Fix comparing arrays with entity references

[boudewijn-zicht]

When the values are empty arrays we do NOT use Hash::check because that will always return false, hence even when both values are empty arrays the result will still be that the values are different and have to be imported

Fixes #1238

[angrybrad]

@boudewijn-zicht not sure i'm following this one - could you give an example of the two types of arrays that are being compared here?

ids as "most likely elements" feels a bit weird, too - are there cases where they are legitimate, non-element-id integers?

[boudewijn-zicht]

@boudewijn-zicht not sure i'm following this one - could you give an example of the two types of arrays that are being compared here?

ids as "most likely elements" feels a bit weird, too - are there cases where they are legitimate, non-element-id integers?

I will try to clarify with an example:

1. your Craft installation has two sections, 'Page' and 'Item'. The page has an element field 'Items', i.e. a page can have multiple items.
2. When you import pages you can also import these relations (i.e. using the item title or whatever).
3. The import tries to see if a page already has the item relations that it is trying to import/update by comparing $firstValue and $secondValue.
4. These values are numbers, presumably the element ids of the Items
5. Unfortunately $firstValue and $secondValue have keys that do not match, i.e. one may be [0=>123, 1=>456] and the other might be [0=123, 2=>456].

This PR checks that all values in both $firstValue and $secondValue are numbers and then normalizes their keys to ensure that the comparison results in 'yes, they are the same'.

[angrybrad]

Resolved in 9c272ab