👐 UPDATE → updateOne(), updateMany()

To modify existing documents, MongoDB provides:

• .updateOne(): Updates the first matching document.
• .updateMany(): Updates all matching documents.

Syntax

db.collection.updateOne(
  { <query> },
  { <update operation> },
  { <options> }
)

• <query>: Specifies which document to update

• <update operation>: Defines modifications using update operators like $set, $inc, etc.

• <options>: (Optional) Allows additional configurations like upsert: true

Example: Update a book

db.reviews.updateOne(
  { bookId: "0312979509" }, // <-- query
  { $set: { rating: 5 } } // <-- update operation
);

Equivalent SQL query

UPDATE reviews SET rating = 5 WHERE bookId = '0312979509';

Upsert option

Let's say we want to update a review in our database from "John" for the book "0312979509" by rating it 5 stars.

db.reviews.updateOne(
  { name: "John", bookId: "0312979509" },
  { $set: { rating: 5 } }
);

Suppose "John" had never posted a review for this book before. The above query won't really do anything. In some cases, we may want to store a fresh new review based on the condition and updates mentioned in query. To handle such scenarios in MongoDB, we don't have to write additional application code to achieve this. All we have to do is utilize the upsert option.

db.reviews.updateOne(
  { name: "John", bookId: "0312979509" },
  { $set: { rating: 5 } },
  { upsert: true } //<-- option
);

info

Executing the above command will insert a fresh new document in the collection, like this:

{
  _id: ObjectId('679d...'),
  bookId: '0312979509',
  name: 'John',
  rating: 5
}

---

Challenge

👐 1. Update the pages of the book "Treasure of the Sun" to 449.

Answer

  db.books.updateOne(
    {"title": "Treasure of the Sun"}, 
    {$set: {pages: 449}}
  );