Update One

Overview

In this guide, you can learn how to use the MongoDB .NET/C# Driver to update values in a single document.

The .NET/C# Driver provides the following methods to update values:

• UpdateOne(): Updates one or more fields in a single document.

• UpdateOneAsync(): The asynchronous version of UpdateOne().

The following sections describe these methods in more detail.

public class Restaurant
{
    public ObjectId Id { get; set; }
    public string Name { get; set; }
    [BsonElement("restaurant_id")]
    public string RestaurantId { get; set; }
    public string Cuisine { get; set; }
    public Address Address { get; set; }
    public string Borough { get; set; }
    public List<GradeEntry> Grades { get; set; }
}

public class Address
{
    public string Building { get; set; }
    [BsonElement("coord")]
    public double[] Coordinates { get; set; }
    public string Street { get; set; }
    [BsonElement("zipcode")]
    public string ZipCode { get; set; }
}

public class GradeEntry
{
    public DateTime Date { get; set; }
    public string Grade { get; set; }
    public float? Score { get; set; }
}

Methods and Parameters

The UpdateOne() and UpdateOneAsync() methods accept the following parameters:

Update Multiple Values

The UpdateOne() and UpdateOneAsync() methods each accept only one UpdateDefinition object. The following sections describe how to update multiple values in a single method call.

var filter = Builders<Restaurant>.Filter
    .Eq("name", "Downtown Deli");
var combinedUpdate = Builders<Restaurant>.Update.Combine(
    Builders<Restaurant>.Update.Set("cuisine", "French"),
    Builders<Restaurant>.Update.Unset("borough")
);
_restaurantsCollection.UpdateOne(filter, combinedUpdate);

var filter = Builders<Restaurant>.Filter
    .Eq("name", "Downtown Deli");
var combinedUpdate = Builders<Restaurant>.Update.Combine(
    Builders<Restaurant>.Update.Set("cuisine", "French"),
    Builders<Restaurant>.Update.Unset("borough")
);
await _restaurantsCollection.UpdateOneAsync(filter, combinedUpdate);

var filter = Builders<Restaurant>.Filter
    .Eq("name", "Downtown Deli");
var updatePipeline = Builders<Restaurant>.Update.Pipeline(
    PipelineDefinition<Restaurant, Restaurant>.Create(
        new BsonDocument("$set", new BsonDocument("cuisine", "French")),
        new BsonDocument("$unset", "borough")
    )
);
_restaurantsCollection.UpdateOne(filter, updatePipeline);

var filter = Builders<Restaurant>.Filter
    .Eq("name", "Downtown Deli");
var updatePipeline = Builders<Restaurant>.Update.Pipeline(
    PipelineDefinition<Restaurant, Restaurant>.Create(
        new BsonDocument("$set", new BsonDocument("cuisine", "French")),
        new BsonDocument("$unset", "borough")
    )
);
await _restaurantsCollection.UpdateOneAsync(filter, updatePipeline);

Configuration Options

The UpdateOne() and UpdateOneAsync() methods optionally accept an UpdateOptions object as a parameter. You can use this argument to configure the update operation.

The UpdateOptions class contains the following properties:

Return Value

The UpdateOne() method returns an UpdateResult, and the UpdateOneAsync() method returns a Task<UpdateResult> object. The UpdateResult class contains the following properties:

Additional Information

For runnable examples of the update operations, see the following usage examples:

• UpdateOne()

• UpdateOneAsync()

To learn more about creating query filters, see the Create a Query Filter guide.

Sample Class

The code examples in this guide demonstrate how you can use builders to create types to interact with documents in the sample collection plants.flowers. Documents in this collection are modeled by the following Flower class:

public class Flower
{
    public ObjectId Id { get; set; }
    public string Name { get; set; }
    public string Category { get; set; }
    public double Price { get; set; }
    public List<string> Season { get; set; }
    public double Stock { get; set; }
    public string Description { get; set; }
}

Each builder class takes a generic type parameter TDocument which represents the type of document that you are working with. In this guide, the Flower class is the document type used in each builder class example.

Define an Update

The UpdateDefinitionBuilder class provides a type-safe interface for building up an update specification. Suppose you want to create an update specification with the following criteria:

• Create the new field SunRequirement

• Multiply the Price field value by 0.9

Use builders to create the update specification with the typed variant:

var builder = Builders<Flower>.Update;
var update = builder.Set(f => f.SunRequirement, "Full sun").Mul(f => f.Price, 0.9);

Alternatively, you can use string-based field names to define the update:

var builder = Builders<Flower>.Update;
var update = builder.Set("SunRequirement", "Full sun").Mul("Price", 0.9);

• UpdateDefinitionBuilder