])
#renderer_classes((MyJSONRenderer,))
def create_entity_from_get(request, *args, **kwargs):
"""This view exists for compatibility with the old API only.
Use 'POST' method directly to create a new entity."""
query_params_copy = request.query_params.copy()
# This is just some adjustments to make the legacy request params work with the serializer
query_params_copy["foo"] = {"name": request.query_params.get("foo", None)}
query_params_copy["bar"] = {"name": request.query_params.get("bar", None)}
serializer = MyViewSet.serializer_class(data=query_params_copy)
serializer.is_valid(raise_exception=True)
serializer.save()
try:
headers = {'Location': str(serializer.data[api_settings.URL_FIELD_NAME])}
except (TypeError, KeyError):
headers = {}
return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)
Of course I have obfuscated the names of everything specific to my project. Basically I reproduced almost exactly (except for a few tweaks to my query params) what happens in the create, perform_create and get_success_header methods of the DRF mixin CreateModelMixin in a single function based DRF view. Being just a standalone function it can sit in my adapter app views so that all legacy API code is sitting in one place only, which was my intent with this question.

You can write a method for your viewset (custom_get) which will be called when a GET call is made to your url, and call your create method from there.
class MyViewSet(MyGenericViewSet, CreateModelMixin):
...
def custom_get(self, request, *args, **kwargs):
return self.create(request, *args, **kwargs)
And in your urls.py, for your viewset, you can define that this method needs to be called on a GET call.
#urls.py
urlpatterns = [
...
url(r'^your-url/$', MyViewSet.as_view({'get': 'custom_get'}), name='url-name'),
]

As per REST architectural principles request method GET is only intended to retrieve the information. So, we should not perform a create operation with request method GET. To perform the create operation use request method POST.
Temporary Fix to your question
from rest_framework import generics, status
class CreateAPIView(generics.CreateView):
def create(self, request, *args, **kwargs):
serializer = self.get_serializer(data=request.query_params)
serializer.is_valid(raise_exception=True)
self.perform_create(serializer)
headers = self.get_success_headers(serializer.data)
return Response(
serializer.data,
status=status.HTTP_201_CREATED,
headers=headers)
def get(self, request, *args, **kwargs):
return self.create(request, *args, **kwargs)
Please refer below references for more information.
https://www.w3.org/Protocols/rfc2616/rfc2616-sec5.html
https://learnbatta.com/blog/introduction-to-restful-apis-72/

Django view that redirects to another domain

How to redirect to another domain with python django and pass additional informations?
For example i want to redirect to https://ssl.dotpay.pl/test_payment/ and give additional informations so url will look like this
https://ssl.dotpay.pl/test_payment/?id=123456&amount=123.00&description=Test
but I don't want to generate url in my view, just pass the data in json or something like that.
What is the way to do this?

this is generated url by what i meant 'ssl.dotpay.pl/test_payment/?id=123456&amount={}&description={}'.format(123.00, 'Test')
Be sure to put a protocol before your url (or at least two slashes).
This way, Django will see it as an absolute path.
From your comment it seems you redirect to ssl.dotpay.pl what will be seen as a local path rather than another domain.
This is what I came across. (See question I put on stackoverflow and answer)
So in your case, you can use the following:
class MyView(View):
def get(self, request, *args, **kwargs):
url = 'https://ssl.dotpay.pl/test_payment/'
'?id=123456&amount={}&description={}'.format(123.00, 'Test')
return HttpResponseRedirect(url)
You could also use redirect from django.shortcuts instead of HttpResponseRedirect

Assuming you are using a functional view, you could probably do something like this in your view:
from django.http import HttpResponseRedirect
def theview(request):
# your logic here
return HttpResponseRedirect(<theURL>)

