Difference between revisions of "Sort"

Revision as of 15:22, 3 December 2015

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Sort

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.

db.world.find({},{name:1,continent:1,_id:0}).sort([("continent",-1),("name",1)])

@@ Line 1: / Line 1: @@
-<pre class=setup>
-#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
-</pre>
 {{TopTenTips}}
 <div style="min-height:25em">
@@ Line 25: / Line 9: @@
 <div class="q nonum" data-lang="py3">Sort all the documents in world by continent descending, then name ascending. Show only name and continent.
 <pre class=def>
-pp.pprint(list(
+db.world.find({},{name:1,continent:1,_id:0}).sort([("continent",-1),("name",1)])
-    db.world.find({},{"name":1,"continent":1,"_id":0}).sort([("continent",-1),("name",1)])
-))
 </pre>
 </div>