Various errors trying to add an extra function to CRUD - laravel

Question

First, I clearly do not fully understand routing. This problem is not DB related, but management of images in a folder but I used the Resource process to create the crud elements. Maybe this is not the correct approach for file management.
I have the following view (it is not a finished view, just for testing):
#extends('layouts.app')
#section('content')
<!--/*{ { dd(get_defined_vars(), url()->current()) } }*/-->
#if(!Auth::guest())
#if(Auth::user()->admin == 1)
<h3>Manage Gallery</h3>
#else
<h3>Gallery </h3>
#endif
#else
<h3>Gallery (Visitor)</h3>
#endif
<style>
.flex-container {
display: -webkit-flex;
display: flex;
-webkit-flex-direction: row;
flex-direction: row;
-webkit-align-items: center;
align-items: center;
justify-content: space-around;
flex-wrap: wrap;
min-width: 100px;
max-width: 1100px;
}
.flex-item {
display:flex;
align-items: center;
/*height: 100px;
width: 200px;*/
background-color: #f5f8fa;
color: white;
justify-content: space-between;
margin: 3px;
padding: 10px 0 0 10px;
}
.flex-item img{
flex-grow:0;
flex-shrink:0;
}
span {
padding-left: 5px;
}
</style>
#if(count($data['folders'])>0)
<div class="flex-container">
#foreach ($data['folders'] as $folder)
<div class="flex-item">
<form action="{{action('GalleryController#show', $folder)}}" method="get">
<input name="_method" type="hidden" value="show">
<button class="btn btn-lg px-5 btn-primary" style="margin:5px" type="submit" role="button" <img src="assets/folder_image.png" height="30">{{$folder}}</button>
</form>
<!-- --------------------------------------- -->
<!-- Only show crud buttons if administrator -->
<!-- --------------------------------------- -->
#if(!Auth::guest())
#if(Auth::user()->admin == 1)
Delete 1 Picture
<form action="{{action('GalleryController#destroy', $folder)}}" method="post">
{{csrf_field()}}
<input name="_method" type="hidden" value="DELETE">
<button class="btn btn-danger btn-sm" type="submit">Delete entire Folder</button>
</form>
Add piccies
<form action="{{action('GalleryController#add')}}" method="post">
{{csrf_field()}}
<input name="folder" type="hidden" value='{{$folder}}'>
<button class="btn btn-info btn-sm" style="margin:5px" type="submit">Add new pictures</button>
</form>
#endif
#endif
</div>
#endforeach
#if(!Auth::guest())
#if(Auth::user()->admin == 1)
<div class="flex-item" style="width:1500px"> <!-- large width forces flexbox to new row -->
Create
</div>
#endif
#endif
</div>
#else
#if(!Auth::guest())
#if(Auth::user()->admin == 1)
<br><br><br>
Create
#endif
#endif
<p>No Gallery Folders available.</p>
#endif
#endsection
I cannot recall WHY I use a link for 'delete 1 picture' and a form for 'delete entire folder'. I assume I found it in some tutorial and just used it. I want to either delete a specific image (this works fine using the 'edit' component of the Controller) or delete the entire folder (this also works fine using the 'destroy' component of the Controller).
So the next step is to be able to add new folders, or images to a specific folder. Adding a new folder works fine as well using the 'create' component of the Controller.
Then it falls apart trying to add a new image. With the code as shown, I get 2 different errors depending upon whether I click the 'Add Piccies' button or the 'Add new pictures' button.
My route is (and I have tried both get and post):
Route::post('/gallery/add/', 'GalleryController#add');
/* Dynamically create all routes for CRUD for gallery table */
Route::resource('gallery', 'GalleryController');
If I use the 'add piccies' button I get a URL of 'http://hdkumdo.com/lsapp/public/gallery/add?2019_Masters' where ?2019 etc is the folder concerned.
If I use the 'add new picture' button I get the error "Type error: Too few arguments to function App\Http\Controllers\GalleryController::add(), 0 passed and exactly 1 expected'.
If I change the route from post to get, I get the error ' Symfony \ Component \ HttpKernel \ Exception \ MethodNotAllowedHttpException
No message'.
The rendered view looks like this:
View of buttons
Because I have used the basic CRUD elements created by RESOURCE, I added a new function to the controller thinking I can just call it. The code fragment is:
/**
* Show the form for uploading pictures.
*
* #return \Illuminate\Http\Response
*/
public function add($gallery)
{
$folder = $gallery;
$title = 'Add Pictures';
TheUser::get_Role();
$userRole = session('userRole');
Log::info('GalleryController.add called : user Role =>' . $userRole . ' Folder:' . $folder );
$data = array(
'userRole' => $userRole,
);
/*dd($data);*/
return view('gallery.add')->with('title', $title)->with('data', $data);
}
So, any suggestions/advice etc would be most welcome.

Answer 1

See the comments above. It is something to be aware of as it took me several days of head scratching and required a little lateral thinking.