Preventing lost updates in Symfony APIs with ETags and Doctrine

There is a concurrency problem in APIs that is easy to miss. Two clients read the same resource: Client A -> GET /documents/42 Client B -> GET /documents/42 Both receive the same version. Client A changes the title and saves it.

Source: [Dev.to](https://dev.to/alkin/preventing-lost-updates-in-symfony-apis-with-etags-and-doctrine-1h57)