Writing update statements

To update complex items, you may have to write more complex update expressions than just providing the new value. For that, use set operators.

Using arithmetic set operators

The following arithmetic set operators are available:

Operator	Description
`$decrementBy`	Decreases the field by the given value.
`$divideBy`	Divides the field by the given value.
`$incrementBy`	Increments the field by the given value.
`$multiplyBy`	Multiplies the field by the given value.

E.g., to increase the printCount field of an invoice, use the following code:

invoices.update({
  where: { id: event.aggregate.id },
  set: { printCount: { $incrementBy: 1 }}
});

The following array set operators are available:

Operator	Description
`$add`	Adds the given value to the array.
`$remove`	Removes the given value from the array.

E.g., to remove the tag private from all invoices that contain this tag, use the given code:

invoices.update({
  where: { tags: { $contains: 'private' }},
  set: { tags: { $remove: 'private' }}
});