Difference between revisions of "Sort"
From NoSQLZoo
| Line 26: | Line 26: | ||
<div class=q data-lang="py3">Sort all the documents in world by continent descending, then name ascending. Show only name and continent. | <div class=q data-lang="py3">Sort all the documents in world by continent descending, then name ascending. Show only name and continent. | ||
<pre class=def> | <pre class=def> | ||
| − | + | pp.pprint(list( | |
| − | + | db.world.find({},{"name":1,"continent":1,"_id":0}).sort([("continent",-1),("name",1)]): | |
| + | )) | ||
</pre> | </pre> | ||
</div> | </div> | ||
Revision as of 14:51, 27 July 2015
#ENCODING
import io
import sys
sys.stdout = io.TextIOWrapper(sys.stdout.buffer, encoding='utf-16')
#MONGO
from pymongo import MongoClient
client = MongoClient()
client.progzoo.authenticate('scott','tiger')
db = client['progzoo']
#PRETTY
import pprint
pp = pprint.PrettyPrinter(indent=4)
#CODE
from bson.code import Code
sort() is a cursor method that orders the results of a query.
The aggregation framework provides the $sort operator, and map_reduce takes sort as a parameter that is applied to the input documents.
The syntax for sort() is sort(<field>:<value>) where 1 indicates ascending and -1 indicates descending.
The order in which fields are specified dictates which fields are sorted first.
Python does not store key order for dicts, so instead of the mongo shell {<field1>:<value>,<field2>:<value>} use [(<field1>,<value>), (<field2>,<value>)]
Sort all the documents in world by continent descending, then name ascending. Show only name and continent.
pp.pprint(list(
db.world.find({},{"name":1,"continent":1,"_id":0}).sort([("continent",-1),("name",1)]):
))