想要获取mongodb集合中所有的键名字
如：
db.things.insert( { type : ['dog', 'cat'] } );
db.things.insert( { egg : ['cat'] } );
db.things.insert( { type : [] } );
db.things.insert( { hello : [] } );
获取到所有的键名：
type, egg, hello
代码如下：
from pymongo import MongoClient
from bson import Code
def get_keys(db, collection):
# db mongodb的集合
client = MongoClient()
db = client[db]
map = Code("function() { for (var key in this) { emit(key, null); } }")
reduce = Code("function(key, stuff) { return null; }")
result = db[collection].map_reduce(map, reduce, "myresults")
return result.distinct('_id')
参考：https://stackoverflow.com/questions/2298870/get-names-of-all-keys-in-the-collection
