Update documents

Update one document

To update a document in MongoDB you need to configure 2 basic things:

1. A filter definition that defines which document should be updated

2. An update definition that defines what should be updated in the matched document

After configuring the above two, you use the UpdateOne method on an IMongoCollection<T> reference.

Syntax

IMongoCollection<T>
    .UpdateOne(FilterDefinition<T> filter, 
                UpdateDefinition<T> update)

The following example updates the phone number of a user's document filter by its id.

C#

UpdateDocuments.cs

var personsCollection = usersDatabase.GetCollection<User>("users");

// Create an equality filter
var filter = Builders<User>.Filter
    .Eq(person => person.Id, appPerson.Id);

// Create an update definition using the Set operator    
var update = Builders<User>.Update
    .Set(person => person.Phone, "123-456-789");

// Update the document
var personUpdateResult = await personsCollection.UpdateOneAsync(filter, update);
if (personUpdateResult.MatchedCount == 1 && personUpdateResult.ModifiedCount == 1)
{
    Utils.Log( $"Document {appPerson.Id} Updated");
}

Bson

Shell

UpdateOne method returns an UpdateResult result that indicates the result of the update operation.

1. MatchedCount: The number of documents matched your filter definition

2. ModifiedCount: The number of documents updated

3. IsAcknowledged: Indicates whether the result is acknowledged

4. UpsertedId: The upserted id, if one exists

Remember that if the document already has the same value that you want to update to, modifiedCount will be 0

Update multiple documents

To update many documents at once, follow the same process but this time use the UpdateMany method.

Syntax

IMongoCollection<T>
    .UpdateMany(FilterDefinition<T> filter, 
                UpdateDefinition<T> update)

The following example filters user documents having salary greater than 1200 and less than 3500 and set the salary value to 4000.

C#

UpdateDocuments.cs

// Create a filter by combining a Greater & Less than filters
var salaryFilter = Builders<User>.Filter
    .And(
        Builders<User>.Filter.Gt(person => person.Salary, 1200),
        Builders<User>.Filter.Lt(person => person.Salary, 3500)
        );

// This is just for demonstration - validate the update result
var totalPersons = await personsCollection
    .Find(salaryFilter).CountDocumentsAsync();

// Create an update definition using the Set operator 
var updateDefinition = Builders<User>.Update
    .Set(person => person.Salary, 4000);

var updateResult = await personsCollection
    .UpdateManyAsync(salaryFilter, updateDefinition);

if (updateResult.MatchedCount.Equals(totalPersons))
{
    Utils.Log($"Salary has been updated for {totalPersons}");
}

Bson

Shell

Data