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Using PHP with Radio Buttons.

This is a beginner’s tutorial on how to use the Radio Button HTML element with PHP. In this example, we will be building a HTML form that contains a simple “Yes” / “No” choice. We will then process and validate the radio buttons using PHP.

HTML Radio Buttons.

Let’s take a look at the following HTML form:

Do you agree to our Terms & Conditions?

Yes No

The form above simply asks the user if they agree to our website’s Terms & Conditions. Two radio inputs are present in the form and they provide the user with a Yes or No choice.

It is important to note that none of the radio buttons in the form above are ticked by default. If you want to tick a radio button by default, then you will can use the checked attribute:

Processing and validating radio buttons with PHP.

A lot of beginner developers make the mistake of assuming that one of their radio buttons will be ticked. As a result, they end up with nasty undefined index errors.

Simply put: Your PHP code must be able to handle instances where no radio button was submitted. The user might not tick one of your radio buttons or worse: They might open up developer tools and remove the radio buttons altogether.

HTML forms can be easily modified. Therefore, you can never trust the client and you must validate everything.

Let’s take a look at the following PHP example:

//Check to see if the submit button was pressed. if(isset($_POST['submit_form'])) < //False unless proven otherwise. $agreedToTerms = false; //Make sure that a radio button input was actually submitted. if(isset($_POST['terms']))< //An array containing the radio input values that are allowed $allowedAnswers = array('yes', 'no'); //The radio button value that the user sent us. $chosenAnswer = $_POST['terms']; //Make sure that the value is in our array of allowed values. if(in_array($chosenAnswer, $allowedAnswers))< //Check to see if the user ticked yes. if(strcasecmp($chosenAnswer, 'yes') == 0)< //Set our variable to TRUE because they agreed. $agreedToTerms = true; >> > //If the user agreed if($agreedToTerms) < //Process the form, etc. >>

A few points above the PHP code above:

• We set a default option to fall back on if our radio button is not ticked or submitted by the client.
• Our code checks to see if a radio button value actually exists before attempting to process it. As I said above, if you fail to do this, there’s a good chance that your PHP code with throw undefined index errors.
• We created a whitelist array of acceptable values. This is important, as a user could modify the values of our radio buttons by using the developer tools feature on Chrome or Firefox. i.e. They could change “yes” to “hello”. Or even worse: They could enter SQL code, JavaScript or spam content in the hope that we store and display the radio input values without validating them.
• Once our PHP code has validated the radio input correctly, we process the form.

Creating a whitelist of acceptable values is especially important. Could you imagine if a user was able to change “yes” to “helicopter” in your TOS form?

Anyway, I hope you found this tutorial to be helpful!

Источник

Form input type radio php

Формы могут содержать различные элементы — текстовые поля, флажки, переключатели и т.д., обработка которых имеет свои особенности.

Обработка флажков

Флажки или чекбоксы (html-элемент ) могут находиться в двух состояниях: отмеченном (checked) и неотмеченном. Например:

Если флажок находится в неотмеченном состоянии, например:

то при отправке формы значение данного флажка не передается на сервер.

Если флажок отмечен, то при отправке на сервер для поля remember будет передано значение on :

Если нас не устраивает значение on , то с помощью атрибута value мы можем установить нужное нам значение:

Иногда необходимо создать набор чекбоксов, где можно выбрать несколько значений. Например:

     "; > ?> 
Форма ввода данных
 
ASP.NET: 
 
PHP: 
 
Node.js: 
   

В этом случае значение атрибута name должно иметь квадратные скобки. И тогда после отправки сервер будет получать массив отмеченных значений:

$technologies = $_POST["technologies"]; foreach($technologies as $item) echo "$item
";

В данном случае переменная $technologies будет представлять массив, который можно перебрать и выполнять все другие операции с массивами.

Переключатели

Переключатели или радиокнопки позволяют сделать выбор между несколькими взаимоисключающими вариантами:

      ?> 
Форма ввода данных
 ASP.NET 
PHP 
Node.js 

На сервер передается значение атрибута value у выбранного переключателя. Получение переданного значения:

Список

Список представляет элемент select , который предоставляет выбор одного или нескольких элементов:

      ?> 
Форма ввода данных
  ASP.NET PHP RUBY Python    

Элемент содержит ряд вариантов выбора в виде элементов :

Получить выбранный элемент в коде PHP как и обычное одиночное значение:

Но элемент также позволяет сделать множественный выбор. И в этом случае обработка выбранных значений изменяется, так как сервер получает массив значений:

     "; > ?> 
Форма ввода данных
  ASP.NET PHP RUBY Python   

Такие списки имеют атрибут multiple=»multiple» . Для передачи массива также указываются в атрибуте name квадратные скобки: name=»courses[]»

Источник

PHP Radio Button

Summary: in this tutorial, you’ll learn how to create a form with radio buttons and handle radio groups in PHP.

Introduction to radio buttons

To create a radio button, you use the element with the type radio . For example:

input type="radio" name="contact" id="contact_email" value="email" />Code language: HTML, XML (xml)

A radio button doesn’t have a label. Therefore, you should always use a radio button with a element like this:

input type="radio" name="contact" id="contact_email" value="email"/> label for="contact_email">Email label>Code language: HTML, XML (xml)

To associate a radio button with a element, the value of the for attribute of the label needs to be the same as the value of the id of the radio button.

