Python MongoDB Insert Document

In MongoDB, you can insert documents (which are similar to rows in a relational database) into collections. MongoDB documents are stored in JSON-like format called BSON (Binary JSON), but you can work with Python dictionaries to insert documents using the pymongo library.

Steps to Insert a Document into MongoDB Using Python

1. Install PyMongo (if not already installed):

   pip install pymongo
   

2. Connect to MongoDB, access the database, and insert documents into a collection.

Example: Inserting a Single Document

You can insert a single document using the insert_one() method.

import pymongo

# Step 1: Connect to MongoDB (adjust the URL as needed)
client = pymongo.MongoClient("mongodb://localhost:27017/")

# Step 2: Access or create a database
mydb = client["mydatabase"]

# Step 3: Access or create a collection
mycol = mydb["customers"]

# Step 4: Create a document (Python dictionary)
mydict = { "name": "John", "address": "123 Elm Street" }

# Step 5: Insert the document into the collection
x = mycol.insert_one(mydict)

# Step 6: Print the inserted document ID
print("Inserted document ID:", x.inserted_id)

Explanation:

1. Connect to MongoDB: We connect to the MongoDB instance on localhost (change the URL if connecting to a remote server).
2. Access or Create Database: The line client["mydatabase"] accesses the mydatabase database (creates it if it doesn’t exist yet).
3. Access or Create Collection: mycol = mydb["customers"] accesses the customers collection, which is created if it doesn’t exist.
4. Insert a Document: Using insert_one(), we insert the document (represented as a Python dictionary) into the customers collection.

Example: Inserting Multiple Documents

You can insert multiple documents at once using the insert_many() method.

import pymongo

# Step 1: Connect to MongoDB
client = pymongo.MongoClient("mongodb://localhost:27017/")

# Step 2: Access or create a database
mydb = client["mydatabase"]

# Step 3: Access or create a collection
mycol = mydb["customers"]

# Step 4: Create multiple documents (list of Python dictionaries)
mylist = [
  { "name": "Amy", "address": "456 Oak Street" },
  { "name": "Mark", "address": "789 Maple Avenue" },
  { "name": "Sara", "address": "101 Pine Road" }
]

# Step 5: Insert multiple documents into the collection
x = mycol.insert_many(mylist)

# Step 6: Print the inserted document IDs
print("Inserted document IDs:", x.inserted_ids)

Explanation:

• We create a list of dictionaries, where each dictionary represents a document to be inserted.
• insert_many() is used to insert multiple documents into the collection.
• The inserted_ids attribute returns a list of IDs for the inserted documents.

Inserting a Document with an Explicit _id

MongoDB automatically creates a unique _id field for each document. However, you can explicitly set the _id if needed:

mydict = { "_id": 1, "name": "John", "address": "123 Elm Street" }
x = mycol.insert_one(mydict)

If you try to insert a document with a duplicate _id, it will raise an error.

Handling Errors

When inserting data, you might want to handle potential errors, such as trying to insert a document with a duplicate _id:

from pymongo.errors import DuplicateKeyError

mydict = { "_id": 1, "name": "John", "address": "123 Elm Street" }

try:
    x = mycol.insert_one(mydict)
    print("Inserted document ID:", x.inserted_id)
except DuplicateKeyError:
    print("Document with that _id already exists.")

Example: Full Flow (Connecting, Inserting, and Retrieving Data)

import pymongo

# Step 1: Connect to MongoDB
client = pymongo.MongoClient("mongodb://localhost:27017/")

# Step 2: Access or create a database
mydb = client["mydatabase"]

# Step 3: Access or create a collection
mycol = mydb["customers"]

# Step 4: Insert a document
mydict = { "name": "John", "address": "123 Elm Street" }
mycol.insert_one(mydict)

# Step 5: Insert multiple documents
mylist = [
  { "name": "Amy", "address": "456 Oak Street" },
  { "name": "Mark", "address": "789 Maple Avenue" },
  { "name": "Sara", "address": "101 Pine Road" }
]
mycol.insert_many(mylist)

# Step 6: Retrieve all documents in the collection
for doc in mycol.find():
    print(doc)

This example inserts both a single document and multiple documents into the customers collection, then retrieves all documents from the collection using the find() method.

Summary:

• insert_one(): Use this method to insert a single document into a collection.
• insert_many(): Use this method to insert multiple documents at once.
• MongoDB automatically creates an _id field for each document unless you provide one explicitly.
• Handle potential errors, such as duplicate _id insertions, using appropriate error handling (DuplicateKeyError).