How to modify delete method using objectManager

Question

I have found the some extension from Amasty and here is the snipped code to delete the data using objectManager :

public function deleteBy($methodId)
{
    /**
     * @var \Amasty\ShippingTableRates\Model\ResourceModel\Rate $resource
     */
    $resource = $this->_objectManager->get('Amasty\ShippingTableRates\Model\ResourceModel\Rate');
    $resource->deleteBy($methodId);
}

I know that from using objectManager is not the recommended way from here and here.

The problem using objectManager when I try to change the behavior of import csv file on this class using Plugin it breaks the delete function, and every time admin try to delete always shows this error :

array_values() expects parameter 1 to be array, object given in /var/www/html/vendor/magento/framework/Interception/Interceptor.php on line 146

Here is my Plugin :

use Amasty\ShippingTableRates\Model\Rate as RateAmasty;


class Rate extends RateAmasty
{
    /**
     * Change total number column
     * We change the hidden column == 0 because additional column
     */
    const COL_NUMS = 20;
    const HIDDEN_COLUMNS = 0;

    /**
     * index for generated columns
     */
    const NUM_ZIP_FROM = 16;
    const NUM_ZIP_TO = 17;

    /**
     * import csv file
     */
    public function aroundImport(RateAmasty $subject, \Closure $proceed,$methodId, $fileName)
    {

        $err = [];

        $fp = $this->_file->fileOpen($fileName, 'r');
        $methodId = intval($methodId);
        if (!$methodId) {
            $err[] = __('Specify a valid method ID.');
            return $err;
        }

        $countryCodes = $this->_helper->getCountries();
        $countryNames = $this->_helper->getCountries(true);
        $typeLabels = $this->_helper->getTypes(true);

        $data = [];

        $currLineNum = 0;
        while (($line = $this->_file->fileGetCsv($fp, self::MAX_LINE_LENGTH, ',', '"')) !== false) {
            $currLineNum++;

            if ($currLineNum == 1) {
                continue;
            }

            if ((count($line) + self::HIDDEN_COLUMNS) != self::COL_NUMS) {
                $err[] = 'Line #' . $currLineNum . ': warning, expected number of columns is ' . self::COL_NUMS;
                if (count($line) > self::COL_NUMS) {
                    for ($i = 0; $i < count($line) - self::COL_NUMS; $i++) {
                        unset($line[self::COL_NUMS + $i]);
                    }
                }

                if (count($line) < self::COL_NUMS) {
                    for ($i = 0; $i < self::COL_NUMS - count($line); $i++) {
                        $line[count($line) + $i] = 0;
                    }
                }
            }

            $dataZipFrom = $this->_helper->getDataFromZip($line[self::ZIP_FROM]);
            $dataZipTo = $this->_helper->getDataFromZip($line[self::ZIP_TO]);
            $line[self::NUM_ZIP_FROM] = $dataZipFrom['district'];
            $line[self::NUM_ZIP_TO] = $dataZipTo['district'];

            for ($i = 0; $i < self::COL_NUMS - self::HIDDEN_COLUMNS; $i++) {
                $line[$i] = str_replace(["\r", "\n", "\t", "\\", '"', "'", "*"], '', $line[$i]);
            }

            $countries = [''];
            if ($line[self::COUNTRY]) {
                $countries = explode(',', $line[self::COUNTRY]);
            } else {
                $line[self::COUNTRY] = '0';
            }

            $line = $this->_setDefaultLineValues($line);

            $typesData = $this->_prepareLineTypes($line, $err, $currLineNum, $typeLabels);
            $line = $typesData['line'];

            foreach ($countries as $country) {
                if ($country == 'All') {
                    $country = 0;
                }

                if ($country && empty($countryCodes[$country])) {
                    if (in_array($country, $countryNames)) {
                        $countryCodes[$country] = array_search($country, $countryNames);
                    } else {
                        $err[] = 'Line #' . $currLineNum . ': invalid country code ' . $country;
                        continue;
                    }

                }
                $line[self::COUNTRY] = $country ? $countryCodes[$country] : '0';

                $statesData = $this->_prepareLineStates($line, $err, $currLineNum, $country, $methodId);
            }// countries
        } // end while read
        fclose($fp);

        if (isset($statesData['data_index'])) {
            $err = $this->returnErrors($statesData['data'], $methodId, $currLineNum, $statesData['err']);
        }

        return $err;

    }

}

My question is how to modify this delete method to the best way in magento 2 ? Since I'm still new to this big platform and still don't know how.

Answer 1

If you don't want to you ObjectManagerwhich is not recommended way to do that. There are several options you can choose :

1. Amasty\ShippingTableRates\Model\Rate create a constructor in you class and make it accessible using your local variable like protected _rate;
2. Find the interface class in the Api Folder in the module directory usually it will have name like RateInterface. and create your constructor in your class and place additional argument just like in the step 1.
3. If you don't find Interface class then you can pass directly call the Amasty\ShippingTableRates\Model\Rate to your constructor class.

Hopefully this will helps others