django原生sql

参考：http://www.jb51.net/article/128257.htm

coding=utf-8

from django.core.paginator import Paginator

def paginator(data_list, per_page, page_no):
"""封装Django分页"""
pages = Paginator(data_list, per_page)

# 防止超出页数
if not page_no > 0:
page_no = 1
if page_no > pages.num_pages:
page_no = pages.num_pages

p = pages.page(page_no) # 获取本页数据

data = dict() # 获取分页信息
data['count'] = pages.count
data['page_num'] = pages.num_pages
data['per_page'] = per_page
data['current'] = page_no
data['start_index'] = p.start_index() - 1

return p.object_list, page_no, data

class QueryWrapper(object):
"""查询集包装器。实现django Paginator需要的必要方法，实现和query一样使用Paginator分页"""

def init(self, sql, params=None, db="default"):
"""
:param sql: sql语句
:param params: sql语句的params参数
:param db: 数据库名称（Django配置）
"""
self.db = db
self.sql = sql
self.params = params

def count(self):
"""计算总页数"""
sql = """select count(*) from (%s) _count""" % self.sql
# sql封装方法请参考https://my.oschina.net/watcher/blog/1573503
return fetchone_sql((sql, self.params), db=self.db, flat=True) # 返回总页数

def getslice(self, x, y):
""" self.__getslice(x, y) = self[x:y]"""
sql = self.sql + ' LIMIT {start}, {num}'.format(start=x, num=y - x)
# sql封装方法请参考https://my.oschina.net/watcher/blog/1573503
return fetchall_to_dict((sql, self.params), db=self.db) # 字典列表形式返回

def demo_orm():
"""使用Django的ORM分页"""
# 示例：查询status=1的用户分页，每页10条，取第2页数据（假设数据量足够）
status = 1
per_page = 10
page_no = 2

# 使用Django的ORM
from django.contrib.auth.models import User

query = User.objects.filter(status=status).values("id", "username", "first_name")
one_page_data_list, page_no, page_data = paginator(query, per_page, page_no)
# one_page_data_list 即为第二页数据，例如：[{"id": 1, "username": "111", "first_name": "aaa"}]
print one_page_data_list

def demo_raw():
"""使用原生sql实现相同分页"""
# 示例：查询status=1的用户分页，每页10条，取第2页数据（假设数据量足够）
status = 1
per_page = 10
page_no = 2

sql = "select id, username, first_name from auth_user where status=%(status)s"
params = {"status": status} # 使用params防止sql注入
query = QueryWrapper(sql, params, "default")
one_page_data_list, page_no, page_data = paginator(query, per_page, page_no)
# one_page_data_list 同ORM获取数据一样
print one_page_data_list

if name == "main":
demo_orm()
demo_raw()