Transform Collections into Key-Value Maps with mapWithKeys()

Use mapWithKeys() to transform collections into associative dictionaries with custom keys and values in a single operation.

When converting an Eloquent collection or dataset into a keyed associative array for dropdowns, chart data, or JSON dictionaries, combining keyBy() and map() loops over the collection multiple times.

mapWithKeys() allows you to define both the new key and new value simultaneously.

Basic Key-Value Mapping

use App\Models\User;

$users = User::all();

$lookup = $users->mapWithKeys(function (User $user) {
    return [$user->email => $user->name];
});

// Output:
// [
//     '[email protected]' => 'Punyapal Shah',
//     '[email protected]'     => 'Punyapal Shah',
// ]

Formatting Option Lists for Form Selects

$options = User::all()->mapWithKeys(function (User $user) {
    $label = "{$user->name} ({$user->department})";
    return [$user->id => $label];
});

Multiple Key-Value Pairs from Single Items

A single item can return multiple key-value pairs if needed:

$rates = collect($plans)->mapWithKeys(function ($plan) {
    return [
        $plan['id'] . '_monthly' => $plan['monthly_price'],
        $plan['id'] . '_annual'  => $plan['annual_price'],
    ];
});

Summary

• Transforms items into key-value pairs in a single collection pass.
• Closure must return an associative array with [key => value].
• Ideal for building select dropdown options and API lookup dictionaries.