Correct Methods for Sending Raw JSON Data in Postman and PHP Backend Processing Mechanisms

Analysis of JSON Data Transmission Issues in Postman

When using Postman to send POST requests, many developers encounter a common problem: although the JSON-formatted request body is correctly set, the data cannot be retrieved using $_POST in the PHP backend. The fundamental reason for this phenomenon lies in the differences in data parsing mechanisms.

Comparison of Data Transmission Mechanisms Between jQuery and Postman

When using jQuery's $.ajax method, by default jQuery serializes JavaScript objects into application/x-www-form-urlencoded format. This format of data is automatically parsed by PHP and populated into the $_POST array. Example code:

$.ajax({
    "type": "POST",
    "url": "/rest/index.php",
    "data": {
        "foo": "bar"
    }
})

However, when selecting "raw" mode in Postman and specifying application/json, raw JSON strings are sent. This format of data is not automatically parsed by PHP into the $_POST array because $_POST is specifically designed for handling form data.

Correct Methods for Handling Raw JSON Data in PHP

To properly handle raw JSON data sent from Postman, PHP's php://input stream and json_decode function must be used. php://input is a read-only stream that allows reading raw data from the request body. Complete processing code:

$json_data = file_get_contents("php://input");
$data = json_decode($json_data, true);
print_r($data);

Here, the second parameter of json_decode is set to true, indicating that JSON objects should be converted to associative arrays, maintaining consistency with the data structure of $_POST.

Correct Configuration Methods in Postman

When sending JSON data in Postman, ensure the following configuration:

• Select the "raw" option in the Body tab
• Choose "JSON" format from the dropdown menu
• Add Content-Type: application/json in Headers
• Enter valid JSON data in the body area

Configuration Methods for Sending Raw JSON in jQuery

If you need to simulate Postman's behavior in jQuery and send raw JSON data, use the following configuration:

$.ajax({
    "url": "/rest/index.php",
    "data": JSON.stringify({foo: 'bar'}),
    "type": "POST",
    "contentType": "application/json"
});

The key here is using JSON.stringify() to convert JavaScript objects to JSON strings and explicitly setting contentType to application/json.

Differences Between Form Data and Raw JSON Data

If you wish to continue using $_POST to retrieve data, you can select "form-data" or "x-www-form-urlencoded" mode in Postman and send data in the format foo=bar&foo2=bar2. Data in this format will be automatically parsed by PHP into the $_POST array.

Practical Application Scenarios and Best Practices

In actual development, it is recommended to choose the appropriate data format based on API design specifications:

• For RESTful APIs, JSON format is typically used for data exchange
• For traditional form submissions, use application/x-www-form-urlencoded format
• In the PHP backend, decide which parsing method to use based on the Content-Type header

By understanding these underlying mechanisms, developers can more flexibly handle different types of HTTP requests, ensuring accuracy and efficiency in frontend-backend data interactions.