Validation: support placeholders for anything

[element-code]

This fixes #3774

Checklist:

• Securely signed commits
• Component(s) with PHPdocs
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[paulbalandan]

This needs a couple of tests.

[MGatner]

@element-code I'm afraid I don't understand either the problem or the solution. Could you either provide some tests or elaborate more on what the issue is and how your PR fixes it?

[element-code]

@MGatner the issue pops up when applying rules.
I'm not sure which cases are affected, and I don't have time right now to check it back, but the following cases to apply rules are valid and should work -- some of them do not work.
What i definetely fixed is case F, I don't know how the other cases behave, my guess is that A-D are fine and E & F are not working -- maybe I'm wrong and A, C, E are working and B, D, F are not :D .
Cases A, C and E are working, B and F are not working (and fixed) and case D is invalid.
My solution is always splitting them down to arrays to the lowest allowed level and go on from there.
Watch out, a rule can also be an array ['customRule', function(){]] as taken into account here.

A setRule (string)

setRule('foo', 'required|filter[{placeholder}]')

B setRule (array)

setRule('foo', ['required', 'filter[{placeholder}]'])

C setRules (simple, string)

setRules([
  'foo' => 'required|filter[{placeholder}]'
])

D setRules (simple, array) (invalid rule collection format)

setRules([
  'foo' => ['required', 'filter[{placeholder}]']
])

E setRules (complex, string)

setRules([
  'foo' => [
    'rules' => 'required|filter[{placeholder}]'
  ]
])

F setRules (complex, array)

setRules([
  'foo' => [
    'rules' => ['required', 'filter[{placeholder}]']
  ]
])

[MGatner]

Thank you, a very good explanation and examples. It strikes me that your examples are pretty much just the test cases we need. Would you be willing to add those to the Validation Tests so we can get this PR reviewed and merged?

[element-code]

Jup, i still didnt write any tests and therefore have no experience with tests. Planning this for next week.
It would be nice if you could provide me with one positive and one negative test-case-implementation -- replicating code is much easier than finding out hot tf tests work :D .
In case you plan to do that, then PR branch should be open to public for pushes.

[element-code]

@MGatner @paulbalandan any news on this?

[MGatner]

Any style issues will be caught when we apply 4.2 to develop.

Please update user_guide_src/source/libraries/validation.rst and then I think this is good!

[element-code]

@MGatner done

[MGatner]

3 files changed

Still not seeing it! Did you mix up branches perhaps?

[element-code]

@MGatner uhm, could you explain what you are expecting?
Im sorry, I just saw the conflict with 4.2 so I merged the updates.

[MGatner]

I'm on mobile so I'm having a hard time seeing the whole thing but that file has some references to the old method signature that needs updating. For example:

setRule()
...
It takes the name of the field as
the first parameter, an optional label and a string with a pipe-delimited list of rules
that should be applied

Just scan through the file and make sure anything you changed is updated and any new features are explained properly.

[paulbalandan]

@MGatner can you check on this one?

[kenjis]

It seems the base branch of this PR must be changed to develop.

[kenjis]

@element-code It seem this PR need to be rebased.
https://github.com/codeigniter4/CodeIgniter4/blob/develop/contributing/workflow.md#pushing-your-branch

Could you?

[lonnieezell]

@kenjis @paulbalandan Do either of you want to champion this one enough to rebase it and fix any conflicts or should we close it?