Django Web Framework[Part-6]
Let’s talk about requests and Urls in Web Development and sync with Django framework. 🍀
Request and Response Objects
A web application works on the principle of a request-response cycle in a client-server architecture, following the HTTP protocol.
Generally, a browser sends the request in the form of a URL. The web application forms a suitable response to the data contained in the request.
Django handles the request and response with the help of HttpRequest and HttpResponse classes in the django.http module.
Django obtains the HttpRequest object from the context provided by the server.
As a client request is received, Django’s URL dispatcher mechanism invokes a view that matches the URL pattern and passes this HTTPRequest object as the first argument so that all the request metadata is available to the view for processing.
HttpRequest Object
The view logic uses this attribute to identify how the client has approached the server. A browser submits its request using any HTTP methods or verbs — POST, GET, DELETE, and PUT.
Inside the view function, different conditional blocks may be executed depending on the value of the method attribute. For example:
if request.method == 'GET':
do_something()
elif request.method == 'POST':
do_something_else() According to the REST(Representational State Transfer) principle, the POST method creates a new resource on the server.
To fetch one or more resources from the server, the GET method is used. Similarly, the PUT method is for updating an existing resource, and the DELETE method is used to remove a resource from the server.
request.GET and request.POST
The attributes return a dictionary-like object containing GET and POST parameters, respectively.
request.COOKIES
Along with the parameters, the browser also packs the request objects with cookies inserted by the server’s previous interactions. It is a dictionary of string keys and values.
request.FILES
When the user uploads one or more files with a multipart form, they are present in this attribute in the form of UploadedFile objects. By appropriate logic in the view, these uploaded files are saved in the designated folder on the server.
request.user
The request object also contains information about the current user. This attribute is an object of django.contrib.auth.models.User class. However, if the user is unauthenticated, it returns AnonymousUser. Inside the view, you can lay down separated separate logic for either of them.
if request.user.is_authenticated():
# Do something for logged-in users.
else:
# Do something for anonymous users. request.has_key()
This is a method available to the request object. It helps check whether the GET or POST parameter dictionary has a value for the given key.
Unlike the HttpRequest object, which is supplied by the server’s context, the response object of HttpResponse class is instantiated inside the view function before it is returned to the client. For example:
Although it is possible to render a hardcoded HTML string as the response, Django offers a better alternative to render a template web page.
from django.http import HttpResponse
from django.template import loader
def index(request):
template = loader.get_template('demoapp/index.html')
context={}
return HttpResponse(template.render(context, request)) You can pack additional headers or cookies in the response object.
HttpResponseObject
Some of the main attributes and methods of the HttpResponse object are:
- status_code: returns the HTTP status code corresponding to the response
- content: returns the byte string of the response.
- __getitem__(): method that returns the value of a header
- __setitem__(): method used to add a header
- write(): This method creates a file-like object.
The following example demonstrates the attributes of the request and response objects. Add the following view function in views.py of the Django app.
from django.http import HttpResponse
def index(request):
path = request.path
method = request.method
content='''
<center><h2>Testing Django Request Response Objects</h2>
<p>Request path : " {}</p>
<p>Request Method :{}</p></center>
'''.format(path, method)
return HttpResponse(content) Start the server and check the response for http://localhost:8000/demo/ as the URL.
What’s Next
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I will sum up few more topics which I found interesting to look at. Let’s get learning🍀!
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