Magento 2 REST api for PayPal module

I am creating an eCommerce application using Magento 2 REST api as backend and Angular 6 in front-end technology.

I have successfully integrated add/update/delete/list api of CART

I am using Paypal for payment methods, after getting a success response from PayPal, I need to store PayPal response to Magento 2 database but it is returning an error.

I need the parameter name of post request.

ERROR

"message": "No such entity with %fieldName = %fieldValue","parameters": {"fieldName": "cartId","fieldValue": null}

POST URL

http://127.0.0.1/magento2/index.php/rest/V1/carts/mine/payment-information

REQUEST DATA

    {"email": "vikram.sharma@xymob.in","cartId": 2,"billing_address": {"email": "vikram.sharma@xymob.in","region": "New York","region_id": 43,"region_code": "NY","country_id": "US","street": ["123 Oak Ave"],"postcode": "10577","city": "Purchase","telephone": "512-555-1111","firstname": "Jane","lastname": "Doe"         },"paymentMethod": {"method": "paypal_express","additional_data": {"paypal_express_payment_payload": "{\"id\":\"PAY-3F734824YB370341TLOQNO3Y\",\"intent\":\"sale\",\"state\":\"approved\",\"cart\":\"9W5899822J563802S\",\"create_time\":\"2018-09-18T10:50:31Z\",\"payer\":{\"payment_method\":\"paypal\",\"status\":\"VERIFIED\",\"payer_info\":{\"email\":\"vikramdummy-buyer@outlook.com\",\"first_name\":\"test\",\"middle_name\":\"test\",\"last_name\":\"buyer\",\"payer_id\":\"CAQR5B2LGGB9S\",\"country_code\":\"US\",\"shipping_address\":{\"recipient_name\":\"test buyer\",\"line1\":\"1 Main St\",\"city\":\"San Jose\",\"state\":\"CA\",\"postal_code\":\"95131\",\"country_code\":\"US\"}}},\"transactions\":[{\"amount\":{\"total\":\"102.00\",\"currency\":\"USD\",\"details\":{}},\"item_list\":{\"items\":[{\"name\":\"SATA HardDisk\",\"price\":\"1.00\",\"currency\":\"USD\",\"quantity\":2},{\"name\":\"Logitech Mouse\",\"price\":\"100.00\",\"currency\":\"USD\",\"quantity\":1}]},\"related_resources\":[{\"sale\":{\"id\":\"7CM65242K9229980W\",\"state\":\"completed\",\"payment_mode\":\"INSTANT_TRANSFER\",\"protection_eligibility\":\"ELIGIBLE\",\"parent_payment\":\"PAY-3F734824YB370341TLOQNO3Y\",\"create_time\":\"2018-09-18T10:50:29Z\",\"update_time\":\"2018-09-18T10:50:29Z\",\"amount\":{\"total\":\"102.00\",\"currency\":\"USD\",\"details\":{\"subtotal\":\"102.00\"}}}}]}]}","paypal_express_checkout_token": "EC-9W5899822J563802S","paypal_express_checkout_redirect_required": false,"paypal_express_checkout_payer_id": "CAQR5B2LGGB9S"        }    }}