A radio button has two states: checked and unchecked.

When you link a label with a radio button, you can check the radio button by clicking the label or the radio button itself. Hence, the label increases the usability of the radio button because it expands the selection area.

Alternatively, you can place the radio button within a element like this:

label> input type="radio" name="contact_email" value="email"> Email label>Code language: HTML, XML (xml)

In this case, the radio links to the label without matching the for and id attributes.

To select a radio button automatically when the page loads for the first time, you can use the checked Boolean attribute:

input type="radio" name="contact" id="contact_email" value="email" checked /> label for="contact_email">Email label>Code language: HTML, XML (xml)

Define a radio group

In practice, you often use the radio buttons in a group. A group of radio buttons is called a radio group. A radio group allows you to select only one radio button at a time.

If you select any radio button in a group, the currently-selected radio button in the same group is automatically deselected.

To define a radio group, you assign the same name to all the radio buttons in the same group.

The following example defines a radio group that consists of two radio buttons.

input type="radio" name="contact" id="contact_email" value="email" /> label for="contact_email">Email label> input type="radio" name="contact" id="contact_phone" value="phone" /> label for="contact_phone">Phone label>Code language: HTML, XML (xml)

Handle radio buttons in PHP

When a form has a radio button with a name, you can get the checked radio button by accessing either $_POST or $_GET array, depending on the request method.

If a radio button is not checked, the $_POST or $_GET does not contain the key of the radio button. Therefore, you need to use the isset() function to check whether a radio button is checked or not:

isset($_POST['radio_name'])Code language: PHP (php)

Alternatively, you can use the filter_has_var() function:

filter_has_var(INPUT_POST, 'radio_name')Code language: JavaScript (javascript)

The filer_has_var() returns true if it finds the radio button name in the INPUT_POST .

If a radio button is checked, you get the value of the radio button from the $_POST using the radio button name:

$_POST['radio_name']Code language: PHP (php)

PHP radio button example

We’ll create a simple form with a radio group. If you do not select any option and submit the form, it’ll show an error message. Otherwise, it’ll show the value of the selected radio button.

First, create the following directory and file structure:

. ├── css | └── style.css ├── inc | ├── footer.php | ├── get.php | ├── header.php | └── post.php └── index.phpCode language: plaintext (plaintext)

Second, add the following code to the header.php file:

html> html lang="en"> head> meta charset="UTF-8" /> meta name="viewport" content="width=device-width, initial-scale=1.0" /> title>PHP Radio Button title> link rel="stylesheet" href="css/style.css"> head> body> main>Code language: HTML, XML (xml)

Third, add the following code to the footer.php file:

 main> body> html>Code language: HTML, XML (xml)

Fourth, add the following code to the index.php file:

 require __DIR__ . '/inc/header.php'; $contacts = [ 'email' => 'Email', 'phone' => 'Phone' ]; $errors = []; $request_method = strtoupper($_SERVER['REQUEST_METHOD']); if ($request_method === 'GET') < require __DIR__ . '/inc/get.php'; > elseif ($request_method === 'POST') < require __DIR__ . '/inc/post.php'; > require __DIR__ . '/inc/footer.php'; Code language: PHP (php)

The $contacts array is used to generate radio buttons dynamically. In a real application, the data may come from a database table or a result of an API call.

The $errors array is used to collect the error messages.

To get the HTTP request method, you access the ‘REQUEST_METHOD’ key of the $_SERVER array. The strtoupper() function converts the request method to uppercase.

$request_method = strtoupper($_SERVER['REQUEST_METHOD']);Code language: PHP (php)

The index.php file loads the get.php from the inc directory if the request is GET. When the form is submitted with the POST request, the index.php loads the post.php from the inc directory:

if ($request_method === 'GET') < require __DIR__ . '/inc/get.php'; > elseif ($request_method === 'POST') < require __DIR__ . '/inc/post.php'; >Code language: PHP (php)

Fifth, create a form in the get.php file:

"" method="post"> 
Please choose your preferred method of contact:
  foreach ($contacts as $key => $value) : ?> 
"radio" name="contact" >"contact_" value="" /> for="contact_"> echo $value ?> 
  endforeach ?> 
class hljs-title">error">php echo $errors['contact'] ?? '' ?>small> div> div> button type hljs-title">submit">Submitbutton> div> form>Code language: PHP (php)

 foreach ($contacts as $key => $value) : ?> 
"radio" name="contact" >"contact_" value="" /> for="contact_">  echo $value ?>  
  endforeach ?>Code language: PHP (php)

class hljs-title">error">php echo $errors['contact'] ?? '' ?>small>Code language: PHP (php)

 // sanitize the contact $contact = filter_input(INPUT_POST, 'contact', FILTER_SANITIZE_STRING); // check the selected value against the original values if ($contact && array_key_exists($contact, $contacts)) < $contact = htmlspecialchars($contact); >else < $errors['contact'] = 'Please select at least an option.'; > if (count($errors)) < require __DIR__ . '/get.php'; > else < echo  $contact. Back to the form html; > Code language: PHP (php)