Marco Marco - 1 month ago 10
MySQL Question

Laravel - sorting an array of collections by the property of their relationship object

I have two tables

magazines
with a field
product_code
, and another table
issues
. They have
belongsToMany
relationship.

Magazine model:

public function issues()
{
return $this->hasMany('App\Issue');
}


Issue model:

public function magazine()
{
return $this->belongsTo('App\Magazine');
}


Currently I have a query where I get collections of issues grouped by magazine id and ordered by the date of the last issue.

$issues = Issue::orderBy('date', 'desc')->get()->groupBy('magazine_id');


This is how the result of my query looks like:

Collection {#431 ▼
#items: array:23 [▼
103 => Collection {#206 ▼
#items: array:52 [▶]
}
106 => Collection {#216 ▶}
124 => Collection {#452 ▶}
112 => Collection {#451 ▶}
115 => Collection {#450 ▶}
123 => Collection {#449 ▶}
107 => Collection {#448 ▶}
113 => Collection {#447 ▶}
117 => Collection {#446 ▶}
109 => Collection {#445 ▶}
110 => Collection {#444 ▶}
121 => Collection {#443 ▶}
120 => Collection {#442 ▶}
114 => Collection {#441 ▶}
116 => Collection {#440 ▶}
118 => Collection {#439 ▶}
126 => Collection {#438 ▶}
125 => Collection {#437 ▶}
119 => Collection {#436 ▶}
122 => Collection {#435 ▶}
105 => Collection {#434 ▶}
111 => Collection {#433 ▶}
104 => Collection {#432 ▶}
]
}


So, since I have 24 magazines, there are 24 collections of
issues
in the array, and each
collection
of
issues
belongs to one
magazine
. The collections are sorted by the date of the latests issue of each collection and issues inside of each collection are ordered by date as well. So, first collection in the array will be the one which has the latest issue in the table
issues
, the second collection will be the one which has the second latest issue in the same table and so on.

Since I will get an array of users subscriptions, which will consist of
product codes
like this:

$productCodes = ['aa1', 'bb2', 'cc3'];


I need to expand this query and sort the collections further by the
$productCodes
array that I will get. I need to check the codes from the
productCodes
array in the table
magazines
where I have the
product_code
field. The collections of issues grouped by
magazine
, should be then sorted so that the first collections are the ones whose
magazine
that they belong to has the same
product_code
as the code in the array
productCodes
, and amongst them, the first one would be whose collection has the latest issue by date. Then the rest of the collections should just be sorted by date. How can I make this kind of query?

Update

I have tried with a suggested code from @Paul Spiegel in the answers, and now I get an array of collections, with the collections of magazine issues. Issues in each magazine collection are ordered by date, and magazine collections that have the same
product_code
as in the
$productCodes
array are at the beginning of the array, but the the array of magazine collections is still not sorted by the date of the latest issue from each of the magazine collections.

Answer

First of all: Instead of using Collection::groupBy() you can just use relations:

$magazines = Magazine::with(['issues' => function($query) {
    $query->orderBy('date', 'desc');
}]);

This will give you a collection of Magazines including related issues in an array. The issues array is sorted by date desc.

Now you can split the result using two queries with different conditions:

$baseQuery = Magazine::with(['issues' => function($query) {
    $query->orderBy('date', 'desc');
}]);

$query1 = clone $baseQuery;
$query2 = clone $baseQuery;

$query1->whereIn('product_code', $productCodes);
$query2->whereNotIn('product_code', $productCodes);

$query1 will return all magazines with product_code from the array. $query2 will return all the other magazines.

You have now two ways to combine the two results:

1) Use Eloquent::unionAll()

$unionQuery = $query1->unionAll($query2);
$magazines = $unionQuery->get();

2) Use Collection::merge()

$magazines1 = $query1->get();
$magazines2 = $query2->get();
$magazines = $magazines1->merge($magazines2);

In both cases you will get the same result: A collection of magazines. The magazines with product_code from the $productCodes array are sorted first. Every Magazine object contains an array issues with related Issue objects.

If you want to get rid of the Magazine objects and really need the result to look like in your question, you can still do:

$issues = $magazines->keyBy('id')->pluck('issue');

But there is probably no need for that.

Update

If you really need the two parts of the Magazine collection to be sorted by the latest Issue.. I don't see any way without using a JOIN or sorting in PHP with a closure. Sorting magazines with a join would also need an aggregation. So i would switch back to your original query extending it with a join and split it in two parts as showed above:

$baseQuery = Issue::join('magazines', 'magazines.id', '=', 'issues.magazine_id');
$baseQuery->orderBy('issues.date', 'desc');
$baseQuery->select('issues.*');

$query1 = clone $baseQuery;
$query2 = clone $baseQuery;

$query1->whereIn('magazines.product_code', $productCodes);
$query2->whereNotIn('magazines.product_code', $productCodes);

And then

$issues1 = $query1->get()->groupBy('magazine_id');
$issues2 = $query2->get()->groupBy('magazine_id');

$issues = $issues1->union($issues2);

or

$issues = $query1->unionAll($query2)->get()->groupBy('optionGroupId');