增加通用分页函数和对应的测试

oj/settings.py

@@ -47,6 +47,7 @@ INSTALLED_APPS = (
     'django.contrib.staticfiles',
 
     'account',
+    'utils',
 
     'rest_framework',
     'rest_framework_swagger',

utils/shortcuts.py

@@ -1,4 +1,7 @@
 # coding=utf-8
+from django.core.paginator import Paginator
+
+from rest_framework import pagination
 from rest_framework.response import Response
 
 
@@ -11,4 +14,48 @@ def serializer_invalid_response(serializer):
 
 
 def success_response(data):
-    return Response(data={"code": 0, "data": data})
+    return Response(data={"code": 0, "data": data})
+
+
+def paginate(request, query_set, object_serializer):
+    """
+    用于分页的函数
+    :param query_set 数据库查询结果
+    :param object_serializer: 序列化单个object的serializer
+    :return response
+    """
+    need_paginate = request.GET.get("paging", None)
+    # 如果请求的参数里面没有paging=true的话 就返回全部数据
+    if need_paginate != "true":
+        return success_response(data=object_serializer(query_set, many=True).data)
+
+    page_size = request.GET.get("page_size", None)
+    if not page_size:
+        return error_response(u"参数错误")
+
+    try:
+        page_size = int(page_size)
+    except Exception:
+        return error_response(u"参数错误")
+
+    paginator = Paginator(query_set, page_size)
+    page = request.GET.get("page", None)
+
+    try:
+        current_page = paginator.page(page)
+    except Exception:
+        return error_response(u"参数错误")
+
+    data = {"results": object_serializer(current_page, many=True).data, "previous_page": None, "next_page": None}
+
+    try:
+        data["previous_page"] = current_page.previous_page_number()
+    except Exception:
+        pass
+
+    try:
+        data["next_page"] = current_page.next_page_number()
+    except Exception:
+        pass
+
+    return success_response(data)

utils/test_urls.py

@@ -0,0 +1,9 @@
+# coding=utf-8
+from django.conf.urls import include, url
+
+
+
+urlpatterns = [
+    url(r'^paginate_test/$', "utils.tests.pagination_test_func"),
+]
+

utils/tests.py

@@ -0,0 +1,64 @@
+# coding=utf-8
+from rest_framework.test import APIClient, APITestCase
+from rest_framework import serializers
+from rest_framework.decorators import api_view
+
+from account.models import User
+from .shortcuts import paginate
+
+
+class PaginationTestSerialiser(serializers.Serializer):
+    username = serializers.CharField(max_length=100)
+
+
+@api_view(["GET"])
+def pagination_test_func(request):
+    return paginate(request, User.objects.all(), PaginationTestSerialiser)
+
+
+class PaginatorTest(APITestCase):
+    urls = "utils.test_urls"
+
+    def setUp(self):
+        self.client = APIClient()
+        self.url = "/paginate_test/"
+        User.objects.create(username="test1")
+        User.objects.create(username="test2")
+
+    def test_no_paginate(self):
+        response = self.client.get(self.url)
+        self.assertEqual(response.data["code"], 0)
+        self.assertNotIn("next_page", response.data["data"])
+        self.assertNotIn("previous_page", response.data["data"])
+
+    def test_error_parameter(self):
+        response = self.client.get(self.url + "?paging=true")
+        self.assertEqual(response.data, {"code": 1, "data": u"参数错误"})
+
+        response = self.client.get(self.url + "?paging=true&limit=-1")
+        self.assertEqual(response.data, {"code": 1, "data": u"参数错误"})
+
+        response = self.client.get(self.url + "?paging=true&limit=aa")
+        self.assertEqual(response.data, {"code": 1, "data": u"参数错误"})
+
+        response = self.client.get(self.url + "?paging=true&limit=1&page_size=1&page=-1")
+        self.assertEqual(response.data, {"code": 1, "data": u"参数错误"})
+
+        response = self.client.get(self.url + "?paging=true&limit=1&page_size=aaa&page=1")
+        self.assertEqual(response.data, {"code": 1, "data": u"参数错误"})
+
+        response = self.client.get(self.url + "?paging=true&limit=1&page_size=1&page=aaa")
+        self.assertEqual(response.data, {"code": 1, "data": u"参数错误"})
+
+    def test_correct_paginate(self):
+        response = self.client.get(self.url + "?paging=true&limit=1&page_size=1&page=1")
+        self.assertEqual(response.data["code"], 0)
+        self.assertEqual(response.data["data"]["previous_page"], None)
+        self.assertEqual(response.data["data"]["next_page"], 2)
+        self.assertEqual(len(response.data["data"]["results"]), 1)
+
+        response = self.client.get(self.url + "?paging=true&limit=1&page_size=2&page=1")
+        self.assertEqual(response.data["code"], 0)
+        self.assertEqual(response.data["data"]["previous_page"], None)
+        self.assertEqual(response.data["data"]["next_page"], None)
+        self.assertEqual(len(response.data["data"]["results"]), 2)