Laravel Eloquent unique() - Seems to not work

Question

I'm using Laravel Eloquent to pick out unique answers.

So in my Database I have 3 answers, But they are under two different questions.

So all I would need returning back is the number 2, Not the number 3.

My code so far is :

$foundation_scores = Foundation::where('user_id', $this->user_id)
                                       ->where('foundation_section', 'theory')
                                       ->get();

        $foundation_scores->unique('foundation_question');
        $foundation_scores = count($foundation_scores);

The unique('foundation_question') is returning 3. It should return 2

Any ideas why this would be?

My collection looks as follows (NOTE) I've outputted it as an array to avoide all the code Laravel Returns :

array:3 [
  0 => array:12 [
    "foundation_id" => 3
    "user_id" => 17019
    "foundation_section" => "theory"
    "unit_id" => 0
    "foundation_sub_section" => "Unit 1"
    "foundation_question" => 0
    "foundation_reference" => "Ref one way st"
    "foundation_answer" => "Ref answer st"
    "created_at" => "2017-10-25 11:57:05"
    "updated_at" => "2017-10-25 11:57:05"
    "deleted_at" => null
    "friendly_date" => "25th October 2017"
  ]
  1 => array:12 [
    "foundation_id" => 4
    "user_id" => 17019
    "foundation_section" => "theory"
    "unit_id" => 0
    "foundation_sub_section" => "Unit 1"
    "foundation_question" => 0
    "foundation_reference" => "Red"
    "foundation_answer" => "Ans"
    "created_at" => "2017-10-25 12:02:01"
    "updated_at" => "2017-10-25 12:02:01"
    "deleted_at" => null
    "friendly_date" => "25th October 2017"
  ]
  2 => array:12 [
    "foundation_id" => 5
    "user_id" => 17019
    "foundation_section" => "theory"
    "unit_id" => 0
    "foundation_sub_section" => "Unit 1"
    "foundation_question" => 1
    "foundation_reference" => "XY"
    "foundation_answer" => "Z"
    "created_at" => "2017-10-25 12:02:19"
    "updated_at" => "2017-10-25 12:02:19"
    "deleted_at" => null
    "friendly_date" => "25th October 2017"
  ]
]

Is their a bug with unique. Or is it something I'm doing wrong?

Answer 1

$foundation_scores->unique('foundation_question'); is not assigning unique values to any new variable. Also unique() does not change original collection.

So:

$unique_collection = $foundation_scores->unique('foundation_question');
echo count($unique_collection);