[4.2][Proposal] Field callbacks - afterCreate(), afterUpdate, afterSave(), beforeCreate(), beforeUpdate(), beforeSave()

[tabacitu]

Here's a wild thought. Currently to add a field that uploads a file we need to:

• CrudController - add the upload field;
• Model - add a mutator;
• Model - add a deleting event on the model, so that the file is deleted when entry is;

But... what if we could include Step 2 in Step 1? What if we could add an Upload field like this:

$this->crud->addField([   // Upload
    'name' => 'image',
    'label' => 'Image',
    'type' => 'upload',
    'upload' => true,
    'disk' => 'uploads', // if you store files in the /public folder, please ommit this; if you store them in /storage or S3, please specify it;
    'path' => 'folder_1/folder_2',
    'after_save' => function($field, $entry, $value) {
        $entry->uploadFileToDisk($value, $field['attribute_name'], $field['disk'], $field['path']);
    }
    // optional:
    // 'temporary' => 10 // if using a service, such as S3, that requires you to make temporary URL's this will make a URL that is valid for the number of minutes specified
]);

It would then become 2-step:

• CrudController - add the upload field (and the callback to do the uploading);
• Model - add a deleting event on the model, so that the file is deleted when entry is;

But what would be even cooler - is if field types would have some default logic. For example, the Upload field could have the above logic the default, since that's what most users do anyway. You could then add the field the exact same way you did before, but just skip the mutator step. Of course, this needs us to convert fields into PHP Classes first.

Thoughts anyone? Worth it or not? Any other places where these callbacks could be useful? I can think of image, upload_multiple, but what other fields? What other use cases would this enable?

[tabacitu]

This is no longer required, starting v5 we can use Model Events for the same purpose 🎉
https://backpackforlaravel.com/docs/5.x/release-notes#use-model-events-inside-crudcontrollers