选项值默认值

I have this bit in my view,

<div class="form-group">
  <label for="theme" class="col-sm-3 control-label">Theme</label>
    <select class="form-control" id="theme" name="theme">
      <option value="0">Default Theme</option>
      <option value="1">Dark Theme</option>
    </select>
</div>

and in my controller

/**
 * Change User Account Settings
 *
 * @access public
 * @return view user.settings
 */
public function changeSettings($username, $id)
{
    $user = Auth::user();
    if (Request::isMethod('post')) {
        $user->style = (int) Request::get('theme');
        $user->save();
    return Redirect::route('profil', ['username' => $user->username, 'id' => $user->id])->with(Toastr::success('Your Account Was Updated Successfully!', 'Yay!', ['options']));
    } else {
        return redirect()->back()->with(Toastr::warning('Something Went Wrong!', 'Error', ['options']));
    }
}

how can I make it so the option selected value defaults to what style the user has selected in the DB?

In your view, you make it like so:

<option value="0" @if($selectedTheme == 0) SELECTED @endif>Default Theme</option>
<option value="1" @if($selectedTheme == 1) SELECTED @endif>Some other theme Theme</option>

(Of course, change $selectedTheme to whatever is returned by your controller.)