PHP get Array with sub Array from SQL - php

Question

I am new with coding and I just can't seem to get my head around this. A little help or tip is much appreciated.
Basically I want an array with Questionnaires, which consist of id, name and a sub array of questions. Questions also consist of id and name.(1 Questionnaire can have multiple questions)
Something like this is what I am looking for:
[{Questionnaires{id:x, name:x, questions:{id:x, name:x},{id:x2, name:x2}}]
This is my query
SELECT questionnaires.id QuestionnaireId, questionnaires.title QuestionnaireTitle, questions.id QuestionId, questions.text Question
FROM questionnaires INNER JOIN questionnaireshasquestions qa ON qa.idQuestionnaire = questionnaires.id
INNER JOIN questions ON questions.id = qa.idQuestion
And my PHP Code:
while ($row = $conn->fetch()) {
if (!isset($data['questionnaires'][$row['QuestionnaireId']])) {
$data['questionnaires'][] = array(
'id' => $row['QuestionnaireId'],
'title' => $row['QuestionnaireTitle'],
'questions' => array(
'id' => $row['QuestionId'],
'text' => $row['Question']
)
);
} else {
$data['questionnaires'][$row['QuestionnaireId']][] = array(
'questions' => array(
'id' => $row['QuestionId'],
'text' => $row['Question']
)
);
}
The JSON array I get with this is in a wrong/incorrect format:
{"questionnaires":[{"id":"1","title":"Are you hungry?","questions":{"id":"1","text":"How is your passion? "}},{"id":"1","title":"Are you hungry?","questions":{"id":"2","text":"Do you drink?"}},{"id":"2","title":"How are you feeling?","questions":{"id":"1","text":"How is your passion? "},"0":{"questions":{"id":"3","text":"Do you like fish?"}}},{"id":"5","title":"Is testing working?","questions":{"id":"4","text":"How is the testing?"}}]
As you can see, it repeats the same Questionnaire for each Question within...
I hope I explained well what I am trying to do here :)

Answer 1

Your collection method was a bit "broken".
This should work:
while ($row = $conn->fetch()) {
$id = $row['QuestionnaireId'];
if (!isset($data['questionnaires'][$id])) {
// First time we get this "QuestionnaireId" -
// define "container" that collects the related questions.
$data['questionnaires'][$id] = [
'id' => $row['QuestionnaireId'],
'title' => $row['QuestionnaireTitle'],
'questions' => [],
];
} else {
// Already got this "container" -
// put the question into the collection.
$data['questionnaires'][$id]['questions'][] = [
'id' => $row['QuestionId'],
'text' => $row['Question']
];
}
}