prevent throw array access error when orderByChild('nested/key')

[llstarscreamll]

This PR prevent throw array access errors when use nested Firebase paths on orderByChild. Look at the next query example:

$firebase->getReference('users')
  ->orderByChild('profile/email') // nested Firebase path
  ->startAt('john@')
  ->getValue();

The schema:

"users": {
  "a1": {
    "profile": {
      "email": "[email protected]"
     }
  }
}

Before this throwed [ErrorException] Undefined index: profile/email.

Now this query doesn't throw exceptions.

[jeromegamez]

Thank you for the contribution! I didn't even know it was possible to order by a nested child value - is it? And if so, why isn't it documented in the official docs 😅?

I will have a deeper look at it shortly - I will certainly rework the helper method, because I think it could be structured a lot nicer (and code climate agrees 😅), but I will make sure that your commits are preserved.

[llstarscreamll]

Hi @jeromegamez, I have been very busy these days, I made a small cleaning up and renamed the helper method, all is green now, make the modifications you consider to this PR.

Thank you so much for this library!!

Cheers!!

[jeromegamez]

Thank you Johan! The reason why it's taking me so long to review and integrate this feature is that I have to understand what's happening and to be sure that it's the best and easiest possible way to provide a feature (as it's me who has to provide support for the library in the future :)).

I do understand what's happening and why this is needed, but my gut tells me that there's an easier way to do it ^^. Your PR will be merged and you'll get attributed for the feature, please allow me a little bit more time for it :). Cheers!

[jeromegamez]

Hey Johan! Thanks again for your contribution - please have a look at Release 3.7.0 - it includes your contribution and the changes I made based upon your work:

• Added tests to ensure that everything is working as expected (it did with your solution)
• Used Jmespath to check for the nested values - the library is already included in the SDK and provides a similar functionality to the one you provided.

Cheers!

[llstarscreamll]

Great!! Thank you so much!!