Django Rest Framework for function based views

I'm having trouble getting the JSON for function based views in django. I have the below code. I basically would like the function to return either json or an html page based on the user request.
#api_view(['GET'])
#renderer_classes((JSONRenderer,TemplateHTMLRenderer,BrowsableAPIRenderer))
def meld_live_orders(request):
if request.method =='GET':
current_orders = Meld_Sales.objects.values_list('TicketNo',flat=True).distinct()
prev_orders = Meld_Order.objects.values_list('TicketNo',flat =True).distinct()
live_orders = live_order_generator(current_orders,prev_orders)
return render(request,'live_orders.html',{'live_orders':live_orders})
When i go to the url - http://localhost:8000/live-orders.json
I'm getting an error which states the below -meld_live_orders() got an unexpected keyword argument 'format'
Is this because i need to include the serializer class somewhere the same way in CBVs? Doesnt the #API_VIEW serialize the response?
i tried including format = '' in the function argument. but the problem is that it still renders html when i want it to render json.

You need to make some changes to your code.
Firstly, you need to use format_suffix_patterns in your urls if you have not defined it. This will allow us to use filename extensions on URLs thereby providing an endpoint for a given media type.
from rest_framework.urlpatterns import format_suffix_patterns
urlpatterns = [
...
]
urlpatterns = format_suffix_patterns(urlpatterns, allowed=['json', 'html']) # allow us to use '.json' and '.html' at the end of the url
Secondly. your view does not have a format parameter in the definition.
When using format_suffix_patterns, you must make sure to add the
'format' keyword argument to the corresponding views.
#api_view(['GET'])
#renderer_classes((JSONRenderer,TemplateHTMLRenderer,BrowsableAPIRenderer))
def meld_live_orders(request, format=None): # add a 'format' parameter
...
Thirdly, you need to return a DRF response and not a Django response which you are returning at the end of the view.

You must have match a format parameter in the url pattern, but in the view function there is not an argument named format. Change the view definition into:
def meld_live_orders(request, format = ""):

Is there a way to capture URL parameters with django in urls.py?

I am trying to write something elegant where I am not relying on Request object in my code. All the examples are using:
(r'^hello/(?P.*)$', 'foobar.views.hello')
but it doesn't seem like you can post to a URL like that very easily with a form. Is there a way to make that URL respond to ..../hello?name=smith

Absolutely. If your url is mapped to a function, in this case foobar.views.hello, then that function might look like this for a GET request:
def hello(request):
if request.method == "GET":
name_detail = request.GET.get("name", None)
if name_detail:
# got details
else:
# error handling if required.
Data in encoded forms, i.e. POST parameters, is available if you HTTP POST from request.POST.
You can also construct these yourself if you want, say, query parameters on a POST request. Just do this:
PARAMS = dict()
raw_qs = request.META.get('QUERY_STRING', '') # this will be the raw query string
if raw_qs:
for line in raw_qs.split("&"):
key,arg = line.split("=")
PARAMS[key] = arg
And likewise for form-encoded parameters in non POST requests, do this:
FORM_PARAMS = QueryDict(request.raw_post_data)
However, if you're trying to use forms with Django, you should definitely look at django.forms. The whole forms library will just generally make your life easier; I've never written a html form by hand using Django because this part of Django takes all the work out of it. As a quick summary, you do this:
forms.py:
class FooForm(forms.Form):
name = fields.CharField(max_length=200)
# other properties
or even this:
class FooForm(forms.ModelForm):
class Meta:
model = model_name
Then in your request, you can pass a form out to the template:
def pagewithforminit(request):
myform = FooForm()
return render_to_response('sometemplate.html', {'nameintemplate': myform},
context_instance=RequestContext(request))
And in the view that receives it:
def pagepostingto(request):
myform = FooForm(request.POST)
if myform.is_valid(): # check the fields for you:
# do something with results. if a model form, this:
myform.save()
# creates a model for you.
See also model forms. In short, I strongly recommend django.forms.

You can't catch GET parameters in a URL pattern. As you can see in django.core.handlers.base.BaseHandler.get_response, only the part of the URL that ends up in request.path_info is used to resolve an URL:
callback, callback_args, callback_kwargs = resolver.resolve(
request.path_info)
request.path_info does not contain the GET parameters. For handling those, see Ninefingers answer.