Update Multiple Documents in MongoDB

Update Multiple Documents in MongoDB

Introduction:
In MongoDB, you can update multiple documents in a collection using various update operators and methods. This documentation will guide you through the process of updating multiple documents in MongoDB using both the MongoDB shell and a programming language (Python in this case). We will cover the basic update methods and provide examples for better understanding.

1. Updating Multiple Documents using MongoDB Shell:

MongoDB provides several update operators that allow you to modify multiple documents simultaneously.

1.1. The updateMany Method:

• The updateMany method updates all documents that match the specified filter in a collection.
• Syntax:

javascript
db.collection.updateMany(
  <filter>,
  <update>
)

• Explanation:
  • <filter>: Specifies the condition to match the documents for updating.
  • <update>: Specifies the modifications to be applied to the matched documents.

Example:
Let's say we have a collection named "users" with documents having a field "status." We want to set the "status" to "inactive" for all users with "lastActivity" older than 6 months.

javascript
db.users.updateMany(
  { lastActivity: { $lt: ISODate("2023-01-26T00:00:00Z") } },
  { $set: { status: "inactive" } }
)

2. Updating Multiple Documents using Python:

Python provides the "pymongo" library to interact with MongoDB.

2.1. Install pymongo:
You can install pymongo using pip:

bash
pip install pymongo

2.2. Using update_many Method:

• The update_many method in pymongo is used to update multiple documents that match a given filter in a collection.
• Syntax:

python
from pymongo import MongoClient

client = MongoClient("mongodb://localhost:27017/")
db = client["your_database"]
collection = db["your_collection"]

filter = { "age": { "$lt": 30 } }
update = { "$set": { "category": "young" } }

result = collection.update_many(filter, update)
print(f"Matched documents: {result.matched_count}")
print(f"Modified documents: {result.modified_count}")

Explanation:

• The code above will update all documents with the "age" field less than 30 and set their "category" to "young."
• result.matched_count will give the count of matched documents, and result.modified_count will give the count of modified documents.

Conclusion:
This documentation provided an overview of updating multiple documents in MongoDB using the MongoDB shell and Python. You learned about the updateMany method in the MongoDB shell and the update_many method in Python's pymongo library. With this knowledge, you can efficiently update multiple documents in your MongoDB collections.