Laravel 5 Collections: Retrieving Collection Elements Whose Keys Are Not Present in the Provided Keys With diffKeys

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.

#Signature

1public function diffKeys(
2    $items
3);

#Example Use

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

 1$firstCollection = collect([
 2    'name' => 'Shiny New Tablet',
 3    'price' => 799.99
 4]);
 5 
 6$secondCollection = collect([
 7    'name' => 'Shiny New Tablet',
 8    'description' => 'Much shinier and bigger!'
 9]);
10 
11$differences = $firstCollection
12                ->diffKeys($secondCollection);

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

1Collection {
2  #items: array [
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$firstCollection = collect([
 2    'name' => 'Shiny New Tablet',
 3    'price' => 799.99
 4]);
 5 
 6$secondCollection = collect([
 7    'name' => 'Shiny New Tablet',
 8    'description' => 'Much shinier and bigger!'
 9]);
10 
11$differences = $secondCollection
12                ->diffKeys($firstCollection);

this would be the value returned:

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

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