MongoDB
=========

**dealing with the javascript console**

Connect and show dbs
--------------------

::


	# mongo localhost:27017/eoleaaf

	show collections

	> help
	db.help()                    help on db methods
	db.mycoll.help()             help on collection methods
	sh.help()                    sharding helpers
	rs.help()                    replica set helpers
	help admin                   administrative help
	help connect                 connecting to a db help
	help keys                    key shortcuts
	help misc                    misc things to know
	help mr                      mapreduce

	show dbs                     show database names
	show collections             show collections in current database
	show users                   show users in current database
	show profile                 show most recent system.profile entries with time >= 1ms
	show logs                    show the accessible logger names
	show log [name]              prints out the last segment of log in memory, 'global' is default
	use <db_name>                set current database
	db.foo.find()                list objects in collection foo
	db.foo.find( { a : 1 } )     list objects in foo where a == 1
	it                           result of the last line evaluated; use to further iterate
	DBQuery.shellBatchSize = x   set default number of items to display on shell
	exit                         quit the mongo shell
	> show dbs
	admin              (empty)
	local              0.078GB
	mongoengine_test   0.078GB
	mongoengine_test2  0.078GB
	mongoengine_test3  0.078GB
	pymongo_test       0.078GB
	pymongo_test2      (empty)
	>

drop database::

    > db.dropDatabase()
    { "dropped" : "aaf", "ok" : 1 }

Find an entry
---------------

::

    > db.user.findOne()
    db.user.findOne({UserType:"eleve"})


- find an entry where a field exists::

    db.user.find({"ENTEleveClasses":{$exists:true}})

-  find an entry with a specific subfield::

    > db.user.find({"ENTEleveClasses":{$exists:true}}, {"ENTEleveClasses.name":1})
    { "_id" : ObjectId("59bfde67b92f3b1e9659cad9"), "ENTEleveClasses" : { "name" :
    "T STL" } }
    { "_id" : ObjectId("59bfde67b92f3b1e9659cada"), "ENTEleveClasses" : { "name" :
    "T STL" } }
    { "_id" : ObjectId("59bfde67b92f3b1e9659cadb"), "ENTEleveClasses" : { "name" :
    "T STL" } }


and filter it::

    > db.user.find({"UserType":"eleve", "ENTEleveClasses.name":"T STL"},
    {ENTPersonLogin:1})
    { "_id" : ObjectId("59bfde67b92f3b1e9659cad9"), "ENTPersonLogin" :
    "albertine.delacourt02" }
    { "_id" : ObjectId("59bfde67b92f3b1e9659cada"), "ENTPersonLogin" :
    "albertine.delacourt03" }
    { "_id" : ObjectId("59bfde67b92f3b1e9659cadb"), "ENTPersonLogin" :
    "albertine.delacourt04" }

Using groups
------------

::

    > db.user.aggregate([   { $match: {"FieldActionType" : "CREATE"}},    {
    $group: {       _id: null,        count: {         $sum: 1       }     }   }
    ]);
    { "_id" : null, "count" : 13 }
    > db.user.aggregate([   { $match: {"FieldActionType" : "CREATE"}},    {
    $group: {       _id: "$FieldActionType",        count: {         $sum: 1
    }     }   } ]);
    { "_id" : "CREATE", "count" : 13 }

    > db.user.aggregate([{      $group: {       _id: "$ENTEleveClasses"}   } ]);
    > db.user.aggregate([{      $group: {       _id: "$ENTEleveClasses",
    count: {         $sum: 1       }     }   } ]);

    > db.user.aggregate([{$match:{"UserType":"eleve"}}, {      $group: {
    _id: "$ENTEleveClasses"}   } ]);
    { "_id" : { "etablissement" : ObjectId("59bfde67b92f3b1e9659cad0"), "name" :
    "T STL" } }
    { "_id" : { "etablissement" : ObjectId("59bfde67b92f3b1e9659cacf"), "name" :
    "T STL" } }

    > db.user.aggregate([{$match:{"UserType":"eleve"}}, {      $group: {
    _id: "$ENTEleveClasses.name"}   } ]);
    { "_id" : "T STL" }