Update all Documents in a Collection using PyMongo

MongoDB is an open-source document-oriented database. MongoDB stores data in the form of key-value pairs and is a NoSQL database program. The term NoSQL means non-relational.

PyMongo contains tools which are used to interact with the MongoDB database. Now let's see how to update all the documents in a collection.

Updating all Documents in a Collection

PyMongo includes an update_many() function which  updates all the documents which satisfy the given query.

update_many() accepts the following parameters -

1.  filter - It is the first parameter which is a criteria according to which the documents that satisfy the query are updated.
2. update operator- It is the second parameter which contains the information to be updated in the documents.
3. upsert- (Optional) It is a boolean. If set to true and there is no document matching the filter, a new document is created.
4. array_filters - (Optional) It is an array of filter documents to determine which array elements to modify for an update operation on an array field.
5. bypass_document_validation - (Optional) A boolean which skips the document validation when set to True.
6. collation - (Optional) specifies the language specific rules for the operation.
7. session - (Optional) a ClientSession.

Update Operators in MongoDB

Setting Values:

• $set: Used to set a fields value.
• $setOnInsert: Update value only if a new document insertion.
• $unset: Remove the field and its value.

Numeric Operators:

• $inc: Increases the value by a given amount.
• $min/$max: returns minimum or maximum of value.
• $mul: multiplies the values by a given amount.

Miscellaneous Operators:

• $currentDate: Updates value of a field to current date.
• $rename: Renames a field

Now let's understand through some examples.

Sample Database:

Some use cases we are going to see in this article where updating many records can be useful: 

1. Changing or incrementing several elements based on a condition.
2. Inserting a new field to multiple or all documents.

Example 1: All the students with marks greater than 35 has been passed.

Database After Query: 

Example 2: New field called address added to all documents

Database After query: