How to query MongoDB documents with find and filters

find and findOne

find returns a cursor over all matching documents. findOne returns the first match or null if nothing matches. Passing an empty filter object {} matches every document in the collection. Cursors are lazy — MongoDB does not execute the query until you call .toArray(), iterate, or chain a terminal method.

// findOne — returns one document or null
const product = await db.collection('products').findOne({ name: 'Mouse' })

// find with comparison operators
const mid = await db.collection('products')
  .find({ price: { $gt: 50, $lte: 300 } }).toArray()

// Logical OR
const featured = await db.collection('products').find({
  $or: [{ inStock: true }, { price: { $lt: 20 } }]
}).toArray()

// Implicit AND — multiple fields in the same filter object
db.collection('products').find({ inStock: true, category: 'peripherals' })

Projection — control which fields are returned

The second argument to find limits which fields MongoDB sends over the network. Use 1 to include and 0 to exclude. You cannot mix include and exclude values in the same projection, except you can always explicitly exclude _id alongside inclusions.

// Return only name and price, suppress _id
db.collection('products').find({}, { name: 1, price: 1, _id: 0 })

Cursor control

db.collection('products')
  .find({ inStock: true })
  .sort({ price: -1 })  // descending
  .skip(20).limit(10)   // page 3 of 10-per-page results