update-many

For the complete MongoDB documentation index, see www.mongodb.com/docs/llms.txt

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Update Many

Overview

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

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

• UpdateMany(): Updates one or more fields in multiple documents.

• UpdateManyAsync(): The asynchronous version of UpdateMany().

The following sections describe these methods in more detail.

Note: Method Overloads

Many of the methods on this page have multiple overloads. The examples in this guide show only one definition of each method. For more information about the available overloads, see the API documentation.

Important: Input Validation

Builder classes and LINQ queries pass values to the underlying MongoDB operation. By design, these APIs are not a security sanitization layer. Validate and sanitize untrusted input in your application before you pass it to a builder or a LINQ query.

Sample Data

The examples in this guide use the restaurants collection from the sample_restaurants database. The documents in this collection use the following Restaurant, Address, and GradeEntry classes as models:

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; }
}

Note:

The documents in the restaurants collection use the snake-case naming convention. The examples in this guide use a ConventionPack to deserialize the fields in the collection into Pascal case and map them to the properties in the Restaurant class.

To learn more about custom serialization, see [Custom Serialization.](https://www.mongodb.com/docs/drivers/csharp/current/serialization/poco.md#std-label-csharp-custom-serialization

This collection is from the sample datasets provided by Atlas. See the [Get Started with the .NET/C# Driver](https://www.mongodb.com/docs/drivers/csharp/current/get-started.md#std-label-csharp-get-started to learn how to create a free MongoDB cluster and load this sample data.

Methods and Parameters

The UpdateMany() and UpdateManyAsync() methods accept the following parameters:

Update Multiple Values

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

Combined Update Definitions

The Builders.Update.Combine() method lets you combine multiple UpdateDefinition objects. This method accepts the following parameter:

The Combine() method returns a single UpdateDefinition object that defines multiple update operations.

The following code example uses the Combine() method to combine a [$set](https://www.mongodb.com/docs/manual/reference/operator/update/set/#mongodb-update-up.-set operation and an [$unset](https://www.mongodb.com/docs/manual/reference/operator/update/unset/#mongodb-update-up.-unset operation:

UpdateMany (Sync)

var filter = Builders<Restaurant>.Filter
    .Eq("cuisine", "Pizza");

var combinedUpdate = Builders<Restaurant>.Update.Combine(
    Builders<Restaurant>.Update.Set("cuisine", "French"),
    Builders<Restaurant>.Update.Unset("borough")
);

_restaurantsCollection.UpdateMany(filter, combinedUpdate);

Update Pipelines

You can join a sequence of update operations into a single aggregation pipeline.

To create an update pipeline, call the Builders.Update.Pipeline() method. This method accepts the following parameter:

The Pipeline() method returns a single UpdateDefinition object that defines multiple aggregation stages.

The following code example uses the Pipeline() method to combine a [$set](https://www.mongodb.com/docs/manual/reference/operator/update/set/#mongodb-update-up.-set operation and an [$unset](https://www.mongodb.com/docs/manual/reference/operator/update/unset/#mongodb-update-up.-unset operation:

UpdateMany (Sync)

var filter = Builders<Restaurant>.Filter
    .Eq("cuisine", "Pizza");

var updatePipeline = Builders<Restaurant>.Update.Pipeline(
    PipelineDefinition<Restaurant, Restaurant>.Create(
        new BsonDocument("$set", new BsonDocument("cuisine", "French")),
        new BsonDocument("$unset", "borough")
    )
);

_restaurantsCollection.UpdateMany(filter, updatePipeline);

Note: Unsupported Operations

Update pipelines don't support all update operations, but they do support certain aggregation stages not found in other update definitions. For a list of update operations supported by pipelines, see Updates with Aggregation Pipeline in the MongoDB Server manual.

Configuration Options

The UpdateMany() and UpdateManyAsync() 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:

Collation

To configure collation for your operation, create an instance of the Collation class.

The following table describes the parameters that the Collation constructor accepts. It also lists the corresponding class property that you can use to read each setting's value.

For more information about collation, see the Collation page in the MongoDB Server manual.

Return Value

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

Additional Information

This page includes a short interactive lab that demonstrates how to modify data by using the UpdateManyAsync() method. You can complete this lab directly in your browser window without installing MongoDB or a code editor.

To start the lab, click the Open Interactive Tutorial button at the top of the page. To expand the lab to a full-screen format, click the full-screen button (⛶) in the top-right corner of the lab pane.

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

• UpdateMany()

• UpdateManyAsync()

To learn more about creating query filters, see the [Create a Query Filter](https://www.mongodb.com/docs/drivers/csharp/current/crud/query/query-filter.md#std-label-csharp-specify-query guide.

API Documentation

For more information about any of the methods or types discussed in this guide, see the following API documentation:

• UpdateOne()

• UpdateOneAsync()

• UpdateOptions

• UpdateResult