PHPでStructured Outputs【OpenAI API】

Function Callingとresponse_formatの二つのやり方があるが、ここではresponse_formatを使ったやり方

<?php

function callOpenAIWithCurl(string $userInput, string $apiKey, string $url): array|string
{


    $postData = [
        "model" => "gpt-4o-mini",
        "messages" => [
            [
                "role" => "system",
                "content" => "あなたは賢いアシスタントです。"
            ],
            [
                "role" => "user",
                "content" => $userInput
            ]
        ],
        "response_format" => [
            "type" => "json_schema",
            "json_schema" => [
                "name" => "reasoning_schema", //スキーマに名前。APIの動作には影響しない
                "strict" => true, //レスポンスがこのスキーマに厳密に一致することを要求
                "schema" => [ //データの構造を定義
                    "type" => "object",
                    "properties" => [
                        "reasoning_steps" => [
                            "type" => "array",
                            "items" => [
                                "type" => "string"
                            ],
                            "description" => "最終結論に至る推論のステップ"
                        ],
                        "answer" => [
                            "type" => "string",
                            "description" => "推論のステップを考慮した最終的な答え"
                        ]
                    ],
                    "required" => ["reasoning_steps", "answer"],
                    "additionalProperties" => false
                ]
            ]
        ]
    ];

    

    $ch = curl_init($url);

    curl_setopt_array($ch, [
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_POST => true,
        CURLOPT_HTTPHEADER => [
            "Content-Type: application/json",
            "Authorization: Bearer " . $apiKey
        ],
        CURLOPT_POSTFIELDS => json_encode($postData)
    ]);

    $response = curl_exec($ch);

    if ($response === false) {
        $error = curl_error($ch);
        curl_close($ch);
        return "cURLエラー: " . $error;
    }

    $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    curl_close($ch);

    if ($httpCode !== 200) {
        return "HTTPエラー: $httpCode - " . $response; // レスポンス全体を返す
    }

    $responseData = json_decode($response, true);
    if (json_last_error() !== JSON_ERROR_NONE) {
        return "JSONデコードエラー: " . json_last_error_msg() . " - Response: " . $response;
    }

    if (!isset($responseData['choices'][0]['message']['content'])) {
        return "レスポンスの形式が不正です: " . $response;
    }

    $content = json_decode($responseData['choices'][0]['message']['content'], true);

    if (json_last_error() !== JSON_ERROR_NONE) {
        return "contentのJSONデコードエラー: " . json_last_error_msg() . " - Content: " . $responseData['choices'][0]['message']['content'];
    }

    return $content;
}

// 実行例
$apiKey = your_apikey;
$url = 'https://api.openai.com/v1/chat/completions';
$userInput = "9.11 と 9.9では、どちらが大きいか？";

$result = callOpenAIWithCurl($userInput, $apiKey, $url);


print_r($result); 


echo "<br><br>";

if (is_array($result)) {
    echo "ステップ：" . print_r($result['reasoning_steps']) . PHP_EOL;
    echo "答え：" . $result['answer'] . PHP_EOL;
} else {
    echo $result . PHP_EOL;
}
?>

JSONスキーマ部分を別の変数にする場合。

    // スキーマ部分を変数に格納
    $schema = [
        "schema" => [
            "type" => "object",
            "properties" => [
                "reasoning_steps" => [
                    "type" => "array",
                    "items" => [
                        "type" => "string"
                    ],
                    "description" => "最終結論に至る推論のステップ"
                ],
                "answer" => [
                    "type" => "string",
                    "description" => "推論のステップを考慮した最終的な答え"
                ]
            ],
            "required" => ["reasoning_steps", "answer"],
            "additionalProperties" => false
        ]
    ];

    $postData = [
        "model" => "gpt-4o-mini",
        "messages" => [
            [
                "role" => "system",
                "content" => "あなたは賢いアシスタントです。"
            ],
            [
                "role" => "user",
                "content" => $userInput
            ]
        ],
        "response_format" => [
            "type" => "json_schema",
            "json_schema" => array_merge([ // array_mergeを使用
                "name" => "reasoning_schema", //スキーマに名前。APIの動作には影響しない
                "strict" => true, //レスポンスがこのスキーマに厳密に一致することを要求
            ], $schema)
        ]
    ];