699687 - Provide friendlier error for 409 "unsaved value mapping" error

Status: RESOLVED FIXED

(Mozilla QA Graveyard :: MozTrap, defect)

Description

[Carl Meyer (:carljm)]

Although we have had some UI caching bugs that caused this error to appear spuriously, this is also a platform error users are bound to hit occasionally in multi-user use (or even single-user, mult-tab use). Basically it means that the UI attempted to modify an object in the platform, but submitted an out-of-date originalVersionId - in other words, the object has been modified by "someone else" in the meantime. So we should really at least provide a nicer error message that alerts the user to this situation.

Comment 1

[Cameron Dawson [:camd]]

A Pivotal Tracker story has been created for this Bug: http://www.pivotaltracker.com/story/show/20576689

Comment 2

[Cameron Dawson [:camd]]

Carl Meyer added a comment in Pivotal Tracker:   
   
Actually, I was wrong here. Because each request fetches a fresh version of whatever object is being edited or deleted, it would be very rare for a user to actually hit this error.

This also means that we don't have the protection against edit overwrites - if two users open the same edit page, whoever saves first will see their changes overwritten by whoever saves second. This is something we may want to address, but at this point we should do it after the switch to pure Django.

Anyway, I went ahead and put in the nicer error message for this, but it's pretty hard to verify as there's no reliable way to generate the error that I know of - it would only occur if two users saved the same object at almost the same instant.

Comment 3

[Cameron Dawson [:camd]]

Carl Meyer changed story state to finished in Pivotal Tracker

Comment 4

[Cameron Dawson [:camd]]

Carl Meyer changed story state to delivered in Pivotal Tracker

Comment 5

[Cameron Dawson [:camd]]

Carl Meyer changed story state to delivered in Pivotal Tracker

Comment 6

[Cameron Dawson [:camd]]

Cameron Dawson changed story state to accepted in Pivotal Tracker