Assign Related Product In Magento 2 API - php

Question

I am using magento 2 api for assigning product link like related or crosssell
using api /V1/products/{sku}/links
Here is My Sample Code
<?php
error_reporting(E_ALL);
define('mag_apiurl',"http://www.mywebsite.com/rest/V1/");
define('tn_webshopKey',"myshowpkey");
$sku1 = "sku1";
$sku2 = "sku2";
$productData = array(
"items" => array(
"sku" => $sku1,
"linkType" => 'related',
"linkedProductSku" => $sku2,
"linkedProductType" => "simple",
"position" => 0
)
);
$headers = array("Content-Type:application/json","Authorization: Bearer ".tn_webshopKey);
$requestUrl= mag_apiurl.'products/'.$sku1.'/links';
$ch = curl_init($requestUrl);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($productData));
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
echo $returnProductDetails = curl_exec($ch);
?>
But Every time i run the script its
response
{"message":"%fieldName is required filed.","parameters":{"fieldName":"linkType"}}
But the link type 'related' is already defined in my data (productData)
Does anyone knows the solution or related link which helps :)

Answer 1

Could you try setting "linkType" to 1 instead of "related"
$linkTypes = ['related' => 1, 'upsell' => 4, 'crosssell' => 5, 'associated' => 3];

Answer 2

Sorry Its my fault i'am reading the swagger api documentation for enterprise version of magento-2.2.* but i am working on magento-2.1.*
Actual Code Should be
$productData = array(
"items" => array(
array(
"sku" => $sku1,
"link_type" => 'related',
"linked_product_sku" => $sku2,
"linked_product_type" => "simple",
"position" => 0
)
)
);
/*
THE JOSN FORMAT START
{
"items": [
{
"sku": "string",
"link_type": "string",
"linked_product_sku": "string",
"linked_product_type": "string",
"position": 0,
"extension_attributes": {
"qty": 0
}
}
]
}
***************END************/
There are some differences ive noticed between those documentation that each document have different model schema declaration like some has snake_case and on other hand some has camelCase so do not begin confused between the documentation of swagger and select appropriate version of document for each store