Fix forceId to reject empty strings

[Yaty]

Status : WIP

Description

Add allowBlank and allowNull opions to validatesAbsenceOf
Make allowBlank and allowNull to false when forceId if set to true

My test are passing but I broke other tests like this one : https://github.com/strongloop/loopback-datasource-juggler/blob/1ef38a6929ae100c73030b720097ba5c4b90a7b3/test/optional-validation.test.js#L117
It seems that the validation is made before the ID is generated so it breaks.
This is the first time I'm working on this codebase, any tips where I should look :) ?

Related issues

#1519

Checklist

• New tests added or existing tests modified to cover all changes
• Code conforms with the style
  guide

[slnode]

Can one of the admins verify this patch? To accept patch and trigger a build add comment ".ok\W+to\W+test."

[jannyHou]

@slnode test please

[nitro404]

It would probably be beneficial to squash or amend these commits together as they both seem to have the same message, and is a bit confusing, unless there is some reason to keep them separate.

[bajtos]

Hello @Yaty, thank you for the pull request. The proposed changes look reasonable to me, we need to polish the edge cases now.

My test are passing but I broke other tests like this one

I think this is a sign that your change will probably break existing applications. IIUC, the intention is to reject null and empty strings. However, we must still allow undefined as a valid (and required!) value.

Perhaps nullCheck treats undefined the same way as null?

[bajtos]

Closing as abandoned. Feel free to reopen if you get time to work on it again.