Old reducers still re-run

[Siyfion]

I think this might be related to #960 or potentially #930 but it's not the same as either.

I believe that the issue is caused by "old" reducers still being re-run even though they are marked as old, causing a "double" (or more) firing of the event.

Symptoms:

I have a component that is created when the user navigates to a particular route, if I delete an item on that page the reducer fires once and updates the query's previous result and removed the deleted item from the results set.
If I leave that route (unmounting the component) and re-enter it again, upon deletion the reducer will fire twice, attempting to remove the result twice. As I hadn't originally foreseen the item never being there, the _.findIndex call returned -1 on the second trigger then removed a second item (one that actually hadn't been deleted!).

I've mentioned this to @helfer and he suggested making an issue here..

[helfer]

@Siyfion can you test if this is fixed now?

[Siyfion]

@helfer Just tested with apollo-client v0.5.19 and no... This isn't fixed.

[helfer]

@Siyfion okay, in that case I will need a bit more information, ideally a minimal reproduction or a failing test case.

[Siyfion]

@helfer I don't really know how best to provide a reproduction, but a simple component like: https://gist.github.com/Siyfion/fa29549a77111f017efd9413ff32c04b

And a simple toggle switch that removes / adds the component with each click is enough to demonstrate the issue. For each additional X times the component is created the reducer function will run X times (when triggered).

[SachaG]

I can confirm I'm running into the same issue. I have a list of posts on my homepage, and inserting posts into it works fine.

But if I go to another page (which unmounts the post list), come back, and try inserting again, I get a Encountered two children with the same key React error because the new document was inserted twice. And if I got back and forth 5 extra times, I'll now have 5 extra documents in my list (and thus 5 errors).

If you want to test it out you can pull the latest version of Nova: https://github.com/TelescopeJS/Telescope/tree/apollo

[helfer]

Should be fixed in 0.5.22.

[SachaG]

Awesome, thanks so much!