The Django REST framework provides many options to enable pagination. First, we will set up one of the customizable pagination styles included in the Django REST framework to include a maximum of four resources in each individual page of data.
Our RESTful Web Service uses the generic views that work with mixin classes. These classes are prepared to build paginated responses based on specific settings in the Django REST framework configuration. Hence, our RESTful Web Service will automatically take into account the pagination settings we configured, without requiring additional changes in the code.
Open the restful01/restful01/settings.py file that declares module-level variables that define the configuration of Django for the restful01 project. We will make some changes to this Django settings file. The code file for the sample is included in the hillar_django_restful_07_01 folder, in the restful01/restful01/settings.py file. Add the following lines that declare a dictionary named REST_FRAMEWORK with key-value pairs that configure the global pagination settings:
REST_FRAMEWORK = {
'DEFAULT_PAGINATION_CLASS':
'rest_framework.pagination.LimitOffsetPagination',
'PAGE_SIZE': 4
}
Save the changes and Django's development server will recognize the edits and start again with the new pagination settings enabled. The new dictionary has two string keys: 'DEFAULT_PAGINATION_CLASS' and 'PAGE_SIZE'. The value for the 'DEFAULT_PAGINATION_CLASS' key specifies a global setting with the default pagination class that the generic views will use to provide paginated responses. In this case, we will use the rest_framework.pagination.LimitOffsetPagination class that provides a limit/offset-based style.
This pagination style works with a limit parameter that indicates the maximum number of items to return and an offset that specifies the starting position of the query. The value for the PAGE_SIZE settings key specifies a global setting with the default value for the limit, also known as the page size. In this case, the value is set to 4, and therefore, the maximum number of resources returned in a single request will be four. We can specify a different limit when we perform the HTTP request by specifying the desired value in the limit query parameter. We can configure the class to have a maximum limit value in order to avoid undesired huge result sets. This way, we can make sure that the user won't be able to specify a large number for the limit value. However, we will make this specific configuration later.
Now, we will compose and send many HTTP POST requests to create nine additional drones related to the two drone categories we created: Quadcopter and Octocopter. This way, we will have a total of 11 drones (two existing drones, plus nine additional drones) to test the limit/offset pagination mechanism we have enabled:
http POST :8000/drones/ name="Need for Speed" drone_category="Quadcopter" manufacturing_date="2017-01-20T02:02:00.716312Z" has_it_competed=false
http POST :8000/drones/ name="Eclipse" drone_category="Octocopter" manufacturing_date="2017-02-18T02:02:00.716312Z" has_it_competed=false
http POST :8000/drones/ name="Gossamer Albatross" drone_category="Quadcopter" manufacturing_date="2017-03-20T02:02:00.716312Z" has_it_competed=false
http POST :8000/drones/ name="Dassault Falcon 7X" drone_category="Octocopter" manufacturing_date="2017-04-18T02:02:00.716312Z" has_it_competed=false
http POST :8000/drones/ name="Gulfstream I" drone_category="Quadcopter" manufacturing_date="2017-05-20T02:02:00.716312Z" has_it_competed=false
http POST :8000/drones/ name="RV-3" drone_category="Octocopter" manufacturing_date="2017-06-18T02:02:00.716312Z" has_it_competed=false
http POST :8000/drones/ name="Dusty" drone_category="Quadcopter" manufacturing_date="2017-07-20T02:02:00.716312Z" has_it_competed=false
http POST :8000/drones/ name="Ripslinger" drone_category="Octocopter" manufacturing_date="2017-08-18T02:02:00.716312Z" has_it_competed=false
http POST :8000/drones/ name="Skipper" drone_category="Quadcopter" manufacturing_date="2017-09-20T02:02:00.716312Z" has_it_competed=false
The following are the equivalent curl commands:
curl -iX POST -H "Content-Type: application/json" -d '{"name":"Need for Speed", "drone_category":"Quadcopter", "manufacturing_date": "2017-01-20T02:02:00.716312Z", "has_it_competed": "false"}' localhost:8000/drones/
curl -iX POST -H "Content-Type: application/json" -d '{"name":"Eclipse", "drone_category":"Octocopter", "manufacturing_date": "2017-02-20T02:02:00.716312Z", "has_it_competed": "false"}' localhost:8000/drones/
curl -iX POST -H "Content-Type: application/json" -d '{"name":"Gossamer Albatross", "drone_category":"Quadcopter", "manufacturing_date": "2017-03-20T02:02:00.716312Z", "has_it_competed": "false"}' localhost:8000/drones/
curl -iX POST -H "Content-Type: application/json" -d '{"name":"Dassault Falcon 7X", "drone_category":"Octocopter", "manufacturing_date": "2017-04-20T02:02:00.716312Z", "has_it_competed": "false"}' localhost:8000/drones/
curl -iX POST -H "Content-Type: application/json" -d '{"name":"Gulfstream I", "drone_category":"Quadcopter", "manufacturing_date": "2017-05-20T02:02:00.716312Z", "has_it_competed": "false"}' localhost:8000/drones/
curl -iX POST -H "Content-Type: application/json" -d '{"name":"RV-3", "drone_category":"Octocopter", "manufacturing_date": "2017-06-20T02:02:00.716312Z", "has_it_competed": "false"}' localhost:8000/drones/
curl -iX POST -H "Content-Type: application/json" -d '{"name":"Dusty", "drone_category":"Quadcopter", "manufacturing_date": "2017-07-20T02:02:00.716312Z", "has_it_competed": "false"}' localhost:8000/drones/
curl -iX POST -H "Content-Type: application/json" -d '{"name":"Ripslinger", "drone_category":"Octocopter", "manufacturing_date": "2017-08-20T02:02:00.716312Z", "has_it_competed": "false"}' localhost:8000/drones/
curl -iX POST -H "Content-Type: application/json" -d '{"name":"Skipper", "drone_category":"Quadcopter", "manufacturing_date": "2017-09-20T02:02:00.716312Z", "has_it_competed": "false"}' localhost:8000/drones/
The previous commands will compose and send nine HTTP POST requests with the specified JSON key-value pairs. The requests specify /drones/, and therefore, they will match the '^drones/$' regular expression and run the post method for the views.DroneList class-based view.