UpdateDescription

A document containing key:value pairs of names of the fields that were changed (excluding the fields reported via truncatedArrays), and the new value for those fields.

Despite array fields reported via truncatedArrays being excluded from this field, changes to fields of the elements of the array values may be reported via this field.

Example: original field: “arrayField”: [“foo”, {“a”: “bar”}, 1, 2, 3] updated field: “arrayField”: [“foo”, {“a”: “bar”, “b”: 3}] a potential corresponding UpdateDescription: UpdateDescription( updatedFields: { “arrayField.1.b”: 3 }, removedFields: [], truncatedArrays: [ TruncatedArrayDescription( field: “arrayField”, newSize: 2 ) ] )

Modifications to array elements are expressed via dot notation. Example: an update which sets the element with index 0 in the array field named arrayField to 7 is reported as “updatedFields”: {“arrayField.0”: 7}

An array of field names that were removed from the document.

Describes an array that was truncated via an update operation.

Truncations of arrays may be reported either via this field or via the ‘updatedFields’ field. In the latter case, the entire array is considered to be replaced. The method used to report a truncation is a server implementation detail.

Example: an update which shrinks the array arrayField.0.nestedArrayField from size 8 to 5 may be reported via this field as [TruncatedArrayDescription(field: “arrayField.0.nestedArrayField”, newSize: 5)].

This property will only ever be present on MongoDB server versions >= 5.0.