MongoDB provides several methods to update existing documents in a collection:

updateOne(): Updates a single document that matches the filter. Example:

db.users.updateOne(
  { name: 'John Doe' },
  { $set: { age: 31, status: 'active' } }
)

updateMany(): Updates all documents that match the filter. Example:

db.users.updateMany(
  { status: 'inactive' },
  { $set: { status: 'active' } }
)

replaceOne(): Replaces a single document that matches the filter with a new document. Example:

db.users.replaceOne(
  { name: 'John Doe' },
  { name: 'John Doe', age: 31, email: 'john.new@example.com' }
)

Update operators:

$set: Sets the value of a field.
$unset: Removes the specified field.
$inc: Increments the value of a field by a specified amount.
$push: Adds an element to an array field.
$pull: Removes all instances of a value from an array.

Example using multiple operators:

db.users.updateOne(
  { name: 'John Doe' },
  {
    $set: { status: 'active' },
    $inc: { age: 1 },
    $push: { interests: 'hiking' }
  }
)

Upsert: If set to true, creates a new document when no document matches the filter. Example:

db.users.updateOne(
  { email: 'newuser@example.com' },
  { $set: { name: 'New User', age: 25 } },
  { upsert: true }
)

ArrayFilters: Allows updating specific array elements that match certain conditions. Example:

db.users.updateMany(
  { 'scores.subject': 'math' },
  { $set: { 'scores.$[element].score': 95 } },
  { arrayFilters: [{ 'element.score': { $lt: 90 } }] }
)

Updating Documents