preamble
We have tens of millions of pieces of data in our database that need to be displayed, and we can't just read them all out of the database.
Because this puts a huge strain on memory and can easily overflow it, we want to fetch little by little.
Similarly, the same applies to the display, where we are bound to paginate the data.
In this article, we will talk about the three types of paging that DRF provides us with.
global configuration
REST_FRAMEWORK = {
# Effective for all pagers, but low priority
'PAGE_SIZE': 5, # 5 data per page
}
We start by preparing the data for testing paging and the serialization class
data sheet
from import models class Test(): """Data table for testing paging""" name = (max_length=64)
Generate table records:
# Calling Django environments in Python scripts
import os
if __name__ == '__main__':
# Execute directly after changing the following '' to the corresponding name of the project to generate the record.
('DJANGO_SETTINGS_MODULE', > '')
import django
()
from import Test # Import data tables
[(name="Flowering Bones%s" % str(i)) for i in range(100)]
serialized class (computing)
from rest_framework.serializers import ModelSerializer
from import Test # Import data tables
class TestSerializer(ModelSerializer):
"""Serialization class for testing paging"""
class Meta:
model = Test
fields = '__all__'
The first PageNumberPagination checks the nth page and displays n pieces of data per page.
Step 1 Pager Configuration File
from rest_framework import pagination class PageNumberPagination(): """Look up page n, displaying n data per page.""" page_size = 10 # Specify how many pieces of data to display per page page_size_query_param = 'size' # Parameters for the number of bars per page in the URL parameters page_query_param = 'page' # Parameters for page numbers in URLs max_page_size = None # Maximum number of data per page
Step 2 View File
from rest_framework.response import Response
from rest_framework.views import APIView
from rest_framework.serializers import ModelSerializer
from import Test # Import data tables
from blog import pagination # Import the above paging configuration
class Test01View(APIView):
def get(self, request):
queryset = ()
# 1. Instantiate the pager object
page_obj = ()
# 2. Use your own configured pager to call the paging method for paging
page_data = page_obj.paginate_queryset(queryset, request)
# 3. Serialize our paged data.
ser_obj = TestSerializer(page_data, many=True)
# 4. Return data
# return Response(ser_obj.data)
# 4. return to previous/next linked page
return page_obj.get_paginated_response(ser_obj.data)
Step 3 Access testing
As shown above, after specifying page=10&size=5, the corresponding data is returned.
***
Second LimitOffsetPagination At the nth position, look backward n pieces of data
Step 1 Pager Configuration File
from rest_framework import pagination class LimitOffsetPagination(): """At the nth position, look up n pieces of data backward.""" default_limit = 1 # Specify the default number of items to look up limit_query_param = 'limit' # Parameters in the URL that specify how many pieces of data to look up offset_query_param = 'offset' # Parameters in the URL that specify which data to start looking up from max_limit = 999 # Maximum number of data to be displayed
Step 2 View File
from rest_framework.response import Response
from rest_framework.views import APIView
from rest_framework.serializers import ModelSerializer
from import Test # Import data tables
from import LimitOffsetPagination # Import the above paging configuration
class Test02View(APIView):
def get(self, request):
queryset = ()
# 1. Instantiate the pager object
page_obj = LimitOffsetPagination()
# 2. Use your own configured pager to call the paging method for paging
page_data = page_obj.paginate_queryset(queryset, request)
# 3. Serialize our paged data.
ser_obj = TestSerializer(page_data, many=True)
# 4. Return data
# return Response(ser_obj.data)
# 4. return to previous/next linked page
return page_obj.get_paginated_response(ser_obj.data)
Step 3 Access testing
***
Third CursorPagination Encrypted Cursor Pagination
Step 1 Pager Configuration File
from rest_framework import pagination class CursorPagination(): """Pagination of encrypted cursors""" cursor_query_param = 'cursor' # Cursor (this is an encrypted cursor) # ordering = '-id' # Fetch data from back to front ordering = 'id' page_size = 1 # Number of articles per page
Step 2 View File
from rest_framework.response import Response
from rest_framework.views import APIView
from rest_framework.serializers import ModelSerializer
from import Test # Import data tables
from import CursorPagination # Import the above paging configuration
class Test03View(APIView):
def get(self, request):
queryset = ()
# 1. Instantiate the pager object
page_obj = CursorPagination()
# 2. Use your own configured pager to call the paging method for paging
page_data = page_obj.paginate_queryset(queryset, request)
# 3. Serialize our paged data.
ser_obj = TestSerializer(page_data, many=True)
# 4. Return data
# return Response(ser_obj.data)
# 4. return to previous/next linked page
return page_obj.get_paginated_response(ser_obj.data)
Okay, open your browser and test it.
Pages with previous/next buttons can also be generated using the DRF view system.
from rest_framework.viewsets import ModelViewSet class Test04View(ModelViewSet): queryset = () serializer_class = TestSerializer pagination_class = CursorPagination # Specifying the Paging Configurator
Below:
is ok.
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