MongoDB with pyMongo I - Installation

List of MongoDB with PyMongo

1. MongoDB with PyMongo I - Installing MongoDB
2. MongoDB with PyMongo II - Connecting and accessing MongoDB
3. MongoDB with pyMongo III - Range Querying MongoDB
4. MongoDB RESTful API with Flask

1. Flexible schema - supports hierarchical data structure.
2. Oriented toward programmers - it supports associative arrays such as php arrays, python dictionaries, JSON objects, Ruby hash etc.
3. Lots of MongoDB Drivers and Client Libraries
   Drivers in MongoDB are used for connectivity between client applications and the database. For example, if we have a Python program and we want to connect to MongoDB, then we need to download and integrate the Python driver so that the program can work with the MongoDB database. PyMongo is the driver for Python.
   
   
   

   Picture source : MongoDB Introduction; Schema Design

   
   
4. Flexible deployment.
5. Designed for BigData.
6. Aggregation Framework.

This tutorial is largely based on PyMongo and Install MongoDB on Ubuntu.

We need to make sure that the PyMongo distribution installed. If so, in the Python shell, the following should run without raising an exception:

>>> import pymongo

If not, on Ubuntu 14, install it like this:

$ sudo apt-get install python-setuptools
$ sudo easy_install pymongo

Or just use "pip"

$ pip install pymongo

PyMongo is just a driver. How about the MongoDB?

Reference: Install MongoDB on Ubuntu.

The Ubuntu package management tool (i.e. dpkg and apt) ensure package consistency and authenticity by requiring that distributors sign packages with GPG keys. Issue the following command to import the MongoDB public GPG Key:

$ sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv EA312927

Create a /etc/apt/sources.list.d/mongodb.list file using the following command.

$ echo "deb http://repo.mongodb.org/apt/ubuntu trusty/mongodb-org/3.2 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-3.2.list

Now issue the following command to reload your repository:

$ sudo apt-get update

The following command installs the latest stable version of MongoDB:

$ sudo apt-get install -y mongodb-org

When this command completes, you have successfully installed MongoDB! Continue for configuration and start-up suggestions.

Ref : Run MongoDB Community Edition

"The MongoDB instance stores its data files in /var/lib/mongo and its log files in /var/log/mongo, and runs using the mongod user account. If you change the user that runs the MongoDB process, you must modify the access control rights to the /var/lib/mongo and /var/log/mongo directories."

Start / Stop MongoDB

$ sudo service mongodb start
start: Job is already running: mongodb

$ sudo service mongodb stop
mongodb stop/waiting

$ sudo service mongodb start
mongodb start/running, process 12648

Restart MongoDB

You may restart the mongod process by issuing the following command:

sudo service mongodb restart

mongod is the primary daemon process for the MongoDB system. It handles data requests, manages data format, and performs background management operations.

We can start the mongod process by issuing the following command:

$ sudo mongod start

We may get dbpath error because unless specified, the mongod will look for data files in the default /data/db directory, but it's not there or the directory does not have proper permission. So, we should do this:

$ sudo mkdir -p /data/db
$ sudo chmod -R 755 /data/db

# m.py

def get_db():
    from pymongo import MongoClient
    client = MongoClient('localhost:27017')
    db = client.myFirstMB
    return db

def add_country(db):
    db.countries.insert({"name" : "Canada"})
    
def get_country(db):
    return db.countries.find_one()

if __name__ == "__main__":

    db = get_db() 
    add_country(db)
    print get_country(db)

Run:

$ python m.py
/usr/lib/python2.7/dist-packages/pkg_resources.py:1031: UserWarning: /home/k/.python-eggs is writable by group/others and vulnerable to attack when used with get_resource_filename. Consider a more secure location (set with .set_extraction_path or the PYTHON_EGG_CACHE environment variable).
  warnings.warn(msg, UserWarning)
{u'_id': ObjectId('53c181ce8ce4b12ad763c1dd'), u'name': u'Canada'}

We got a successful run with a warning related to the permission for group/others, but we can easily remove the waring:

$ chmod g-wx,o-wx ~/.python-eggs

$ python m.py
{u'_id': ObjectId('53c181ce8ce4b12ad763c1dd'), u'name': u'Canada'}

Our task for successful run has been accomplished. We just wanted to see how pymongo works and how easy it is to start using it.

Note that the code was run against a MongoDB instance (mongod) that we have provided.

$ ps -ef|grep mongod
mongodb  10407     1  1 10:18 ?        00:01:57 /usr/bin/mongod --config /etc/mongodb.conf

For more details about the inner workings of the code, please visit my next tutorial: Connecting and accessing MongoDB.

List of MongoDB with PyMongo

1. MongoDB with PyMongo I - Installing MongoDB
2. MongoDB with PyMongo II - Connecting and accessing MongoDB
3. MongoDB with pyMongo III - Range Querying MongoDB
4. MongoDB RESTful API with Flask