How can I validate that I am passing an Asset into my custom twig filter?

Question

I'm creating a custom twig filter in Craft 3 and am struggling with a really simple thing.

{{ entry.backgroundImage.one() | filter }}

In my filter, I would like to validate that I am being passed an asset.

if (!$asset instanceof Asset)
{
    return false;
}

What should I be checking the object against? Asset or something different?

andrew.welch · Accepted Answer · 2018-07-22 17:56:12Z

3

Actually, you had your code just right imo:

use craft\elements\Asset;

...

if (!$asset instanceof Asset) {
    return false;
}

answered Jul 22 '18 at 17:56

andrew.welch

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looks like I forgot use craft\elements\Asset; which would have made the original code work. Thanks! – kisonay Jul 22 '18 at 20:41
I think doing it this way is a good bit cleaner – andrew.welch Jul 23 '18 at 0:50
I actually agree that this is probably the cleaner solution. In comparing get_class and instanceof, a useful detail to know is that instanceof will also return true for a class extending the class you're testing against (i.e. your conditional will evaluate to true if you pass it an object w/ a class extending Asset, which may or may not be what you want), where get_class($object) === 'SomeClass' will only evaluate to true if the object actually has that particular class. In this case, I'm fairly positive it doesn't matter and both approaches will work. – Mats Mikkel Rummelhoff Jul 23 '18 at 8:38
Also, instead of hard coding the full, namespaced classname, it's also possible to do use craft\elements\Asset; ... if (\get_class($asset) === Asset::class) { ... of course :) – Mats Mikkel Rummelhoff Jul 23 '18 at 8:39
That is a great callout @MatsMikkelRummelhoff, great to know that this will also acknowledge exertions. In light of this, I've mad this the correct answer. – kisonay Jul 23 '18 at 11:36

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Mats Mikkel Rummelhoff · Accepted Answer · 2018-07-22 15:20:52Z

2

Assuming you're using Craft 3, this should work:

if (\get_class($asset) !== 'craft\elements\Asset) {
    return false;
}

answered Jul 22 '18 at 14:58

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