Using PHP to access ChatGPT API

Question

I'm writing a simple PHP script with no dependencies to access the ChatGPT API, but it's throwing an error I don't understand:

Here's the script so far:

    $apiKey = "Your-API-Key";
    $url = 'https://api.openai.com/v1/chat/completions';  
    
    $headers = array(
        "Authorization: Bearer {$apiKey}",
        "OpenAI-Organization: YOUR-ORG-STRING", 
        "Content-Type: application/json"
    );
    
    // Define messages
    $messages = array();
    $messages["role"] = "user";
    $messages["content"] = "Hello future overlord!";
    
    // Define data
    $data = array();
    $data["model"] = "gpt-3.5-turbo";
    $data["messages"] = $messages;
    $data["max_tokens"] = 50;

    // init curl
    $curl = curl_init($url);
    curl_setopt($curl, CURLOPT_POST, 1);
    curl_setopt($curl, CURLOPT_POSTFIELDS, json_encode($data));
    curl_setopt($curl, CURLOPT_HTTPHEADER, $headers);
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
    
    $result = curl_exec($curl);
    if (curl_errno($curl)) {
        echo 'Error:' . curl_error($curl);
    } else {
        echo $result;
    }
    
    curl_close($curl);

This returns an error from the API:

{"model":"gpt-3.5-turbo","messages":{"role":"user","content":"Hello future overlord!"},"max_tokens":50}{ "error": { "message": "{'role': 'user', 'content': 'Hello future overlord!'} is not of type 'array' - 'messages'", "type": "invalid_request_error", "param": null, "code": null } }

AFAIK, I'm sending the messages param as an array. Where is this going wrong? Is this an issue with json_encode? Why doesn't the API think this is an array?

Thanks in advance!

Answer 1

Ah... I see the issue... Leaving this answer here if anyone else has the same issue:

There are two distinct parameters, "message" and "messages". I didn't notice the singluar / plural in the error message.

Corrected code is here:

// Define messages
$messages = array();
$message = array();
$message["role"] = "user";
$message["content"] = "Hello future overlord!";
$messages[] = $message;

// Define data
$data = array();
$data["model"] = "gpt-3.5-turbo";
$data["messages"] = $messages;
$data["max_tokens"] = 50;

Thanks everyone above for the comments.

Answer 2

<?php
$apiKey = "API KEY";
$model = "text-davinci-003";
$prompt = $_POST['prompt'];
$temperature = 0.7;
$maxTokens = 256;
$topP = 1;
$frequencyPenalty = 0;
$presencePenalty = 0;

$data = array(
    'model' => $model,
    'prompt' => $prompt,
    'temperature' => $temperature,
    'max_tokens' => $maxTokens,
    'top_p' => $topP,
    'frequency_penalty' => $frequencyPenalty,
    'presence_penalty' => $presencePenalty
);

$ch = curl_init();

curl_setopt($ch, CURLOPT_URL, "https://api.openai.com/v1/completions");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($data));
curl_setopt($ch, CURLOPT_HTTPHEADER, array("Content-Type: application/json", "Authorization: Bearer " . $apiKey));

$response = curl_exec($ch);

if (curl_errno($ch)) {
    echo 'Error: ' . curl_error($ch);
} else {
    $jsonResponse = json_decode($response, true);
    $generatedText = '';
    var_dump($jsonResponse);die();
    if (isset($jsonResponse['choices']) && count($jsonResponse['choices']) > 0 && isset($jsonResponse['choices'][0]['text'])) {
        $generatedText = $jsonResponse['choices'][0]['text'];
    } else {
        $generatedText = 'No response generated.';
    }
  
    $sentences = preg_split('/(?<=[.?!])\s+(?=[a-z])/i', $generatedText);
    $numSentences = count($sentences);
    $paragraphs = array();
    $curParagraph = '';
    for ($i = 0; $i < $numSentences; $i++) {
        $curParagraph .= $sentences[$i] . ' ';
        if (($i + 1) % 3 == 0) {
            array_push($paragraphs, $curParagraph);
            $curParagraph = '';
        }
    }
    if ($curParagraph != '') {
        array_push($paragraphs, $curParagraph);
    }
    foreach ($paragraphs as $paragraph) {
        echo "<p>" . trim($paragraph) . "</p>" . "<br>";
    }
}

curl_close($ch);
?>