Pymongo for the Clueless

PyMongo for the Clueless klrkdekira@gmail.com

http://www.python.org

http://www.mongodb.org/

● json-like (bson) document store● full index support● replication and high availability● auto sharding● querying● fast in-place update● map/reduce● GridFS

SQL to Mongo MappingMySQL Term MongoTermdatabase databasetable collectionindex indexrow BSON documentcolumn BSON fieldjoin embedding and linkingprimary key _id field

PyMongoThe romantic story of and

Connection Part 1>>> import pymongo>>> conn = pymongo.Connection()is equivalent to>>> conn = pymongo.Connection(localhost, 27017)Getting the database>>> db = conn.testdbis equivalent to>>> db = conn[testdb]

Basic Part 2Getting the collection>>> collection = db.test_collectionalso is equivalent to>>> collection = db[test_collection]Make it understood from now

Insert New Document(s)>>> dummy = db[dummy]>>> dummy.insert({key: a, value: 1})ObjectId(4e7c50eb059bf61d2f000000)Multiple insert>>> docs = [{key:b, value:2}, {key:c, value:3}]>>> dummy.insert(docs)[ObjectId(4e7c552a059bf61d2f000002), ObjectId(4e7c552a059bf61d2f000003)]

Find Part 1>>> dummy.find_one(){u_id: ObjectId(4e7c50eb059bf61d2f000000), ukey: ua, uvalue: 1}>>> dummy.find()<pymongo.cursor.Cursor object at 0x2810ed0>>>> for d in dummy.find(): print d{u_id: ObjectId(4e7c50eb059bf61d2f000000), ukey: ua, uvalue: 1}{u_id: ObjectId(4e7c5544059bf61d2f000004), ukey: ub,uvalue: 2}{u_id: ObjectId(4e7c5544059bf61d2f000005), ukey: uc,uvalue: 3}

Find Part 2>>> dummy.find_one({key:a}){u_id: ObjectId(4e7c50eb059bf61d2f000000), ukey: ua, uvalue: 1}Query by ObjectId>>> from bson.objectid import ObjectId>>> dummy.find_one({_id:ObjectId(4e7c50eb059bf61d2f000000)}){u_id: ObjectId(4e7c50eb059bf61d2f000000), ukey: ua, uvalue: 1}Same goes with find.

Update>>> dummy.update({key:a}, {value:2})Update multiple document, destructive>>> dummy.update({key:a}, {value:2}, multi=True)Just to overwrite attributes>>> dummy.update({key:a}, {$set:{value:2}})

DeleteRemove multiple file>>> dummy.remove({key:a})Remove by ObjectId>>> dummy.remove({_id:ObjectId(4e7c50eb059bf61d2f000000)})

Stored JS>>> db.system.js.add = "function (x, y) { return x + y; }">>> db.system.js.add(1, 2)3.0>>> del db.system.js.add

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Pymongo for the Clueless

by Chee Leong Chow on Sep 24, 2011

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