Python MongoDB

MongoDB is one of the most popular NoSQL databases currently, using the BSON data type (similar to JSON).

For MongoDB database installation and introduction, you can check ourMongoDB Tutorial.

PyMongo

To connect Python to MongoDB, you need a MongoDB driver. Here we use the PyMongo driver to connect.

pip Installation

pip is a general-purpose Python package management tool that provides functions for searching, downloading, installing, and uninstalling Python packages.

Install pymongo:

$ python3 -m pip3 install pymongo

You can also specify the version to install:

$ python3 -m pip3 install pymongo==3.5.1

Update pymongo command:

$ python3 -m pip3 install --upgrade pymongo

easy_install Installation

Older versions of Python can use easy_install to install, easy_install is also a Python package management tool.

$ python -m easy_install pymongo

Update pymongo command:

$ python -m easy_install -U pymongo

Test PyMongo

Next, we can create a test file demo_test_mongodb.py, with the following code:

demo_test_mongodb.py file code:

#!/usr/bin/python3 import pymongo

Execute the above code file. If no error occurs, the installation is successful.

Create Database

Create a Database

To create a database, you need to use the MongoClient object and specify the URL address of the connection and the name of the database to be created.

In the following example, we create the database exampledb:

Example

#!/usr/bin/python3 import pymongo myclient = pymongo.MongoClient("mongodb://localhost:27017/") mydb = myclient["exampledb"]

Note:In MongoDB, a database is only created after content is inserted! That is to say, after creating a database, you must create a collection (data table) and insert a document (record) before the database is actually created.

Determine if the database already exists

We can read all databases in MongoDB and determine whether the specified database exists:

Example

#!/usr/bin/python3 import pymongo myclient = pymongo.MongoClient('mongodb://localhost:27017/') dblist = myclient.list_database_names() # dblist = myclient.database_names() if "exampledb" in dblist: print("The database already exists!")

Note:database_names is deprecated in the latest version of Python. After Python 3.7+, it was changed to list_database_names().

Create Collection

Collections in MongoDB are similar to tables in SQL.

Create a Collection

MongoDB uses database objects to create collections, as shown in the example below:

Example

#!/usr/bin/python3 import pymongo myclient = pymongo.MongoClient("mongodb://localhost:27017/") mydb = myclient["exampledb"] mycol = mydb["sites"]

Note:In MongoDB, a collection is only created after content is inserted! That is to say, after creating a collection (data table), you must insert a document (record) before the collection is actually created.

Determine if the collection already exists

We can read all collections in the MongoDB database and determine whether the specified collection exists:

Example

#!/usr/bin/python3 import pymongo myclient = pymongo.MongoClient('mongodb://localhost:27017/') mydb = myclient['exampledb'] collist = mydb. list_collection_names() # collist = mydb.collection_names() if "sites" in collist: # Determine whether the sites collection exists print("The collection already exists!")

Note:collection_names is deprecated in the latest version of Python. After Python 3.7+, it was changed to list_collection_names().

Operations such as add, delete, update, and query

The following table lists more MongoDB operations. Click on the specific link for details:

Serial number Function
1 Add data
2 Query data
3 Modify data
4 Data sorting
5 Delete data
Other extensions