Extend Relation Controller delete query

[ericp-mrel]

Hi,

Does anyone know if it is possible to override or extend the relation manager delete action? I have some records which are seeded as part of the system and should be read-only, but the user is able to add their own custom records which they should be able to delete. I use a is_system_managed column in the DB to denote which ones are editable or not editable.

I tried to use controller middleware, but it seems it runs after the relation controller runs this method onRelationManageDelete which seems strange to me.

Curious if anyone knows of a way to prevent users from deleting certain records via the relation manager widget. Or other solutions that could work?

Thanks!

[mjauvin]

What about using this to filter-out those records?

https://wintercms.com/docs/backend/relations#extend-filter-widgets

Then use this on the widget object:

$widget->bindEvent('list.extendQuery', function ($query) {
    ...
});

[mjauvin]

The RelationController also has this code:

            if ($sqlConditions = $this->getConfig('manage[conditions]')) {
                $widget->bindEvent('list.extendQueryBefore', function ($query) use ($sqlConditions) {
                    $query->whereRaw($sqlConditions);
                }); 
            }
            elseif ($scopeMethod = $this->getConfig('manage[scope]')) {
                $widget->bindEvent('list.extendQueryBefore', function ($query) use ($scopeMethod) {
                    $query->$scopeMethod($this->model);
                }); 
            }   

So you should be able to use the conditions or scope relation config settings to modify the query.

ref. https://wintercms.com/docs/backend/relations#configuring-relation

[ericp-mrel]

The problem with doing something like this, is I want those records to still show up in the list because users can add/remove them from the relation. I just don't want them to be able to delete the system managed ones, and I still want them to be able to delete the user created ones.

Basically, I want to populate common options by default and allow users to create their own custom ones, but only allow them to delete the options they've created.

Hope that makes sense.

[ericp-mrel]

I think I may have found a work-around which works for my use case. While it probably is pretty hacky, it at least works since the relationExtendManageWidget() controller method is run before the RelationController runs the onRelationManageDelete() method.

# BackendController.php

// ...

public function relationExtendManageWidget($widget, $field, $model)
{
    // Do not allow backend users to delete system managed Plan Amenities.
    if ($this->getAjaxHandler() === 'onRelationButtonDelete' && $field === 'foo') {
            $ids = Foo::query()
                ->where('is_system_managed', false)
                ->whereIn('id', post('checked'))
                ->lists('id');

            request()->request->set('checked', $ids);
    }
}

I just have a question because I'm curious. Is it normal / expected for the controller middleware to be run after the Relation controller has already deleted the records? To me this seems like a bug since the middleware should run first so you can filter or do whatever to the request before any ajax actions are actually performed such as deleting records.

[mjauvin]

Then I would use the backend.ajax.beforeRunHandler event. The handler should be onRelationButtonDelete I believe

ref. https://wintercms.com/docs/events/event/backend.ajax.beforeRunHandler

[mjauvin]

Can you show how you tried to use the middleware in this case?

[ericp-mrel]

Here's how I tried to use the middleware:

class TestController extends Controller
{
    public $implement = [
        'Backend\Behaviors\ListController',
        'Backend\Behaviors\FormController',
        'Backend\Behaviors\RelationController',
        'Backend\Behaviors\ImportExportController',
    ];

    /** @var string|array */
    public $listConfig = 'config_list.yaml';

    /** @var string|array */
    public $formConfig = 'config_form.yaml';

    /** @var string|array */
    public $relationConfig = 'config_relation.yaml';

    /** @var string|array */
    public $importExportConfig = 'config_import_export.yaml';

    public function __construct()
    {
        parent::__construct();

        $this->middleware(function (Request $request, Response $response) {
            trace_log('controller middleware');

            dd(get_class($request), $response);
        });
    }
}

I added some logging statements inside the RelationController and that middlware function

// RelationController.php

    /**
     * Delete an existing related model completely
     */
    public function onRelationManageDelete()
    {
        $this->beforeAjax();

        trace_log('onRelationManageDelete');

        /*
         * Multiple (has many, belongs to many)
         */
        if ($this->viewMode === 'multi') {
            if (($checkedIds = post('checked')) && is_array($checkedIds)) {
                foreach ($checkedIds as $relationId) {
                    if (!$obj = $this->relationModel->find($relationId)) {
                        continue;
                    }

                    trace_log('$obj->delete()');
                    // $obj->delete();
                }
            }
        }
        /*
         * Single (belongs to, has one)
         */
        elseif ($this->viewMode === 'single') {
            $relatedModel = $this->viewModel;
            if ($relatedModel->exists) {
                trace_log('$relatedModel->delete()');
                // $relatedModel->delete();
            }

            // Reinitialise the form with a blank model
            $this->initRelation($this->model);

            $this->viewWidget->setFormValues([]);
            $this->viewModel = $this->relationModel;
        }

        return $this->relationRefresh();
    }

and here's the log output

[2022-09-28 20:08:00] local.INFO: onRelationManageDelete  
[2022-09-28 20:08:00] local.INFO: $obj->delete()  
[2022-09-28 20:08:00] local.INFO: $obj->delete()  
[2022-09-28 20:08:00] local.INFO: $obj->delete()  
[2022-09-28 20:08:00] local.INFO: $obj->delete()  
[2022-09-28 20:08:00] local.INFO: $obj->delete()  
[2022-09-28 20:08:00] local.INFO: $obj->delete()  
[2022-09-28 20:08:00] local.INFO: $obj->delete()  
[2022-09-28 20:08:00] local.INFO: $obj->delete()  
[2022-09-28 20:08:00] local.INFO: controller middleware  

This shows the middleware being executed after the records have been deleted.

[mjauvin]

The documentation says this regarding middleware:

Controller middleware is executed after the request is processed by Winter CMS, but before the response is sent to the browser.

ref. https://wintercms.com/docs/backend/controllers-ajax#controller-middleware

[ericp-mrel]

This works for my needs: #719 (reply in thread)

Then I would use the backend.ajax.beforeRunHandler event. The handler should be onRelationButtonDelete I believe

ref. https://wintercms.com/docs/events/event/backend.ajax.beforeRunHandler

Thanks for the suggestion @mjauvin