Set Coupen for specific Products. Magento 2

Question

I create the coupon function in Helper which is

public function setCoupon()
    {
        // $this->_state->setAreaCode('adminhtml');  
        // $this->_state->setAreaCode('frontend');  




   $coupon['name'] = 'Offer';
    $coupon['desc'] = 'Discount for vip signup coupon.';
    $coupon['start'] = date('Y-m-d');
    $coupon['end'] = '';
    $coupon['max_redemptions'] = 1;
    $coupon['discount_type'] ='by_fixed';
    $coupon['discount_amount'] = 15;
    $coupon['flag_is_free_shipping'] = 'no';
    $coupon['redemptions'] = 1;
    $coupon['code'] ='NL02-1234'; //this code will normally be autogenetated but i am hard coding for testing purposes  

    $this->_rule->setName($coupon['name'])
            ->setDescription($coupon['desc'])
            ->setFromDate($coupon['start'])
            ->setToDate($coupon['end'])
            ->setUsesPerCustomer($coupon['max_redemptions'])
            ->setCustomerGroupIds(array('0','1','2','3',))
            ->setIsActive(1)
            ->setSimpleAction($coupon['discount_type'])
            ->setDiscountAmount($coupon['discount_amount'])
            ->setDiscountQty(1)
            ->setApplyToShipping($coupon['flag_is_free_shipping'])
            ->setTimesUsed($coupon['redemptions'])
            ->setWebsiteIds(array('1'))
            ->setCouponType(2)
            // ->setProductIds(array(1,2,3));
            // ->setProductIds(array('1','2','3'))
            ->setProductIds(1)
            ->setCouponCode($coupon['code'])
            ->setUsesPerCoupon(NULL);
    $this->_rule->save();
}

where $this->_rule is object of Magento\SalesRule\Model\Rule class it works perfectly but you guys can see that I tried setProductIds to set it for specific products but when it was in array it show me an error Array to String and when I tried setProductIds only for one product Id then it not gives me any error but the coupon works on the every product. How can I set this???

Answer 1

use Magento\SalesRule\Model\Data\Rule class and function setProductIds() which will accept param type array but function setProductIds() inside Magento\SalesRule\Model\Rule accecpt only string not array. please check core files for more information.