Laravel选择具有默认值的框

Question

I have a category/subcategory setup on my application in a way that each category can have parent_id which is 0 if we have main category, or is number pointing to a main category if it is a subcategory.

Everything works fine except the edit method where I'd like a select box to have "Main Category" on top of the list able to select.

public function edit(Category $category)
{
    $parent_categories = Category::where('parent_id', 0)->pluck('name', 'id')->prepend('Main Category', '');
    return view('category.edit', compact('category', 'parent_categories'));
}

If I prepend it like this it works, but then in view when I edit a category that value is always selected even though category points to another parent_id . When I don't have prepend() then it selects value fine. This is view

{!! Form::select('parent_id', $parent_categories, null, ['class' => 'form-control'] ) !!}

EDIT:

actually it doesn't select it fine in either case

Answer 1

just replace $selctedValue as the value to be selected in the below code .
{!! Form::select('parent_id', $parent_categories, $selctedValue, ['class' => 'form-control'] ) !!}