Python + MongoDb

• this is a quick walk through python working with mongoD

Setup

1. First you need to download and install MongoDB database
2. Install pymongo
   • to install pymongo run the command

   pip install pymongo

Connecting to the Database

To connect to mongodb it is simple as doing the following:

import pymongo
client = pymongo.MongoClient(host="localhost", port=27017)

OR

import pymongo
client = pymongo.MongoClient("mongodb://localhost:27017/")

Creating a database

In mongoDB a database is only created if and only if it has contents in it:

• Creating a new database in mongoDb is simple as doing the following

import pymongo
client = pymongo.MongoClient(host="localhost", port=27017)
db = client["shop"]

Listing Created Database

• To list all created database using pymongo we do it as follows

print(client.list_database_names())

Creating a collection

Just like creating a database a collection will be created if and only if it contains some contents in it.

• Let's create a collection customers in our database.

Listing the collections that are in the database:

• To lists all the collections that are in the database we do it as follows:

print(db.collection_names())

Inserting Documents in a collection

• To insert documents in the collection we use the following methods:
  1. insert_one()
  2. insert_many()

1. insert_one()

• This method insert one document in the collection name example:

import pymongo
client = pymongo.MongoClient(host="localhost", port=27017)
db = client["shop"]
customers = db["customers"]
customer ={
    "name":"customer1",
}
cursor = customers.insert_one(customer)
print("Inserted", cursor.inserted_id)

2. insert_many()

• This method insert multiple documents in the collection:

import pymongo
client = pymongo.MongoClient(host="localhost", port=27017)
db = client["shop"]
customers = db["customers"]
customersInfo =[
    {"name":"customer3"}, {"name":"customer100"}
]
cursor = customers.insert_many(customersInfo)
print(cursor.inserted_ids)

Finding the docs

• There are two methods in mongoDB that are used to query documents from a collection which are:
  1. find()
  2. findOne()

1. findOne()

• used to get a single document that occurs first in a collection

cursor = customers.find_one({"name":"customer3"})
print(cursor)

1. find()

• get all the documents that meet a certain condition:

cursor = customers.find({"name":"customer3"})
for doc in cursor:
    print(doc)

Listing all the docs in the collection:

cursor = customers.find({})
for doc in cursor:
    print(doc)

Sotting documents

• In mongoDb the sort() method is used to sort the documents. For example let's sort our documents base on name:

Ascending order

cursor = customers.find().sort("name")
for doc in cursor:
    print(doc)
OR
cursor = customers.find().sort("name", 1)
for doc in cursor:
    print(doc)

Descending Order

cursor = customers.find().sort("name", -1)
for doc in cursor:
    print(doc)

Deleting documents

• To delete documents we use the following methods:
  1. delete_one()
  2. delete_many()

1. delete_one()

• To delete one document we use the delete_one() method the following is an example on how to delete a document that matches a condition:

cursor = customers.delete_one({"name": "customer100"})
print(cursor.raw_result)

1. delete_many()

• To delete many document we use the delete_many() method the following is an example on how to delete a documents that matches a condition:

cursor = customers.delete_many({"name": "customer3"})
print(cursor.raw_result)

Dropping a collection

• Dropping a collection means deleting a collection from a database. Let's delete our collection customers

cursor = customers.drop()
print(db.collection_names()) # []
print("Collection deleted")

Updating Collection

• To update a collection we use one of the methods which are:
  1. update_one()
  2. update_many()

1. update_one()

• to update a single collection that matches a query we do it as follows:

cursor = customers.update_one({"name": "Name1"}, {"$set": {"name": "Name100"}})
print(cursor.raw_result, cursor.modified_count)

2. update_many()

• to update all collections that matches a query we do it as follows:

cursor = customers.update_one({"name": "Name2"}, {"$set": {"name": "Name200"}})
print(cursor.raw_result, cursor.modified_count)

Limit the Result

To limit the results we use the limit() method which takes one parameter an integer which is the total number of documents that will be returned:

Suppose we have the following documents in our collection and we want to get only first 5 customers we can do it as follows:

{'_id': 1, 'name': 'John', 'address': 'Highway37'}
{'_id': 2, 'name': 'Peter', 'address': 'Lowstreet 27'}
{'_id': 3, 'name': 'Amy', 'address': 'Apple st 652'}
{'_id': 4, 'name': 'Hannah', 'address': 'Mountain 21'}
{'_id': 5, 'name': 'Michael', 'address': 'Valley 345'}
{'_id': 6, 'name': 'Sandy', 'address': 'Ocean blvd 2'}
{'_id': 7, 'name': 'Betty', 'address': 'Green Grass 1'}
{'_id': 8, 'name': 'Richard', 'address': 'Sky st 331'}
{'_id': 9, 'name': 'Susan', 'address': 'One way 98'}
{'_id': 10, 'name': 'Vicky', 'address': 'Yellow Garden 2'}
{'_id': 11, 'name': 'Ben', 'address': 'Park Lane 38'}
{'_id': 12, 'name': 'William', 'address': 'Central st 954'}
{'_id': 13, 'name': 'Chuck', 'address': 'Main Road 989'}
{'_id': 14, 'name': 'Viola', 'address': 'Sideway 1633'}

code:

cursor = customers.find().limit(5)
for doc in cursor:
    print(doc)

That's the basics about python + mongodb using pymongo

Cloud MongoDB

• Here

Credits:

• w3schools
• pymongo