Since you have an Eloquent Collection (a child class of the generic Collection class) you can use the getDictionary method. $collection->getDictionary() will give you an array of your Category objects keyed by their primary keys.

If you wanted another Collection rather than a native PHP array, you could instead use $collection->keyBy($property). It looks like your primary key is category_id, so $collection->keyBy('category_id'). You can use that method to key by any arbitrary property, including any get mutators you may have written.

While getDictionary is unique to the Eloquent Collection extension, keyBy is available to all Laravel Collection objects. See the Laravel 4.2 API docs or Laravel 5.0 API docs.

You have a Support\Collection/Database\Eloquent\Collection you can use the method lists('id') to return an array of the id of each of the models within the collection.

Then use array_combine to map the keys to the models. The result of which will be an array with the id mapped to their corresponding model.

If you need id as the key, then rely on the Collection:

$collection = Model::all();

$collection->getDictionary();

// returns:
array(
  1 => object(Model) ( ... ),
  2 => object(Model) ( ... ),
  ...
  idN => object(Model) ( ... )
);

Otherwise, nice or not, you can do this:

$keys = $collection->lists('columnName');

$arrayOfModels = array_combine($keys, $collection->getDictionary);

pluck('label','id') on the get() output is what you're looking for in Laravel 5.8+, which gives you a collection, ready to be toArray()ed

eg:

$options = \App\DataChoice::where([ 'field_id' => $dataField->id , 'active' => true ])->get()->pluck('label','id')->toArray();

I had a similar challenge - I wanted to a PHP array to allow me to create a with an for each choice, with the 's value being the id auto increment column, and the displayed text being the value.