Dal介绍2：自动分页功能
2015-06-12 12:54
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上一篇文章介绍了Dal的结构和基本方法。本文主要分析缓存+db的分页方法。
.find(query,fields)
if sort:
'''排序'''
if isinstance(sort, tuple):
cursor = cursor.sort(*sort)
else:
cursor = cursor.sort(sort)
sorted_id_result = list(cursor)
for r in sorted_id_result:
r["_id"] = str(r.get("_id"))
'''获取排序的分数'''
if sort:
score = r.get(sort_field, 0.0)
else:
score = 0
if score:
try:
score = float(score)
except ValueError:
score = 0
r[sort_field] = score
'''生成排序分数的列表'''
z_id_score_list = [(r.get("_id"),0.0 if not sort else r.get(sort_field)) for r in sorted_id_result]
'''添加到redis的sortedset'''
self.redis_proxy.strict_pipeline_zadd(key, z_id_score_list)
'''设置缓存时间'''
self.get_redis().expire(key, cache_time)
if cache_kw:
self.cacheKeyword(key,query,cache_kw)
return sorted_id_result
find_by_page：分页查询
@ctime(NAME)
"""
table：mongodb的表名
prefix：缓存前缀
query：查询条件，dict类型
cache：是否使用缓存
cache_time：缓存时间
sort：排序条件
criteria：查询的字段
page：页数
count：每页的数量
cache_kw：关联的缓存key
pack：缓存value是否使用msgpack
"""
def find_by_page(self, table, prefix="", query={}, cache_time=43200, sort=None, page=1, count=20, cache_kw=None, criteria=None):
result = []
total = 0
page_count = 0
current_count = 0
try:
sorted_id_result = None
'''生成以pagecache_table开头的缓存key'''
key = self.redis_proxy.generateKey(table, prefix, query, sort, name="pagecache", criteria=criteria)
start, stop = self.get_range_by_page(page, count)
'''检查缓存的key是否存在'''
if self.redis_proxy.exists(key):
'''获取总数'''
total = self.redis_proxy.strict_zcard(key)
esc = True
if sort and len(sort) > 1 and sort[1] < 0:
esc = False
if esc:
'''升序获取缓存value'''
sorted_id_result = self.redis_proxy.strict_zrange(key, start, stop, prefix)
else:
'''降序获取缓存value'''
sorted_id_result = self.redis_proxy.strict_zrevrange(key, start, stop, prefix)
else:
'''重新从db加载分页数据'''
sorted_id_result = self.load_page_data(table, prefix, query, cache_time, sort, cache_kw=cache_kw, criteria=criteria)
if cache_kw:
'''关联缓存'''
self.cacheKeyword(key,query,cache_kw)
total = len(sorted_id_result)
if count > 0:
'''取出主键_id'''
sorted_id_result = [r.get("_id") for r in sorted_id_result][start:stop+1]
else:
sorted_id_result = [r.get("_id") for r in sorted_id_result]
current_count = len(sorted_id_result)
if self.debug:
self.logger.debug('[Dal.find_by_page] table=%s,prefix=%s,query=%s,sort=%s,page=%s,count=%s,criteria=%s' %(table,prefix,query,sort,page,count,criteria))
if not sorted_id_result:
return result,page_count,current_count,total
page_count = len(sorted_id_result)
for _id in sorted_id_result:
'''根据_id查询记录'''
item = self.find_one(table, query={"_id":ObjectId(_id)},criteria=criteria,cache=True,cache_time=300)
'''生成find_one的key'''
find_one_key=self.redis_proxy.generateKey(table, "find_one",{"_id":_id},criteria=criteria,pack=True)
'''添加到关联缓存的集合'''
self.cacheKeyword(find_one_key,{},cache_kw,prefix="")
if item:
result.append(item)
return result,page_count,current_count,total
except Exception, e:
self.logger.error('[Dal.find_by_page] error %s, bt: %s' %(e, traceback.format_exc()))
return result,page_count,current_count,totalload_page_data：重新加载分页数据
@ctime(NAME)
def load_page_data(self, table, prefix="", query={}, cache_time=43200, sort=None, cache_kw=None, criteria=None):
'''生成缓存key'''
key = self.redis_proxy.generateKey(table, prefix, query, sort, name="pagecache", criteria=criteria, pack=True)
fields = {"_id":1}
if sort:
fields[sort[0]] = 1
if sort:
sort_field =sort[0]
else:
sort_field = "sort_field"
'''查询db'''
cursor = self.get_mongodb()