Laravel Eloquent group results by relation - laravel

Question

I am struggling to get Laravel Eloquent to retrieve and group results in the way that i'd like.
Basically I am creating a 'My Agenda' page which shows all task in order of their due date, but grouped together if 2 or more Tasks (in order) belong to the same Stage, and likewise if 2 or more stages belong to the same project.
My data is Projects -> (has many) Stages -> (has many) Tasks
I would like to output my data as follows:
Project B
Stage 2
Task 1 (due 1st Sep)
Task 3 (due 2nd Sep)
Stage 1
Task 2 (due 3rd Sep)
Project A
Stage 1
Task 2 (due 4th Sep)
Project B <---- repeated as Project A has a stage->task due before these tasks due
Stage 3
Task 2 (due 5th Sep)
Project A <---- repeated as Project B has a stage->task due before
Stage 1 <---- repeated
Task 1 (due 6th Sep)
Any ideas how I can achieve this? I am open to doing this on the front end with JS/Vue/Lodash.
Thanks in advance!
M

Answer 1

I think you can do it this way:
First, let's combine all the tables with JOIN. If you want to see all projects and stages that don't have any relational data, you can use LEFT JOIN, or maybe RIGHT JOIN, I don't know which one will work.
$tasks = Task::orderBy("due")
->join("stages", "stages.id", "=", task.stage_id)
->join("projects", "projects.id", "=", stages.project_id)
->select("pick the columns you want to have")
->get();
I think you should aim for this type of array as your output, so you won't have any issues because of the repeated key names.
/*
$output = [
[
'project'=> A,
'stages'=> [
stage_name => [task 1, task 2],
stage_name => [task 4, task 8],
],
],
[
'project'=> B,
'stages'=> [
stage_name => [task 5],
],
],
[...]
];
*/
To create that type of array, the function down below should work.
$output = [];
foreach($tasks => $task) {
$project = $task['project_name'];
$lastEntry = $output[count($output) - 1];
if ( count($output) > 0 && $lastEntry['project'] == $project) {
// this means $task should be inserted in the last array.
// You should check for stages.
if (array_key_exists($task['stage_name'], $lastEntry['stages'])) {
$lastEntry['stages'][$task['stage_name']][] = $task;
} else {
$lastEntry['stages'][$task['stage_name']] = [$task];
}
// I think $lastEntry['stages'][$task['stage_name']][] = $task; will work without checking stage names, but I can't be sure, you need to try it.
} else {
// This means you should create a new item in $output.
$output[] = [
'project' => name,
'stages' => [
'stage_name' => [$task];
]
]
}
}
I created those codes here directly. There can be typos and everything, but the logic should work.