Fix migration on added duplicated container settings

[yurabakhtin]

What kind of change does this PR introduce? (check at least one)

• Bugfix

The PR fulfills these requirements:

• It's submitted to the develop branch, not the master branch if no hotfix
• All tests are passing
• Changelog was modified

Other information:
https://github.com/humhub/humhub-internal/issues/246

[luke-]

@marc-farre FYI

[marc-farre]

Interesting, I wouldn't have thought about this eventuality, thanks for mentioning me.

@yurabakhtin Thanks for the fix!
Does it mean we should always check if the database is not already updated before applying a migration? E.g., if we add a column, we should check if it doesn't already exist?

[yurabakhtin]

@yurabakhtin Thanks for the fix!
Does it mean we should always check if the database is not already updated before applying a migration? E.g., if we add a column, we should check if it doesn't already exist?

@marc-farre Your change is not related to a creating of new column, there was an issue related to duplicated records with unique index, really it shouldn't have happened for a normal migration call, it seems it happened because 2 migration processes were called twice ata the same time, that should be fixed from core side, I will review the code soon.

However for adding new column we should use humhub\components\Migration and methods like safeAddColumn(), safeCreateTable() and etc. which already check it for existing before a creating, instead of yii\db\Migration and addColumn().

[marc-farre]

@yurabakhtin Thanks.

@luke- I've added @yurabakhtin recommendations in the doc via the PR humhub/documentation#122