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      • MongoDB Update Document

      MongoDB provides multiple methods for updating documents, allowing you to update single or multiple documents.

      Update Single Document

      updateOne() Method

      db.collection.updateOne(filter, update, options)

      Basic Example

      // Update first matching document
db.users.updateOne(
  { name: "John" },
  { $set: { age: 26, updatedAt: new Date() } }
)

      Return Result

      {
  "acknowledged": true,
  "matchedCount": 1,
  "modifiedCount": 1
}

      Update Multiple Documents

      updateMany() Method

      db.collection.updateMany(filter, update, options)

      Basic Example

      // Update all matching documents
db.users.updateMany(
  { status: "inactive" },
  { $set: { status: "active" } }
)

      Update Operators

      $set - Set Field Value

      // Set single field
db.users.updateOne(
  { name: "John" },
  { $set: { age: 26 } }
)

// Set multiple fields
db.users.updateOne(
  { name: "John" },
  { $set: { age: 26, city: "Boston" } }
)

// Set nested field
db.users.updateOne(
  { name: "John" },
  { $set: { "address.city": "Boston" } }
)

// Set array element
db.users.updateOne(
  { name: "John" },
  { $set: { "tags.0": "VIP" } }
)

      $unset - Remove Field

      // Remove field
db.users.updateOne(
  { name: "John" },
  { $unset: { tempField: "" } }
)

// Remove multiple fields
db.users.updateOne(
  { name: "John" },
  { $unset: { tempField: "", oldField: "" } }
)

      $inc - Increment Value

      // Increment value
db.users.updateOne(
  { name: "John" },
  { $inc: { age: 1 } }  // age + 1
)

// Decrement value
db.users.updateOne(
  { name: "John" },
  { $inc: { age: -1 } }  // age - 1
)

// Increment multiple fields
db.products.updateOne(
  { name: "iPhone" },
  { $inc: { stock: -1, sold: 1 } }
)

      $mul - Multiply Value

      // Multiply value
db.products.updateOne(
  { name: "iPhone" },
  { $mul: { price: 0.9 } }  // 10% discount
)

      $rename - Rename Field

      // Rename field
db.users.updateMany(
  {},
  { $rename: { "oldName": "newName" } }
)

      Array Operators

      $push - Add Element to Array

      // Add single element
db.users.updateOne(
  { name: "John" },
  { $push: { tags: "VIP" } }
)

// Add multiple elements
db.users.updateOne(
  { name: "John" },
  { $push: { tags: { $each: ["VIP", "Premium"] } } }
)

// Add to specific position
db.users.updateOne(
  { name: "John" },
  { $push: { tags: { $each: ["New"], $position: 0 } } }
)

// Sort and limit
db.users.updateOne(
  { name: "John" },
  { $push: { scores: { $each: [85], $sort: -1, $slice: 3 } } }
)

      $addToSet - Add to Set (No Duplicates)

      // Add unique element
db.users.updateOne(
  { name: "John" },
  { $addToSet: { tags: "VIP" } }
)

// Add multiple unique elements
db.users.updateOne(
  { name: "John" },
  { $addToSet: { tags: { $each: ["VIP", "Premium", "VIP"] } } }
)

      $pop - Remove Array Element

      // Remove last element
db.users.updateOne(
  { name: "John" },
  { $pop: { tags: 1 } }
)

// Remove first element
db.users.updateOne(
  { name: "John" },
  { $pop: { tags: -1 } }
)

      $pull - Remove Specified Element

      // Remove specified value
db.users.updateOne(
  { name: "John" },
  { $pull: { tags: "VIP" } }
)

// Remove multiple values
db.users.updateOne(
  { name: "John" },
  { $pull: { tags: { $in: ["VIP", "Premium"] } } }
)

// Remove by condition
db.users.updateOne(
  { name: "John" },
  { $pull: { scores: { $lt: 60 } } }
)

      $pullAll - Remove All Specified Values

      db.users.updateOne(
  { name: "John" },
  { $pullAll: { tags: ["VIP", "Premium"] } }
)

      Replace Document

      replaceOne() Method

      db.users.replaceOne(
  { name: "John" },
  {
    name: "John",
    age: 26,
    city: "Boston"
    // Note: _id is not replaced
  }
)

      Update Options

      upsert - Insert if Not Exists

      db.users.updateOne(
  { name: "New User" },
  { $set: { age: 20, createdAt: new Date() } },
  { upsert: true }
)

      writeConcern

      db.users.updateOne(
  { name: "John" },
  { $set: { age: 26 } },
  {
    writeConcern: {
      w: "majority",
      j: true,
      wtimeout: 5000
    }
  }
)

      Bulk Update

      Bulk Operations

      var bulk = db.users.initializeUnorderedBulkOp()

bulk.find({ name: "John" }).updateOne({ $set: { age: 26 } })
bulk.find({ name: "Jane" }).updateOne({ $set: { age: 31 } })
bulk.find({ status: "inactive" }).update({ $set: { status: "active" } })

bulk.execute()

      Update Examples

      Comprehensive Example

      // Update user info and add operation log
db.users.updateOne(
  { _id: ObjectId("...") },
  {
    $set: {
      lastLogin: new Date(),
      loginCount: 1
    },
    $inc: { loginCount: 1 },
    $push: {
      loginHistory: {
        $each: [{ time: new Date(), ip: "192.168.1.1" }],
        $slice: -10  // Keep only last 10 entries
      }
    }
  }
)

      Summary

      Key points for updating documents:

      • updateOne() for single document updates
      • updateMany() for multiple document updates
      • replaceOne() to replace entire document
      • Use various operators for different update needs
      • upsert can "update if exists, insert if not"

      In the next chapter, we will learn about MongoDB Delete Document.