📝Update

Overview

MongoDB provides a set of update operators to help you update values on your collections' documents. This section contains several samples showing how to use these operators to update:

• Top level fields

• Embedded fields

• Array fields

Complex update operations such as updating embedded fields, adding or removing items in embedded array fields might be straight forward when building the queries in the Shell but not so much when using the MongoDB C# driver

The section contains samples for the following operators:

Operator	Description
Set	Sets the value of a field in a document
Inc	Increments a field's value
Min	Updates a field's value only if the specified value is less than the existing
Max	Updates a field's value only if the specified value is greater than the existing
Mul	Multiplies a field's value by a specified amount
Unset	Removes the specified field from the document
Rename	Renames a field

Other than the update operations there are also samples showing how to replace documents and array fields.

Update Definition Builder 💪

To create update operations using the MongoDB C# driver you need to create one or more update definitions. The syntax to create an update definition is the following:

Syntax: Builders<T>.Update.<Operator>(<field>,<value>)

🧙 An update definition can be the result of more than 1 update definitions on the same document which means you can build a query that updates multiple fields using different operators.

Here's' an example:

var multiUpdateDefinition = Builders<User>.Update
    .Set(u => u.Phone, "123-456-789") // update 1
    .Inc(u => u.Salary, 300) // update 2
    .Set(u => u.FavoriteSports, 
        new List<string> 
        { "Soccer", "Basketball" }); // update 3

UpdateOne & UpdateMany

To update one or more documents use the UpdateOne and UpdateMany IMongoCollection<T> respectively.

Syntax: IMongoCollection<T>.UpdateOne(<filter>,<update-definition>)

Syntax: IMongoCollection<T>.UpdateMany(<filter>,<update-definition>)

Update methods return information ℹ️regarding total documents matched by the filter, total documents modified and if there was acknowledgement

{
	"acknowledged" : true,
	"matchedCount" : 1,
	"modifiedCount" : 1
}