如何在PHP中读取JSON ArrayList数据？报错问题求助

The error you're hitting comes down to a simple mix-up: you're trying to use PDO's fetch() method on decoded JSON data, but json_decode() returns a standard PHP object (or array), not a database query result set. The fetch() method only works with PDO statement objects, not JSON data.

Let's break down the problem and fix it step by step: #

Your input JSON is an object containing an orderHistory array of products. When you run json_decode(file_get_contents("php://input")), you get a stdClass object where the orderHistory property holds your product list. Instead of using a while loop with fetch(), you need to loop directly through this array.

Corrected Code: Object Syntax #

// Get posted JSON data and decode as an object
$data = json_decode(file_get_contents("php://input"));

// First, validate the input to avoid errors
if (isset($data->orderHistory) && is_array($data->orderHistory)) {
    // Loop through each product in the orderHistory array
    foreach ($data->orderHistory as $product) {
        // Access individual product properties
        $name = $product->product_name;
        $price = $product->product_price;
        $id = $product->product_id;
        
        // Example: Output product details (adjust this to your needs)
        echo json_encode([
            "message" => "Product processed",
            "product" => [
                "id" => $id,
                "name" => $name,
                "price" => $price
            ]
        ]) . "\n";
    }
} else {
    // Handle cases where input is missing or malformed
    echo json_encode(["message" => "Invalid or missing order history data"]);
}

Alternative: Array Syntax (if you prefer working with arrays) #

Pass true as the second parameter to json_decode() to get an associative array instead of an object:

// Decode JSON as an associative array
$data = json_decode(file_get_contents("php://input"), true);

// Validate input
if (isset($data['orderHistory']) && is_array($data['orderHistory'])) {
    foreach ($data['orderHistory'] as $product) {
        // Access product data using array keys
        $name = $product['product_name'];
        $price = $product['product_price'];
        $id = $product['product_id'];
        
        // Do something with the data (example output)
        echo "Processed product: $name (ID: $id, Price: $price)\n";
    }
} else {
    echo json_encode(["message" => "No valid order history found"]);
}

Key Takeaways: #

• Always validate input: Check if the expected properties exist (using isset()) and are the correct type (like is_array() for orderHistory). This prevents errors if the JSON is malformed or missing data.
• fetch() is for databases only: Use foreach() loops to iterate over JSON arrays, not PDO methods. PDO's fetch() is meant for retrieving rows from database query results.

内容的提问来源于stack exchange，提问作者learner