如何使用单个整数值创建PHP json对象？

Question

I need to create a PHP json object like { 12345 } and post it through cURL, but my code:

$json = json_encode(array($CaseID), JSON_FORCE_OBJECT);

returns a string "{"0":"15876285"}" representing an associative array.

public function RetrieveCase($CaseID) {

   $json = json_encode(array($CaseID), JSON_FORCE_OBJECT);

   //*** FOR DEBUG ONLY
   $f = fopen('sti_error.log', 'w');

   $curl = curl_init($this->signifyd_api_endpoint);

   curl_setopt($curl, CURLOPT_HEADER, true);
   curl_setopt($curl, CURLOPT_HTTPHEADER, array('Content-Type: application/json', 'Content-Length: ' . strlen($json)));
   curl_setopt($curl, CURLOPT_USERPWD, $this->signifyd_trans_key . ":");
   curl_setopt($curl, CURLOPT_POST, true);
   curl_setopt($curl, CURLOPT_POSTFIELDS, $json);
   curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);
   curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);   // Return response instead of printing.
   curl_setopt($curl, CURLOPT_TIMEOUT, 3);
   curl_setopt($curl, CURLOPT_CONNECTTIMEOUT, 3);
   curl_setopt($curl, CURLOPT_VERBOSE, 1);  //** FOR DEBUG ONLY
   curl_setopt($curl, CURLOPT_STDERR, $f);
   curl_setopt($curl, CURLOPT_HEADER, 1);  //** FOR DEBUG ONLY
   curl_setopt($curl, CURLINFO_HEADER_OUT, true);  //** FOR DEBUG ONLY        

   //** For debg only
   $fp = fopen ("sti_output.log", "w") or die("Unable to open stdout for writing.
"); 
   curl_setopt($curl, CURLOPT_FILE, $fp); 

   $response = curl_exec($curl);

   if (!$response) {
       $this->session->data['error'] = 'SIGNIFYD RetrieveCase failed: ' . curl_error($curl) . '(#' . curl_errno($curl) . ')';
       curl_close($curl);
       return false;
   }

   $httpcode = curl_getinfo($curl, CURLINFO_HTTP_CODE);

   curl_close($curl);

   fclose($f);

   //$this->load->language('payment/signifyd_transaction_investigation');
   // HHTP Status Code 201 CREATED - The resource requested was successfully created.                
   if ($httpcode != '201') {
       return $this->getCase($response);
   }
   $this->session->data['error'] = 'SIGNIFYD RetrieveCase failed response: ' . $response;
   return false;    }

Answer 1

@Barmar, thanks to you response I finally got past my moment of confusion. Let me explain – I was reading the endpoint code line example on SIGNIFYD API docs and, between PHP, JSON and SIGNIFYD API, I got confused with {CASE_ID} notation. Because the initial API call (Create Case) was a POST with JSON POSTFIELDS, I mistakenly assumed {CASE_ID} notation and a PHP encoded JSON with a single integer. Truth be told I didn't pay much attention to the API docs where this (Retrieve Case) call is a GET and the https://api.signifyd.com/v2/cases/{CASE_ID} endpoint should have the CASE_ID without the curly-brackets – in other words, this API call only receives a JSON response but, does not send any JSON at all. Silly me!

This is the working version of the method. You also can see the complete class in https://github.com/mdutra555/SIGNIFYD_API_OpenCart_Model

public function RetrieveCase($CaseID) {

    //** From SIGNIFYD API Docs
    //        GET https://api.signifyd.com/v2/cases/{CASE_ID}    ****** beware of this {CASE_ID} notation, the {} curly-brackets must not be used.
    //   Plese note that "Retrieving a case" uses GET, unlike "Creating a new case" uses POST method.

    $url = $this->signifyd_api_endpoint . '/' . $CaseID;
    $curl = curl_init();
    curl_setopt($curl, CURLOPT_URL, $url);    
    curl_setopt($curl, CURLOPT_HEADER, true);
    curl_setopt($curl, CURLOPT_HTTPHEADER, 'Content-Type: application/json');
    curl_setopt($curl, CURLOPT_USERPWD, $this->signifyd_trans_key . ":");
    curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);   // Use 1 for curl_exec() to return the response header + content. DO NOT USE true boolean, it will not work.
    curl_setopt($curl, CURLOPT_TIMEOUT, 3);
    curl_setopt($curl, CURLOPT_CONNECTTIMEOUT, 3);

    $response = curl_exec($curl);
    if (!$response) {
        $this->session->data['error'] = 'SIGNIFYD RetrieveCase failed: ' . curl_error($curl) . '(#' . curl_errno($curl) . ')';
        curl_close($curl);
        return false;
    }

    $httpcode = curl_getinfo($curl, CURLINFO_HTTP_CODE);

    curl_close($curl);

    // HHTP Status Code 200 OK - The resource requested was successfully returned.                
    if ($httpcode == '200') {
        return $this->getCase($response);
    }
    $this->session->data['error'] = 'SIGNIFYD RetrieveCase failed response: ' . $response;
    return false;
}