Python and MongoDB

Christiano Anderson
Works with free software since 1995;
Former system engineer of Terra Networks Brazil;
Former GNU Free Software Directory maintainer;
Python developer since 2000, member of ApyB;
Member of MongoDB pt_BR translation team;
Founder of Trianguli free software;
Free Software and NoSQL evangelist;
3/263

What is MongoDB?
MongoDB is...
Open-Source,
High-Performance,
Schema-Free,
Document-Oriented
Database

What is MongoDB? ”MongoDB bridges the gap between key-value stores (which are fast and highly scalable) and traditional RDBMS systems (which provide rich queries and deep functionality).”

MongoDB in production

Schema-Free
Good at:
Dynamically typed languages;
Migrations;
Flexibility;
Web;
Caching;
Not good at:
Transactional datas;
If you require full SQL support;

Document
A document in MongoDB is like a JSON.
Example:
{'name': 'Christiano',
'language': 'Python',
'country': 'Brazil'}

Migrations?
You can dinamically update your data, example:
'country': 'Brazil'}
'country': 'Brazil',
'event': 'PyConAr'}

Aggregation
Distinct
db.programmers.insert({”language”:”python”})
db.programmers.insert({”language”:”perl”})
db.programmers.insert({”language”:”ruby”})
db.programmers.insert({”language”:”python”})
db.programmers.distinct(”language”)

Map/Reduce
Use JavaScript to create Map/Reduce functions
function () {
this.tags.forEach(function(z)) {
emit (z, 1);
});}
Function (key, value) {
var total = 0;
for (var i = 0; i < values.length; i++) {
total += values[i]; }
return total;
}

SQL to Mongo

More SQL to Mongo

Other cool features
Full index support;
GridFS;
Replication & High Availability;
Auto-Sharding;
Free software;
But also provides commercial support;

Using MongoDB with Python
PyMongo is the Python driver for MongoDB;
You can use setuptools to install:
$ easy_install pymongo
Or you can use GitHub:
$ git clone git://github.com/mongodb/mongo-python-driver.git pymongo
$ cd pymongo/
$ python setup.py install

Connecting
>>> from pymongo import Connection >>> con = Connection('localhost') >>> db = con['blog']

Inserting
>>> post = {'title':'My first post', …'author': 'Christiano Anderson', …'content': 'This is my first paragraph', … 'tags': ['mongodb','blog','example']} >>> posts = db['posts'] >>> posts.insert(post) ObjectId('4cb662f508bf532b1b000000')

Inserting more docs at once
>>> other_posts = [{'title':'Second Post', 'author': 'Christiano Anderson','tags':['test'], 'content': 'Hey, my second Post'}, {'title':'Third Post', 'author':'Luke Skywalker','tags':['naboo'],'content':'Hey princess Leya'}] >>> posts.insert(other_posts) [ObjectId('4cb6651b08bf532b97000000'), ObjectId('4cb6651b08bf532b97000001')]

Querying one doc
>>> my_post = db.posts.find_one({}) {u'content': u'This is my first post at MongoDB', u'title': u'My first post', u'_id': ObjectId('4cb662f508bf532b1b000000'), u'tags': [u'mongodb', u'blog', u'example'], u'author': u'Christiano Anderson'} >>> my_post = db.posts.find_one({ 'author': 'Christiano Anderson'})

Querying an array of docs
>>> all_posts = db.posts.find({}) >>> for p in all_posts: ... print p['title'] My first post Second Post Third Post

More queries
>>> p = db.posts.find_one({'tags':'naboo'}) {u'content': u'Hey princess Leya', u'title': u'Third Post', u'_id': ObjectId('4cb6651b08bf532b97000001'), u'tags': [u'naboo'], u'author': u'Luke Skywalker'}

Operators
You can use operators, like $ne, $lte, $gte, and many others. See more at:
http://www.mongodb.org/display/DOCS/Advanced+Queries

MongoEngine
An object-document mapper to connect to Python and MongoDB
Similar to Django ORM
$ easy_install mongoengine

MongoEngine example
class User(Document): email = StringField(required=True) first_name = StringField(max_length=50) last_name = StringField(max_length=50)

MongoEngine example 2
class Post(Document): title = StringField(max_length=120, required=True) author = ReferenceField(User) class TextPost(Post): content = StringField() class ImagePost(Post): image_path = StringField() class LinkPost(Post): link_url = StringField()

Adding data
u = User(email='anderson@trianguli.net', first_name='Christiano', last_name='Anderson')
u.save()

Accessing data
for u in User.objects:
print u.email

Django and MongoDB
Yes, it is possible, but...
There is no great solution for:
Auth;
Sessions;
Admin;
Other ORM issues;

Django and MongoDB
You can use MongoEngine to create model-like schema;
MongoEngine provides:
Authentication Backend;
Sessions Backend;
Works fine, but it is not a native Django solution (yet)

Django and MongoEngine Auth
Settings.py:
from mongoengine import *
connect('testblog')
…
AUTHENTICATION_BACKENDS = (
'mongoengine.django.auth.MongoEngineBackend',
)

Django and MongoDB Sessions
SESSION_ENGINE = 'mongoengine.django.sessions'

Try out!
Projects:
http://www.mongodb.org
http://mongoengine.org
Great article about MongoDB and Django
http://miud.in/fHE

Contribute
MongoDB Users Group
http://groups.google.com/group/mongodb-user
MongoDB in Spanish
http://www.mongodb.org/display/DOCSES/Inicio
#MongoDB at irc.freenode.net
MongoSpanish Blog
http://mongospanish.blogspot.com/

Gracias!!! - Questions? Christiano Anderson [email_address] Twitter: @dump Blog: http://christiano.me

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Python and MongoDB

by Christiano Anderson on Oct 16, 2010

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