Laravel 5.7. Subtract model instances

Question

I have 2 collections of models.

For example

$full = collect([
    [
        'name' => 'name1',  //id was omitted intentionally
    ],
    [
        'name' => 'name2', //id was omitted intentionally
    ],
    [
        'name' => 'name3', //id was omitted intentionally
    ],
]);

$diff = collect([
    [
        'id'   => 6,
        'name' => 'name1',
    ],
]);

and I want to receive such a result after something like this

$full->diff($full);

$result = [
    [
        'name' => 'name2',
    ],
    [
        'name' => 'name3',
    ],
];

How to achieve that without filter() or reject() with contains() in a neater way?

I'm confused, you want a collection to take itself on a ->diff() method call and return part of itself back? what logic do you want it to use to decide what to return? — wheelmaker, Sep 15 '18 at 20:57
Why would a diff return `name1`? Wouldn't you want `name2` and `name3`? — ourmandave, Sep 15 '18 at 21:43
@mattQuest Probably I do not understand something in the 'diff' method, but I've written what I want to receive. Just subtract $diff from $full. How to achieve that? What function should I use? — D.R., Sep 15 '18 at 21:53
I think I got it... did you intend to put the $diff var in $full->diff($diff) instead of $full->diff($full). Also, did you intend to put 'name3' in the $diff collection? — wheelmaker, Sep 15 '18 at 21:56
I've tried both ways to call `diff()`. None worked out for me)) — D.R., Sep 15 '18 at 22:15
I'm using `reject()` now, but is there any shorted way to do that? — D.R., Sep 15 '18 at 22:19

score 2 · Answer 1 · answered Sep 15 '18 at 22:31

2

It's hard to say why you don't want to use filter or reject with contains but there is another solution:

$result = $full->pluck('name')->diff($diff->pluck('name'))->map(function($name) {
        return [
            'name' => $name
        ];
    });

dd($result->toArray());

As result you will get:

array:2 [▼
  1 => array:1 [▼
    "name" => "name2"
  ]
  2 => array:1 [▼
    "name" => "name3"
  ]
]

answered Sep 15 '18 at 22:31

Marcin Nabiałek

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Just cause I was searching for a one-line solution, cause this is quite a common task) – D.R. Sep 15 '18 at 22:33
This should be made an answer because I couldn't fine any shorter solution – Fariz Luqman Sep 25 '20 at 09:16

score 1 · Answer 2 · answered Sep 15 '18 at 22:19

1

The diff method should work as needed with a new collection containing just the name property:

$comparableDiff = $diff->pluck('name');
$result = $full->diff($comparableDiff);

answered Sep 15 '18 at 22:19

wheelmaker

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But what if I need to perform the same logic for models based on one `name` key?) I've mentioned it, but couldn't show in a simple code example) – D.R. Sep 15 '18 at 22:21
as long as your "$full" collection and "$diff" collection have the same properties (ie: collections of the same model) it should work – wheelmaker Sep 15 '18 at 22:24
Hm..are you sure? Cause it's not working in my case. – D.R. Sep 15 '18 at 22:28
And I receive all items. – D.R. Sep 15 '18 at 22:31

score 0 · Accepted Answer · answered Sep 15 '18 at 22:35

0

I haven't found a neater approach than

$profiles->reject(function ($profile) use ($existingProfiles) {
    return $existingProfiles->pluck('name')->contains($profile->name);
})->values()

But thanks to everyone. I've upvoted your questions ;)

answered Sep 15 '18 at 22:35

D.R.

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But this is not what you asked :) You wanted solution without using `reject` and `contains` :) – Marcin Nabiałek Sep 16 '18 at 07:02
I should have written "that is neater"))) Sorry for not specifying that. Just, you know, we, devs, always aiming for perfection) – D.R. Sep 16 '18 at 13:55

Laravel 5.7. Subtract model instances

3 Answers3