Laravel Collection Public API: diff_keys

diffKeys($items)

The diffKeys method is similar to the diff method. It is used to determine which items whose keys in the collection are not present in the supplied $items collection's keys. $items can be either an array, or another instead of Collection.

The following example shows the basic usage of the diffKeys method:

1<?php
2 
3$firstCollection = collect(['name' => 'Shiny New Tablet', 'price' => 799.99]);
4$secondCollection = collect(['name' => 'Shiny New Tablet', 'description' => 'Much shinier and bigger!']);
5 
6$differences = $firstCollection->diffKeys($secondCollection);

After the code has executed the $differences variable would contain a value similar to the following:

1Collection {
2  #items: array:1 [
3    "price" => 799.99
4  ]
5}

The result only contains the item price, because that is the only item in the $firstCollection that was not present in the $secondCollection.

If we had reversed the order of the collections to the following:

1<?php
2 
3$firstCollection = collect(['name' => 'Shiny New Tablet', 'price' => 799.99]);
4$secondCollection = collect([
5    'name' => 'Shiny New Tablet',
6    'description' => 'Much shinier and bigger!'
7]);
8 
9$differences = $secondCollection->diffKeys($firstCollection);

this would be the value returned:

1Collection {
2  #items: array:1 [
3    "description" => "Much shinier and bigger!"
4  ]
5}

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