Examples of MongoDB update

Let set up an environment:

To understand MongoDB update we need a collection called students on which we will perform various operations and queries.

[
  { _id: 1, name: "Alice", age: 25, grades: [
      { grade: "Maths", score: 80 },
      { grade: "Science", score: 85 }
    ]
  },
  { _id: 2, name: "Bob", age: 30, grades: [
      { grade: "Maths", score: 75 },
      { grade: "Science", score: 90 }
    ]
  },
  { _id: 3, name: "Charlie", age: 35, grades: [
      { grade: "Maths", score: 95 },
      { grade: "Science", score: 88 }
    ]
  }
]

Example 1: Update a Single Document

Write a query to update the age of a student named Alice to 26 in the “students” collection.

db.students.updateOne(
   { name: "Alice" },
   { $set: { age: 26 } }
)

Output:

[
  {
    _id: 1,
    name: 'Alice',
    age: 26,
    grades: [ { grade: 'Maths', score: 80 }, { grade: 'Science', score: 85 } ]
  },
  {
    _id: 2,
    name: 'Bob',
    age: 30,
    grades: [ { grade: 'Maths', score: 75 }, { grade: 'Science', score: 90 } ]
  },
  {
    _id: 3,
    name: 'Charlie',
    age: 35,
    grades: [ { grade: 'Maths', score: 95 }, { grade: 'Science', score: 88 } ]
  }
]

Example 2: Use Update Operator Expressions ($inc and $set)

Write a query to increment the age of a student named Bob by 1 in the “students” collection.

db.students.updateOne(
   { name: "Bob" },
   { $inc: { age: 1 } }
)

Output:

[
  {
    _id: 1,
    name: 'Alice',
    age: 26,
    grades: [ { grade: 'Maths', score: 80 }, { grade: 'Science', score: 85 } ]
  },
  {
    _id: 2,
    name: 'Bob',
    age: 31,
    grades: [ { grade: 'Maths', score: 75 }, { grade: 'Science', score: 90 } ]
  },
  {
    _id: 3,
    name: 'Charlie',
    age: 35,
    grades: [ { grade: 'Maths', score: 95 }, { grade: 'Science', score: 88 } ]
  }
]

Example 3: Insert a New Document if No Match Exists (Upsert)

Write a query to update the age of a student named Charlie to 30 in the “students” collection. If Charlie does not exist, a new document should be inserted with the specified age.

db.students.updateOne(
   { name: "Charlie" },
   { $set: { age: 30 } },
   { upsert: true }
)

Output:

[
  {
    _id: 1,
    name: 'Alice',
    age: 26,
    grades: [ { grade: 'Maths', score: 80 }, { grade: 'Science', score: 85 } ]
  },
  {
    _id: 2,
    name: 'Bob',
    age: 31,
    grades: [ { grade: 'Maths', score: 75 }, { grade: 'Science', score: 90 } ]
  },
  {
    _id: 3,
    name: 'Charlie',
    age: 30,
    grades: [ { grade: 'Maths', score: 95 }, { grade: 'Science', score: 88 } ]
  }
]

Example 4: Upsert with Duplicate Values

Write a query to update the age of a student named Alice to 26 in the “students” collection. If Alice does not exist, a new document should be inserted with the specified age.

db.students.updateOne(
   { name: "Alice" },
   { $set: { age: 26 } },
   { upsert: true }
)

Output:

[
  {
    _id: 1,
    name: 'Alice',
    age: 26,
    grades: [ { grade: 'Maths', score: 80 }, { grade: 'Science', score: 85 } ]
  },
  {
    _id: 2,
    name: 'Bob',
    age: 31,
    grades: [ { grade: 'Maths', score: 75 }, { grade: 'Science', score: 90 } ]
  },
  {
    _id: 3,
    name: 'Charlie',
    age: 30,
    grades: [ { grade: 'Maths', score: 95 }, { grade: 'Science', score: 88 } ]
  }
]

Example 5: Update with Aggregation Pipeline

Write a query to update the age of a student named Alice by incrementing it by 1 in the “students” collection using an aggregation pipeline in the update operation.

db.students.updateOne(
   { name: "Alice" },
   [
      { $set: { age: { $add: ["$age", 1] } } }
   ]
)

Output:

[
  {
    _id: 1,
    name: 'Alice',
    age: 27,
    grades: [ { grade: 'Maths', score: 80 }, { grade: 'Science', score: 85 } ]
  },
  {
    _id: 2,
    name: 'Bob',
    age: 31,
    grades: [ { grade: 'Maths', score: 75 }, { grade: 'Science', score: 90 } ]
  },
  {
    _id: 3,
    name: 'Charlie',
    age: 30,
    grades: [ { grade: 'Maths', score: 95 }, { grade: 'Science', score: 88 } ]
  }
]

Example 6: Update Elements Match arrayFilters Criteria

Write a query to update the score of a student’s “Maths” grade to 85 using an array filter in the “students” collection

db.students.updateOne(
   { _id: 1 },
   { $set: { "grades.$[elem].score": 85 } },
   { arrayFilters: [ { "elem.grade": { $eq: "Maths" } } ] }
)

Output:

[
  {
    _id: 1,
    name: 'Alice',
    age: 27,
    grades: [ { grade: 'Maths', score: 85 }, { grade: 'Science', score: 85 } ]
  },
  {
    _id: 2,
    name: 'Bob',
    age: 31,
    grades: [ { grade: 'Maths', score: 75 }, { grade: 'Science', score: 90 } ]
  },
  {
    _id: 3,
    name: 'Charlie',
    age: 30,
    grades: [ { grade: 'Maths', score: 95 }, { grade: 'Science', score: 88 } ]
  }
]

Example 7: Update Specific Elements of an Array of Documents

Write a query to update the score of a student’s “Science” grade to 90 using an array filter in the “students” collection

db.students.updateOne(
   { _id: 1 },
   { $set: { "grades.$[elem].score": 90 } },
   { arrayFilters: [ { "elem.grade": { $eq: "Science" } } ] }
)

Output:

[
  {
    _id: 1,
    name: 'Alice',
    age: 27,
    grades: [ { grade: 'Maths', score: 85 }, { grade: 'Science', score: 90 } ]
  },
  {
    _id: 2,
    name: 'Bob',
    age: 31,
    grades: [ { grade: 'Maths', score: 75 }, { grade: 'Science', score: 90 } ]
  },
  {
    _id: 3,
    name: 'Charlie',
    age: 30,
    grades: [ { grade: 'Maths', score: 95 }, { grade: 'Science', score: 88 } ]
  }
]

MongoDB update operations allow us to modify documents in a collection. These operations can update a single document or multiple documents based on specified criteria.

MongoDB offers various update operators to perform specific actions like setting a value, incrementing a value or updating elements within arrays. In this article, We will learn about MongoDB update() by understanding various examples in detail.