Sorting Laravel collection by 2 parameters - php

Question

It's fun with sorting today! Sigh. I have a big collection of eloquent models that need to be grouped together in the array by one parameter, and ordered in those 'clumps' based on another parameter. This might be hard to explain :(
$master is a collection of Eloquent results, I'm not sure how to write them out here, looping over this I can access all the models functions / relationships
$master = [];
These have 2 properties that need to be the basis for a sort, example of the properties below
//Object 1
$master->carry = 0;
$master->section = 'red';
//Object 2
$master->carry = 1;
$master->section = 'blue';
//Object 3
$master->carry = 0;
$master->section = 'blue';
I want to sort a massive collection of these so that each $master->section is in one 'clump' in the array and inside that 'clump' the $master->carry=0 products are listed last.
From the example above I'd expect Object1, Object3, Object2
I've tried a few different $master->sort() and $master->sortBy() things, but each new sort throws off the old sort :(
I've got the code below currently, which groups up all the colors, but it doesn't order them based on $master->carry yet
$order = array('red', 'blue', 'green');
$master = $master->sort(function ($a, $b) use ($order) {
$pos_a = array_search($a->sectionheader, $order);
$pos_b = array_search($b->sectionheader, $order);
return $pos_a - $pos_b;
});

Answer 1

As I understood, you want to sort your collection the following way:
sort by section in the order stored in $order array
within section move the elements with carry = 0 to the end
You need to pass a function that would implement such logic to $master collection. This function should take 2 arguments (2 elements of collection), compare them and return:
0 if elements are equal
1 if the first element is greater than the second element
-1 if the first element is smaller than the second element
In your case the following callback should work:
$master = $master->sort(function ($a, $b) use ($order) {
// get order of first element's section
$pos_a = array_search($a->section, $order);
// get order of second element's section
$pos_b = array_search($b->section, $order)
// if sections are different the value of carry doesn't matter
// as element's sections are enough to determine which of them is larger
if ($pos_a != $pos_b) {
return $pos_a - $pos_b;
}
// carry values are equal, so consider elements equal
if ($a->carry == $b->carry) {
return 0;
}
if (!$a->carry) {
// if $a->carry is equal to 0 it should be put at the end, so after $b
return 1;
}
if (!$b->carry) {
// if $b->carry is equal to 0 it should be put at the end, so after $a
return -1;
}
// otherwise elements can be considered equal
return 0;
});