Write

A write on a document.

JSON representation 
{
  "updateMask": {
    object (DocumentMask)
  },
  "updateTransforms": [
    {
      object (FieldTransform)
    }
  ],
  "currentDocument": {
    object (Precondition)
  },

  // Union field operation can be only one of the following:
  "update": {
    object (Document)
  },
  "delete": string,
  "transform": {
    object (DocumentTransform)
  }
  // End of list of possible types for union field operation.
}
Fields
updateMask

object (DocumentMask)

The fields to update in this write.

This field can be set only when the operation is update. If the mask is not set for an update and the document exists, any existing data will be overwritten. If the mask is set and the document on the server has fields not covered by the mask, they are left unchanged. Fields referenced in the mask, but not present in the input document, are deleted from the document on the server. The field paths in this mask must not contain a reserved field name.
updateTransforms[]

object (FieldTransform)

The transforms to perform after update.

This field can be set only when the operation is update. If present, this write is equivalent to performing update and transform to the same document atomically and in order.
currentDocument

object (Precondition)

An optional precondition on the document.

The write will fail if this is set and not met by the target document.
Union field operation. The operation to execute. operation can be only one of the following:
update

object (Document)

A document to write.
delete

string