with open ('文件名.txt', 'wb') as f:
#接下来可实现提取想要的字段内的数据
for item in collection.find({}, {"Summary":1,"Manual":1,"Claim":1,"_id":0}):
if item.has_key('Summary') and item['Summary']:
f.write(item['Summary'])
if item.has_key('Manual') and item['Manual']:
f.write(item['Manual'])
if item.has_key('Claim') and item['Claim']:
f.write(item['Claim'])
f.write('\n')