Answers for "error deleted at is null laravel"

laravel on delete set null

$table->...->onDelete('set null');

#First make sure you set the foreign key field as nullable:
$table->integer('foreign_id')->unsigned()->nullable();

get deleted value laravel

You can get also soft deleted record using withTrashed() of Laravel 
Eloquent. It will return all record from table.

Item::withTrashed()->get();

You can get only soft deleted row using onlyTrashed() of Laravel Eloquent.

Item::onlyTrashed()->get();