Exception in idempotent PUT request?

Question

I have an issue with implementing Idempotent operation in Put.

There is Put request which updates a field in a rest API resource.

But to implement Idempotency every repeated request should result in same state of the object.

We use a database what happens if an error occurs. Now does this mean Idempotency is lost? if not

Now going by the same defintion - If we have a conditional status change in a rest API on a field .eg) status field.

If the logic is to update the status field only if the parent property field locked==false, we can throw an exception saying 'BusinessLogic exception cannot update status'

So in theory we have two operations we have similar situation:

1. one could be idempotent if not for real life errors which cannot be avoided
2. One should not be idempotent but we can make it similar

question:

How do you implement error handling based idempotency for put? and if error handling is OK does this mean even business logics could be made idempotency Put?

Answer 1

It may help to review the relevant definition of idempotent

We use a database what happens if an error occurs. Now does this mean Idempotency is lost?

Idempotency is not lost. Idempotent doesn't promise that every request will succeed; it only means that any loss of property that occurs because the server received multiple copies of the request is the fault of the server.

does this mean even business logics could be made idempotency Put?

Yes. You can do this in one of two ways: by designing your domain application protocol so that the requests are inherently idempotent; or by using conditional requests to describe the "before" state that the request is intending to change.