A single document in a MongoDB collection that matches a given filter can be updated using the updateOne() method. When the filter returns more than one document, only the first one will be updated and nothing will be changed if there are no documents that fit the filter.

1. Syntax of updateOne()

Following is the syntax of the updateOne() method.

# Syntax
db.collection.updateOne( , ,
{
update_option
}
)

The filter_document parameter indicates the selection criteria for the document to update.

The $set operator is passed as a parameter where the modifications apply to the selected document.

The update_option specifies that the updateOne() method takes different options that modify the fields in the selected document.

In order to explain the updateOne() method in MongoDB, let’s create the sample collection with a few documents.

# Create Collection by inserting some documents
db.student.insertMany([
{
_id: 1,
name: “Jermy”,
age: 24,
marks: 500,
email: “jermy@gmail.com”,
course: [“Python”, “MongoDB”, “Java”],
points: [10, 9, 3]
},
{
_id: 2,
name: “Niki”,
age: 20,
marks: 450,
email: “niki@gmail.com”,
course: [“Python”, “MongoDB”, “Java”],
points: [5, 9, 3]
},
{
_id: 3,
name: “Ian”,
age: 24,
marks: 400,
email: “ian@gmail.com”,
course: [“Python”, “MongoDB”, “Java”],
points: [12, 5, 13]
},
{
_id: 4,
name: “Tyler”,
age: 23,
marks: 390,
email: “tyler@gmail.com”,
course: [“Python”, “MongoDB”, “Java”],
points: [5, 10, 9]
}
]
)

2. Using MongoDB updateOne() method to update the document

The updateOne() method only updates the initial document that satisfies the filter. The query is specified with the updateOne() method that updates one document that matches the specified filter. Furthermore, the updateOne() method takes the filter that selects the document to be updated based on the value of the name field equal to Jermy. Then, the updateOne() method takes the $set operator to set the value of the age field to 20 for the selected document.

# Updating One document
db.student.updateOne({name: “Jermy”}, {$set:{age:20}})

The following output yielded indicates that one document has been modified and matched.

The following updated document can be read below.

3. Using the updateOne() method to update the document with a new field

Moreover, the updateOne() method also adds a field that is not found in the matched document. The query below called the updateOne() method, with the filter as the first argument to modify the document. The filter uses the name field to match records where Ian appears in the document.

After that, the $set operator is assigned as a second argument of the updateOne() method. Here, the $set operator inserts New York as the value for the location field for the selected document. Note that location doesn’t exist in any of the documents in the collection student. But the updateOne() method will insert this field with the specified value in the filtered document.

# Updating document with new field
db.student.updateOne({name:”Ian”},{$set:{location:”New york”}})

The following output represents that the document is matched and modified.

Furthermore, we can see the modified and matched document with the new field location.

4. Using the updateOne() method to update the document by increasing the value

The updateOne() method also accepts the $inc operator to increment a numeric field by a specified value. The given query of the updateOne() method updates the document one document that matches the specified filter. As the _id column has a value of 4, the filter chooses the updated document according to that value.

Furthermore, the updateOne() method is set with the $inc operator that increments the value of the marks field by 400 for the selected document.

# Updating documents by increasing value
db.student.updateOne({_id: 4}, { $inc: {marks: 400}})

The following result shows that the document is updated by incrementing a specified value of the field.

We read the modified document that appears with the increased value of the marks field below.

5. Using the updateOne() method to add the new document if it doesn’t exist

Further, the upsert option can be used in the updateOne() method to insert the new document if one does not already exist that meets the specified filter. The query of the updateOne() method updates the value of the age and email fields for the document that matches the filter, respectively.

Note that we have specified the upsert option after the $set operator, which creates a new document if one does not already exist that match the specified filter. If there is no document in the student collection that matches the filter, MongoDB will create a new document with the name, age, and email fields set to the given values, respectively.

# Adding new document if it doesn’t exist
db.student.updateOne({name:”stefan”},
{ $set: {age:27, email:”stefan@gmail.com”}},
{ upsert: true }
)

The following output retrieved below indicates that the matched document is not found. But that document has been added to the collection.

The new document upserted in the collection student like this.

If you want to know how to insert a document if it does not exist, you can use the following link.

6. Using the updateOne() method to update the array fields of the document

The arrays can also be modified via the updateOne() method. The updateOne() method query modified the value of the first and second elements of the course array in the document that matches the filter to C++ and C#, respectively. Here, the course field is an array, and the notation . dot indicates each element’s position within the array.

# Updating array fields in document
db.student.updateOne({ _id: 3 },
{ $set: {
“course.0”: “C++”,
“course.1”: “C#”
}
})

The output verifies that the document is matched and updated the array value.

Now, we have retrieved the document updated with the array field values.

7. Conclusion

In conclusion, you have learned the MongoDB updateOne() method that is used to update one document. The updateOne() method in MongoDB offers a variety of update operators that can be used to modify a single document in a collection that matches a given filter.

More details about this topic can be found here.

MongoDB updateOne() Method Explained AQSA Spark By {Examples}