RuleRequest.php

    public function rules()
    {
        switch ($this->method()) {
            case 'POST':
                $rules = [
                    'name' => ['required'],
                    'email' => ['required', 'email', 'min:4', 'max:100', Rule::unique('admins')],
                    'password' => ['required', 'string', 'min:6', 'max:100'],
                    'password_confirmation' => ['required', 'string', 'min:6', 'max:100', 'same:password'],
                    'image' => ['image'],
                ];
                break;
            case 'PUT':
            case 'PATCH':
                $rules = [
                    'name' => ['required', Rule::unique('admins')->ignore($this->administrator)],
                    'email' => ['required', 'email', 'min:6', 'max:100', Rule::unique('admins')->ignore($this->administrator)],
                    'password' => ['string', 'min:6', 'max:100'],
                    'password_confirmation' => ['string', 'min:6', 'max:100', 'same:password'],                    
                    'image' => ['image'],
                ];
                break;
            default:
                return [];
                break;
        }

        if (request()->file('file') || request()->file('image')) {
            $rules = array_merge(
                $rules,
                ['image' => 'image|mimes:jpeg,jpg,png,gif']
            );
        }

        return $rules;
    }