curl --request POST \
  --url https://platform-staging.get-rial.com/v1/link-templates/{slug}/import/preview \
  --header 'Content-Type: application/json' \
  --cookie rial_session= \
  --data '
{
  "csv": "external_ref\nci-inso-row-1\nci-inso-row-2\n"
}
'

import requests

url = "https://platform-staging.get-rial.com/v1/link-templates/{slug}/import/preview"

payload = { "csv": "external_ref
ci-inso-row-1
ci-inso-row-2
" }
headers = {
    "cookie": "rial_session=",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {cookie: 'rial_session=', 'Content-Type': 'application/json'},
  body: JSON.stringify({csv: 'external_ref\nci-inso-row-1\nci-inso-row-2\n'})
};

fetch('https://platform-staging.get-rial.com/v1/link-templates/{slug}/import/preview', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://platform-staging.get-rial.com/v1/link-templates/{slug}/import/preview",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'csv' => 'external_ref
ci-inso-row-1
ci-inso-row-2
'
  ]),
  CURLOPT_COOKIE => "rial_session=",
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://platform-staging.get-rial.com/v1/link-templates/{slug}/import/preview"

	payload := strings.NewReader("{\n  \"csv\": \"external_ref\\nci-inso-row-1\\nci-inso-row-2\\n\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("cookie", "rial_session=")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://platform-staging.get-rial.com/v1/link-templates/{slug}/import/preview")
  .header("cookie", "rial_session=")
  .header("Content-Type", "application/json")
  .body("{\n  \"csv\": \"external_ref\\nci-inso-row-1\\nci-inso-row-2\\n\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://platform-staging.get-rial.com/v1/link-templates/{slug}/import/preview")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["cookie"] = 'rial_session='
request["Content-Type"] = 'application/json'
request.body = "{\n  \"csv\": \"external_ref\\nci-inso-row-1\\nci-inso-row-2\\n\"\n}"

response = http.request(request)
puts response.read_body

{
  "column_mapping": {
    "external_ref": "external_ref"
  },
  "ignored_columns": [],
  "total_rows": 2,
  "valid_rows": 2,
  "invalid_rows": [],
  "invalid_rows_total": 0,
  "would_abort": false,
  "preview": [
    {
      "row": 2,
      "subject": {
        "person": {
          "external_ref": "ci-row-1"
        }
      }
    }
  ]
}

{
  "error": {
    "code": "<string>",
    "message": "<string>",
    "fields": [
      {
        "path": "<string>",
        "message": "<string>"
      }
    ]
  }
}

{
  "error": {
    "code": "not_found",
    "message": "Resource not found"
  }
}

{
  "error": "<string>"
}

{
  "error": "storage_unavailable"
}