Prevent overwriting instock when saving an article in the backend

[fixpunkt]

We think that this process causes instock errors:

1. Open article detail view.
2. Article gets ordered, which decreases the instock.
3. Save the article view.

• Verify that this is actually the case
• Make a PR
• Monkey-patch into Shopware from ERP.

[maximilianoster]

I just add the reference to https://github.com/VIISON/ShopwarePickwareERP/issues/383#issuecomment-278656645 as we already discussed the problem and a possible solution there.

[samuelvogel]

We already "monkey-patched" this in Shopware ERP powered by Pickware plugin.

We also want to have something similar for customer orders and also Pickware supplier orders. For articles it's just the easiest, since the field changetime is already present is s_articles (but it's not always updated yet, especially not when frontend orders change the instock).

[windaishi]

I would do anything for Pickware, but I won't do that...
(Actually I already did the SW pull request for this shopware/shopware#1474)

[fixpunkt]

Actually, I don't think the case described in this issue is actually fixed by shopware/shopware#1474. Have you tested that?

[windaishi]

Okay, I started an instance and tested the article overwrite protection. Since the protection currently only works only for s_article and not s_article_details, the protection is not triggered in that case.
Therefore we need a timestand on a s_article_details level.
Since this is monkey patched in ERP already, this is only a problem in the plain SW installation.