Here is my Reference Url

Rest api for order place , Magento swagger

Here is my PHP curl code of postman:-

<?php$curl = curl_init();curl_setopt_array($curl, array(  CURLOPT_URL => "http://127.0.0.1/magento2/index.php/rest/V1/carts/mine/payment-information",  CURLOPT_RETURNTRANSFER => true,  CURLOPT_ENCODING => "",  CURLOPT_MAXREDIRS => 10,  CURLOPT_TIMEOUT => 30,  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,  CURLOPT_CUSTOMREQUEST => "POST",  CURLOPT_POSTFIELDS => "{\n  \"email\": \"vikram.sharma@xymob.in\",\n  \"billing_address\": {\n              \"email\": \"vikram.sharma@xymob.in\",\n              \"region\": \"New York\",\n              \"region_id\": 43,\n              \"region_code\": \"NY\",\n              \"country_id\": \"US\",\n              \"street\": [\"123 Oak Ave\"],\n              \"postcode\": \"10577\",\n              \"city\": \"Purchase\",\n              \"telephone\": \"512-555-1111\",\n              \"firstname\": \"Jane\",\n              \"lastname\": \"Doe\"\n     },\n    \"paymentMethod\": {\n    \"method\": \"paypal_express\",\n    \"additional_data\": {\n      \"paypal_express_payment_payload\": \"{\\\"id\\\":\\\"PAY-3F734824YB370341TLOQNO3Y\\\",\\\"intent\\\":\\\"sale\\\",\\\"state\\\":\\\"approved\\\",\\\"cart\\\":\\\"9W5899822J563802S\\\",\\\"create_time\\\":\\\"2018-09-18T10:50:31Z\\\",\\\"payer\\\":{\\\"payment_method\\\":\\\"paypal\\\",\\\"status\\\":\\\"VERIFIED\\\",\\\"payer_info\\\":{\\\"email\\\":\\\"vikramdummy-buyer@outlook.com\\\",\\\"first_name\\\":\\\"test\\\",\\\"middle_name\\\":\\\"test\\\",\\\"last_name\\\":\\\"buyer\\\",\\\"payer_id\\\":\\\"CAQR5B2LGGB9S\\\",\\\"country_code\\\":\\\"US\\\",\\\"shipping_address\\\":{\\\"recipient_name\\\":\\\"test buyer\\\",\\\"line1\\\":\\\"1 Main St\\\",\\\"city\\\":\\\"San Jose\\\",\\\"state\\\":\\\"CA\\\",\\\"postal_code\\\":\\\"95131\\\",\\\"country_code\\\":\\\"US\\\"}}},\\\"transactions\\\":[{\\\"amount\\\":{\\\"total\\\":\\\"102.00\\\",\\\"currency\\\":\\\"USD\\\",\\\"details\\\":{}},\\\"item_list\\\":{\\\"items\\\":[{\\\"name\\\":\\\"SATA HardDisk\\\",\\\"price\\\":\\\"1.00\\\",\\\"currency\\\":\\\"USD\\\",\\\"quantity\\\":2},{\\\"name\\\":\\\"Logitech Mouse\\\",\\\"price\\\":\\\"100.00\\\",\\\"currency\\\":\\\"USD\\\",\\\"quantity\\\":1}]},\\\"related_resources\\\":[{\\\"sale\\\":{\\\"id\\\":\\\"7CM65242K9229980W\\\",\\\"state\\\":\\\"completed\\\",\\\"payment_mode\\\":\\\"INSTANT_TRANSFER\\\",\\\"protection_eligibility\\\":\\\"ELIGIBLE\\\",\\\"parent_payment\\\":\\\"PAY-3F734824YB370341TLOQNO3Y\\\",\\\"create_time\\\":\\\"2018-09-18T10:50:29Z\\\",\\\"update_time\\\":\\\"2018-09-18T10:50:29Z\\\",\\\"amount\\\":{\\\"total\\\":\\\"102.00\\\",\\\"currency\\\":\\\"USD\\\",\\\"details\\\":{\\\"subtotal\\\":\\\"102.00\\\"}}}}]}]}\",\n      \"paypal_express_checkout_token\": \"EC-9W5899822J563802S\",\n      \"paypal_express_checkout_redirect_required\": false,\n      \"paypal_express_checkout_payer_id\": \"CAQR5B2LGGB9S\"\n    }\n  }\n}",  CURLOPT_HTTPHEADER => array("authorization: Bearer 1fpiepedxeqm6fse81icfv8yx4hmwbi3","cache-control: no-cache","content-type: application/json","postman-token: 85951c6b-ff29-b785-65c9-d10c39a34424"  ),));$response = curl_exec($curl);$err = curl_error($curl);curl_close($curl);if ($err) {  echo "cURL Error #:" . $err;} else {  echo $response;}