Laravel 在集合序列化中保留组密钥

Question

Laravel v.5.8:

I want to group each child relation budgets and json serialize it.

$monthbudgets = \App\BudgetMonth::where('month', $curmonth)->with("budgets")->get();
    foreach ($monthbudgets as $month) {
        $month->budgets = $month->budgets->groupBy("customer_id");
    }
dd($monthbudgets[8]);

which will return:

//laravel collection of "budgets"
...[
    1 => [
        0 => []
        1 => []
    ],
    5 => [
        0 => []
    ]
]...

but using dd($monthbudgets[8]->jsonSerialize()) , it will return:

//array of "budgets"
...[
    0 => []
    1 => []
    2 => []
]...

Looks like it flattens it and removes the keys (1, 5).

I'm also open to suggestions for minimizing the grouping loop. I tried

->with(["budgets" => function ($query) {
    $query->groupBy("customer_id");
}])->get();

which will result in

Syntax error or access violation: 1055 'budgets.id' isn't in GROUP BY (...)

Answer 1

Laravel's jsonSerialize will call toArray :

// Model.php
public function toArray()
{
    return array_merge($this->attributesToArray(), $this->relationsToArray());
}

which merges the attributes and then the relations which makes it overwrite the attribute you've set.

You can set the relation with setRelation

foreach ($monthbudgets as $month) {
    $month->setRelation('budgets', $month->budgets->groupBy("customer_id"));
}