Getting Started with PHP: POST Requests and Responses-PHP Tutorial-php.cn

Getting Started with PHP: POST Requests and Responses

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Release： 2023-05-20 17:54:02

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In web development, interactive applications allow users to interact with the website. The HTTP protocol is designed to transfer data between servers and clients. PHP is a web development language that can be used to handle HTTP requests and responses.

This article will introduce how to use PHP to handle POST requests and responses. First, we'll briefly introduce how the HTTP protocol works, and then discuss how to handle POST requests and responses using PHP's built-in functions. Finally, we'll discuss some best practices to ensure your code is safe and effective.

HTTP protocol

HTTP protocol is one of the most important protocols in web development. When a user types a URL into a browser and presses the Enter key, the browser communicates with the web server using the HTTP protocol. The HTTP protocol uses the concepts of requests and responses to transmit data.

Request The request contains the following parts:

Request line
Request header (optional)
Request body (optional)

The request line specifies the method of the request (GET, POST, etc.), and the URI to be requested. Request headers contain additional information about the request, such as browser type, cookies, etc. The request body contains the transferred data (if any).

When the server receives the request, it processes the request and returns a response. The response consists of the following parts:

Status line
Response headers (optional)
Response body (optional)

The status line specifies the response's status code and reason phrase. Response headers contain additional information about the response such as server type, response type, etc. The response body contains the actual data transferred (if any).

POST request

POST request is a way to send data to the server. When a user enters data into a form and submits the form, the data is typically sent to the server in the form of a POST request. Here are the steps required to send a POST request from a form:

Create the form element in HTML
Set up the form's actions and methods
Wrap the form element in In a form tag

The following is a basic HTML form:

<html>
<head>
<title>POST请求演示</title>
</head>
<body>

<form action="process_form.php" method="POST">
名字: <input type="text" name="name"><br>
年龄: <input type="text" name="age"><br>
<input type="submit" value="提交">
</form>

</body>
</html>

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In this form, we use a script named "process_form.php" to process the form data . We also specified that the form will be submitted using the POST method, which means the data will be sent to the server in the form of a POST request.

PHP handles POST requests

PHP has some built-in functions to handle POST requests and responses. Here are some of the most common functions:

$_POST - A global variable used to store data sent via the POST method.
isset() - Used to determine if a variable has been set.
htmlspecialchars() - Used to prevent cross-site scripting attacks (XSS).

The following is a sample code that uses the above function to handle a POST request:

<html>
<head>
<title>处理POST请求</title>
</head>
<body>

<?php
if(isset($_POST['name']) && isset($_POST['age'])) {
  $name = htmlspecialchars($_POST['name']);
  $age = htmlspecialchars($_POST['age']);
  echo "你好，$name。你 $age 岁了。";
} else {
?>
  <form action="<?php echo $_SERVER['PHP_SELF'];?>" method="POST">
  名字: <input type="text" name="name"><br>
  年龄: <input type="text" name="age"><br>
  <input type="submit" value="提交">
  </form>
<?php
}
?>

</body>
</html>

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In this example, we use the $_POST variable to obtain the form data. We also used the isset() function to ensure that the data has been sent via the POST method. Finally, we used the htmlspecialchars() function to prevent cross-site scripting attacks.

Best Practices

Here are some best practices to ensure your code is safe and valid:

Check all input data and make sure they are valid of.
For data retrieved from the database, use parameterized queries to avoid SQL injection attacks.
For data generated from user input, use the htmlspecialchars() function to prevent cross-site scripting attacks.
Do not include sensitive information such as passwords and credit card numbers in the response.
Get enough permissions to perform the task, but don't give too much permissions.

Conclusion

In this article, we learned how to handle POST requests and responses using PHP. We learned how the HTTP protocol works, one of the most important protocols in web development. We also learned several important PHP built-in functions, such as $_POST, isset() and htmlspecialchars(). Finally, we discuss some best practices to ensure your code is safe and effective.

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