Django view

Types of view in django

In django we can create view in two ways:
1.Function based view
2.Class based view

Function based view

Function based view, is like python function but it can takes a web request and can returns a web response. Here response can be HTML, image, XML, 404, redirect, etc. In every django function the first parameter is a HttpRequest object.

We have to write view function inside views.py file. You will get this files inside application. Suppose you have two application but you want to create a view function for first application. So inside first application you will see a views.py file, inside that file write the view function. You can create multiple functions in views.py file.

Here request parameter is the HttpRequest object. For better practice write request there every time. You can also use more parameters. Look here HttpRequest is a class. So to use this class we have to import the class in views.py file.
To import HttpRequest class,
from django.http import HttpResponse
After importing then start creating the functions.

After creating the view function we have to define a url of that function in the urls.py file of the project folder. For each view function you have to define a url in the urls.py file.

Let's see an example:

We have a application names myFirstApp. There in the view function we have created four functions. Then we will go to the urls.py file of project folder, there we will create urls for those functions.

Step 1:
Import HttpResponse in views.py file then create the functions.

In the image green marked area, we created the functions. In the blue marked area, you can see, we import HttpResponse. We created this function in views.py function inside myFirstApp application. You can create in multiple application but the process is same.

Step 2:

Create urls.
In the blue marked area, at first we import that applications where we created the functions. If you have multiple application and then you have to import each application here. Then in green marked area we created the urls.

Basic problem while running the django server?

Suppose you defined or created an url. When we run the django server then at first we will see a 404 error massage. To see that page of that url which we defined, then in the url of the browser, pass a url name(that we defined) at the end of the server port. By doing this you will see that page. Now if we don't want to see that error page and we directly want to see the created url page. Then we have to make that url as default url. Default url means server will open on that page. To do that we have to just create a url where the url will not have any name.

Look here the home_Func url doesn't have any name but first_func url have a name. So when we will run the server, we will see home_func. Now we will not see the error and we will see all the thing defined in home_Func function. Now if we want to see first_func the we have to copy and paste the url name of first_func in the end of server port present in the browser url. You can also make first_func as default. To do this remove the name of first_func url and give name to other urls.

Problem while creating urls from multiple application.

Suppose you have two application:
    1.myFirstApp:
      In this application you have two function:
        1.myFirstFunction
        2.mySecondFunction
    2.mySecondApp
      In this application you have two function:
        1.myThirdFunction
        2.myFourthFunction

Let's create urls:

Look to create urls we import views from both application. Now how django will know that from which views.py file which function comes.

We can solve this problem in two ways:
First method:
Give a nickname of views.py file while importing and use that nickname to create the urls.

Second Method:
Previously what we are doing is that we are importing views.py file from each application. In this method we will directly import each function present in each views.py file from each application.

How to create urls inside application?

What we did that we define functions in a application and then create a urls for those functions inside project folder urls.py file. When we are working on a small project, in that case we can use this process.But when we have a big project and inside that project if we have so many applications, in that case this method of creating urls can create problems. If you follow the previous method, the program will run but while editing the code it will create a problem. Because there will be a lot urls.This method increase the dependency of application in project.For this reason if we want to use a application for another project then the dependency can create problem. So for big project and decrease the dependency of application we shouldn't follow the previously explained method.I will recommend you to define urls inside applications because you don't that much big will be you project.

From now what we will do is that we will create or define urls inside the application.

Let's create urls inside application
Suppose you have a application:
    1.myFirstApp:
      In this application you have two function:
        1.myFirstFunction
        2.mySecondFunction

Step 1:
Create a python file inside application and give name of that file is urls. In short create a urls.py file inside application.

Step 2:
Go to the url file which you have created. Then at first, you have to import views.py and path.

Step 3:
Now we have to include this application url file inside project url file.

Before include files import include.