如何卷曲json postfields？

Here's my code:

$pp = curl_init();
curl_setopt($pp, CURLOPT_URL, "https://api.paypal.com/v1/payments/billing-plans");
curl_setopt($pp, CURLOPT_HEADER, false);
curl_setopt($pp, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($pp, CURLOPT_SSLVERSION , 6);
curl_setopt($pp, CURLOPT_POST, true);
curl_setopt($pp, CURLOPT_RETURNTRANSFER, true); 
curl_setopt($pp, CURLOPT_POSTFIELDS, "page_size=3&status=ALL&page=1&total_required=yes");
curl_setopt($pp, CURLOPT_HTTPHEADER, array(
    "Content-Type: application/json",
    "Authorization: Bearer $token"
));

$result_pp = curl_exec($pp);
echo $result_pp;

Here's the error I'm getting:

{"name":"MALFORMED_REQUEST","message":"The request JSON is not well formed.","information_link":"https://developer.paypal.com/webapps/developer/docs/api/#MALFORMED_REQUEST","debug_id":"b742c35fe6e0e"}

This is the documentation link:

https://developer.paypal.com/docs/api/payments.billing-plans/v1/#billing-plans_list

Basically just trying to pull a list of all my PayPal subscriptions, but it looks like I'm not sending something in JSON correctly...

Since you are sending a POST request, the API believes you are attempting to create a billing plan, and that being the case, your post data is expected to be in json form - which it is not.

According to the docs, to list your plans, the request type should be GET. So you need to add your params in the url:

curl_setopt($pp, CURLOPT_URL, "https://api.paypal.com/v1/payments/billing-plans?page_size=3&status=ALL&page=1&total_required=yes");

And remove these two lines:

curl_setopt($pp, CURLOPT_POST, true);
curl_setopt($pp, CURLOPT_POSTFIELDS, "page_size=3&status=ALL&page=1&total_required=yes");

It's important to understand that many RESTful APIs use the request types to differentiate between actions on the same endpoint. PATCH, POST, PUT, GET and DELETE requests may all have different meanings depending on the API.