Grammar::parameterize() must be of the type array
Stefan Izdrail
Founder & Senior Architect · 2026-06-29
Title: Understanding and Resolving the "Grammar::parameterize() must be of the type array" Error for Multiple Select Form Input in Laravel
Body:
You encountered an error while working with a multiple-value input select form in your Laravel application, displaying the message "Argument 1 passed to Illuminate\Database\Grammar::parameterize() must be of the type array, string given," when adding
array[] in your View. This issue is primarily caused due to a misconception that Laravel's $request->all(), which gives all input from the request, can be directly passed to Eloquent models to create or update multiple relations.
To address this error, you should follow these steps:
1. Remove array[] from your View's select form attribute. Your form should now look like this:
<div class = "form-group {{ $errors->has('approver') ? ' has-error' : '' }}">
<label for = "approver" class = "control-label">Approver:</label>
<select name = "approver" multiple class = "form-control select2-multi">
@foreach ($approver as $list)
<option value = "{{ $list->id }}">{{ $list->username }}</option>
@endforeach
</select>
@if ($errors->has('approver'))
<span class = "help-block">{{ $errors->first('approver') }}</span>
@endif
</div>{!! Form::close() !!}public function getDocuments()
{
$approver = DB::table('users')->where('id', '!=', Auth::id())->get();
return view ('document.create')->with('approver', $approver);
}
public function postDocuments(Request $request)
{
$this->validate($request,
[
'title' => 'required|regex:/(^[A-Za-z0-9 ]+$)+/|max:255',
'content' => 'required',
'category' => 'required',
'recipient' => 'required',
]);
$document = new Document();
$approve = new Approve();
$user = Auth::user();
//Request in the form
$document->title = $request->title;
$document->content = $request->content;
$document->category_id = $request->category;
foreach ($approve->all() as $item) {
$document->sentToApprovers()->sync([$item->id],false);
}
$document->save();
}
b. Implement a function that accepts the request data and returns multiple approvers' IDs as an array, ensuring proper Laravel relationship handling:
public function createApprovers($data)
{
$approverIds = [];
foreach ($data['approver'] as $listId) {
$approver = Approver::find($listId);
if (empty($approver)) {
throw new \Exception('Invalid approver');
}
array_push($approverIds, $approver->id);
}
return $approverIds;
}public function postDocuments(Request $request)
{
$this->validate($request,
[
'title' => 'required|regex:/(^[A-Za-z0-9 ]+$)+/|max:255',
'content' => 'required',
'category' => 'required',
'recipient' => 'required',
]);
$document = new Document();
$approve = new Approve();
$user = Auth::user();
//Request in the form
$document->title = $request->title;
$document->content = $request->content;
$document->category_id = $request->category;
$approverIds = $this->createApprovers($request->all());
foreach ($approve->all() as $item) {
$document->sentToApprovers()->sync([$item->id],false);
}
$document->save();
}