MongoDB: Update Embedded Documents

Learn how to update array fields in documents in MongoDB collections.

MongoDB provides the following methods to update existing documents in a collection:

To demonstrate the update operation, insert the following sample documents in the employees collection.

db.employees.insertMany([
    { 
        _id:1,
        firstName: "John",
        lastName: "King",
        email: "[email protected]",
        salary: 5000,
        skills: [ "Angular", "React", "MongoDB" ]
    },
    { 
        _id:2,
        firstName: "Sachin",
        lastName: "T",
        email: "[email protected]",
        salary: 8000,
        skills: [ "Accounting", "Tax" ]
    },
    { 
        _id:3,
        firstName: "James",
        lastName: "Bond",
        email: "[email protected]",
        salary: 7500,
        skills: [ "Sales", "Marketing" ]
    },
    { 
        _id:4,
        firstName: "Steve",
        lastName: "J",
        email: "[email protected]",
        salary: 7000,
        skills: [ "Mac", "Marketing", "Product Design" ]
    },
    { 
        _id:5,
        firstName: "Kapil",
        lastName: "D",
        email: "[email protected]",
        salary: 4500,
        skills: [ "Accounting", "Tax", "Sales" ]
    },
    { 
        _id:6,
        firstName: "Amitabh",
        lastName: "B",
        email: "[email protected]",
        salary: 7000,
        skills: [ "Marketing", "Tax" ]
    }
])

Update a Single Field

The following updates a single field in a single document in employees collection.

db.employees.updateOne({_id:1}, { $set: {firstName:'Morgan'}})

{
  acknowledged: true,
  insertedId: null,
  matchedCount: 1,
  modifiedCount: 1,
  upsertedCount: 0
}

In the above example, the first parameter is the filter criteria specified as a document, {_id:1} indicates that find a document whose _id is 1. The second parameter is used to specify fields and values to be modified on the matching document in the {<update-operator>: { field: value, field:value,... } format. Use the update operator to specify what action to perform. Here we want to set the value of a field, so use $set operator to specify fields and updated values in {field:updated-value} format.{ $set: {firstName:'Morgan'}} modifies the firstName to "Morgan" to the first document that matches with the specified criteria {_id:1}.

In the output, matchedCount indicates the number of documents that matched with the criteria, and modifiedCount indicates the number of documents updated. The updateOne() method will always modify a single document.

Now, check whether it has updated a value or not using the findOne() method shown below.

db.employees.find({_id:1})

{
  _id: 1,
  firstName: 'Morgan',
  lastName: 'King',
  email: '[email protected]',
  salary: 5000,
  skills: [ 'Angular', 'React', 'MongoDB' ],
  department: { name: 'IT' }
}

The updateOne() method adds the specified field if it does not exist in a matching document. For example, the following will add the location field.

db.employees.updateOne({firstName:"Steve"}, { $set: {location: "USA"}})

{
  acknowledged: true,
  insertedId: null,
  matchedCount: 1,
  modifiedCount: 1,
  upsertedCount: 0
}

Execute the following find() method to see the updated data.

db.employees.find({firstName:"Steve"})

{
    _id:4,
    firstName: "Steve",
    lastName: "J",
    email: "[email protected]",
    salary: 7000,
    location:"USA"
}

Use the $inc update operator to increase the value of the field by the specified amount.

db.employees.updateOne({firstName:"Steve"}, { $inc: {salary: 500}})

{
  acknowledged: true,
  insertedId: null,
  matchedCount: 1,
  modifiedCount: 1,
  upsertedCount: 0
}

Execute the following find() method to see the updated data.

db.employees.find({firstName:"Steve"})

{
    _id:4,
    firstName: "Steve",
    lastName: "J",
    email: "[email protected]",
    salary: 7500,
    location:"USA"
}

Update Multiple Fields

You can also specify multiple fields to update. The following updates email and lastName fields.

db.employees.updateOne({_id:2}, { $set: {lastName:"Tendulkar", email:"[email protected]"}})

{
  acknowledged: true,
  insertedId: null,
  matchedCount: 1,
  modifiedCount: 1,
  upsertedCount: 0
}

Execute the following find() method to see the updated data.

db.employees.find({_id:2})

{
    _id:2,
    firstName: "Sachin",
    lastName: "Tendulkar",
    email: "[email protected]",
    salary: 8000,
    skills: [ "Accounting", "Tax" ],
    department: { 
                "name":"Finance" 
            }
}

The updateOne() method updates a single document only, even if it finds multiple documents. For example, the following updates the first document even if it returns multiple documents.

db.employees.updateOne({salary:7000}, { $set: {salary:7500}})

{
  acknowledged: true,
  insertedId: null,
  matchedCount: 1,
  modifiedCount: 1,
  upsertedCount: 0
}

In the above example, the employees collection contains two documents that have salary:7000 field. However, the updateOne() modified a single document which is the first document from the matching result.

Update Array Elements

The $set operator overwrites the specified array instead of adding, removing, and updating array elements.

db.employees.updateOne({_id:5},{$set:{ skills:["Sales Tax"]}})

{
  acknowledged: true,
  insertedId: null,
  matchedCount: 1,
  modifiedCount: 1,
  upsertedCount: 0
}

In the above example, {$set:{ skills:["Sales Tax"]}} overwrites an existing array for {_id:5}.

db.employees.findOne({_id:5})

{
    _id: 5,
    firstName: 'Kapil',
    lastName: 'D',
    email: '[email protected]',
    salary: 4500,
    skills: [ 'Sales Tax' ],
    department: { name: 'Finance' },
    location: 'USA'
  }

Use the array operators to update single or multiple elements. The following updates an array element if found the specified element.

db.employees.updateOne({_id:2}, { $set: {"skills.$[element]":"Sales Tax"}},{ arrayFilters: [{ element: "Tax" }]})

{
  acknowledged: true,
  insertedId: null,
  matchedCount: 1,
  modifiedCount: 1,
  upsertedCount: 0
}

In the above example, {$set:{"skills.$[element]":"Sales Tax"}},{ arrayFilters: [{ element: "Tax" }]updates the skills array if it contains "Tax" element then updates it to "Sales Tax".{"skills.$[element]":"Sales Tax"} specifies that the make the array element value to "Sales Tax" where array filter specifies the criteria { arrayFilters: [{ element: "Tax" }] where array element is "Tax". So, it will update array element if found matching element specified by arrayFilters.