Laravel 检索董事会的所有父母

Question

I have a board that's called "Announcements" which is in a board called "Important Information" in which that is in "Headquarters". Here is a visual representation of it.

Headquarters (The main board with no parents) [id = 1, parent_id = null]

↳ Important Information (1st child board of "Headquarters") [id = 2, parent_id = 1]

↳ Announcements (1st child board of "Important Information") [id = 3, parent_id = 2]

My objective is to get all of the "Announcements" parent boards in a Laravel model.

I already constructed a function that gets one parent board.

public function parent()
{
    return $this->where('id', $this->parent_id)->first();
}

If you were to use this function for the "Announcements" board, it would return the results of the "Important Information" board because that is the parent of "Announcements".

So let's say I were to create a function called listAllParents()

public function listAllParents()
{
    // code here
}

This function would return the results of all parents associated with the specified board. So if I were to use this function on "Announcements" I would want all parents associated with it to be returned.

Here is a small code example:

$board = Board::where('name', 'Announcements')->first();
$getAllParents = $board->listAllParents()->get();

return $getAllParents;

And what should be returned is a list of "Announcements" parent boards, which would be: "Important Information" & "Headquarters". What code should go into the listAllParents() function to make this possible?

If you need a better explanation, please let me know. I will be more than happy to help.

Thank you so much for your help.

Answer 1

Given your current structure, your best option is to iterate through each Board in your hierarchy until you reach a Board where parent_id === null . For example:

public function listAllParents()
{
    $board = $this;
    $parents = [];

    while (! is_null($board->parent_id)) {
        $board = $board->parent();
        $parents[] = $board;
    }

    return $parents;
}

This however is highly inefficient since you're executing a query to find the node at each level of the hierarchy.

An alternative approach would be to use a Nested Tree data structure, and there are various packages available to implement this functionality in Laravel.