Capturing url parameters in request.GET
I am currently defining regular expressions in order to capture parameters in a url, as described in the tutorial. How do I access parameters from the url as part the HttpRequest object? My HttpRequest.GET currently returns an empty QueryDict object. I'd like to learn how to do this without a library so I can get to know Django better.
When url is like:
Then you would use
q is the parameter you want, And
'' is the default value if
q isn’t found.
However, if you are instead just configuring your
URLconf, Then your captures from the
regex are passed to the function as arguments (or named arguments).
Then in your
views.py you would have
def profile_page(request, username): # Rest of the method
To clarify camflan’s explanation, let’s suppose you have
- the rule
- a in incoming request for
The URL dispatcher rule will catch parts of the URL path (here
"user/thaiyoshi/") and pass them to the view function along with the request object.
The query string (here
message=Hi) is parsed and parameters are stored as a
request.GET. No further matching or processing for HTTP GET parameters is done.
This view function would use both parts extracted from the URL path and a query parameter:
def profile_page(request, username=None): user = User.objects.get(username=username) message = request.GET.get('message')
As a side note, you’ll find the request method (in this case
"GET", and for submitted forms usually
request.method. In some cases it’s useful to check that it matches what you’re expecting.
Update: When deciding whether to use the URL path or the query parameters for passing information, the following may help:
- use the URL path for uniquely identifying resources, e.g.
- use query parameters for changing the way the resource is displayed, e.g.
- to make human friendly URLs, avoid using ID numbers and use e.g. dates, categories and/or slugs:
def some_view(request, *args, **kwargs): if kwargs.get('q', None): # Do something here ..
I would like to share a tip that may save you some time.
If you plan to use something like this in your
Which basically means
www.example.com/<username>. Be sure to place it at the end of your URL entries, because otherwise, it is prone to cause conflicts with the URL entries that follow below, i.e. accessing one of them will give you the nice error:
User matching query does not exist.
I’ve just experienced it myself; hope it helps!
For situations where you only have the
request object you can use
You have two common ways to do that in case your url looks like that:
If specific key is mandatory you can use:
key_a = request.GET['a']
This will return a value of
a if key exists and an Exception if not.
If your keys are optional:
You can try that without any argument this will not crash.
So you can wrap it with
try: except: and return
HttpResponseBadRequest() in example.
This is a simple way to make your code less complex, without using special Exceptions handling.
I’d like to add some option of myself, here. Someone would wonder how to set path in urls.py, such as
so that we could invoke query.
The fact is that it is NOT necessary to set such a route in urls.py. What you need to set is just the route in urls.py
urlpatterns = [ path('domain/search/', views.CityListView.as_view()), ]
and when you input http://servername:port/domain/search/?q=CA. The query part ‘?q=CA’ will be automatically reserved in the hash table which you can reference though
Here is an example (views.py)
class CityListView(generics.ListAPIView): serializer_class = CityNameSerializer def get_queryset(self): if self.request.method == 'GET': queryset = City.objects.all() state_name = self.request.GET.get('q', None) if state_name is not None: queryset = queryset.filter(state__name=state_name) return queryset
In addition, when you write query string in Url
Do not wrap query string in quotes e.g
This is not exactly what you asked for, but this snippet is helpful for managing
These queries are currently done in two ways. If you want to access the query parameters (GET) you can query the following:
request.query_params.get('status', None) => 1
If you want to access the parameters passed by POST, you need to access this way:
Accessing the dictionary (QueryDict) with ‘get()’, you can set a default value. In the cases above, if ‘status’ or ‘role’ are not informed, the values are None.
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