Advanced Programming Language: Unit I :Chapter 2 -Handling Html Form with Php

Syllabus

Chapter 2 Handling Html Form with Php

2.1 Capturing Form Data

2.2 Dealing with Multi-value filed

2.3 Generating File uploaded form

2.4 Redirecting a form after submission

HTML Form:

The HTML <form> element defines a form that is used to collect user input:

<form>
.
form elements.

.
</form>

An HTML form contains form elements.

Form elements are different types of input elements, like text fields, checkboxes, radio buttons, submit buttons, and more.

The <input> Element:

The <input> element is the most important form element.

The <input> element can be displayed in several ways, depending on the type attribute.

Here are some examples:

Type	Description
<input type="text">	Defines a one-line text input field
<input type="radio">	Defines a radio button (for selecting one of many choices)
<input type="submit">	Defines a submit button (for submitting the form)

Example:

<html>

<body>

<form>

First name:<br>

Last name:<br>

<input type="radio" name="gender" value="female"> Female<br>

<input type="radio" name="gender" value="other"> Other <br>

</form>

</body>

</html>

2.1 Capturing Form Data

First of all, the form's action attribute needs to contain the URL of the PHP script that will handle the form.

For example:

When users send their forms, their data is sent to the server and the form_handler.php script is run.

The script then needs to read the form data and act on it.

Superglobal Array	Description
$_GET	Contains a list of all the field names and values sent by a form using the get method
$_POST	Contains a list of all the field names and values sent by a form using the post method
$_REQUEST	Contains the values of both the $_GET and $_POST arrays combined, along with the values of the $_COOKIE superglobal array

Each of these three superglobal arrays contains the field names from the sent form as array keys, with the field values themselves as array values.

For example, suppose you created a form using the get method, and that form contained the following control:

You could then access the value that the user entered into that form field using either the $_GET or the $_REQUEST superglobal:

$email = $_GET["emailAddress"];

$email = $_REQUEST["emailAddress"];

Example

In this example, you create a simple user registration form, then write a form handler script that reads the field values sent from the form and displays them in the page.

First, create the registration form.

Save the following HTML code as capformdata.html in your document root folder:

<html>

<body>

<label for="firstName">First name</label>

<label for="genderFemale">female?</label>

</form>

</body>

</html>

Next, save the following script as capformdata.php in your document root, the folder where you placed capformdata.html.

<html>

<body>

<?php

$first=$_GET["firstName"];

$last=$_GET["lastName"];

$sex=$_GET["gender"];

if($sex == "F")

echo "$first $last is a female.<br />";

else

echo "$first $last is a male.<br />";

</body>

</html>

Fill in the fields in the form, then click the Submit button.

If all goes well, you should see a page displaying the data that you just entered.

the process of capturing and displaying the submitted form data is really quite simple.

Because the form is sent using the post method, the script extracts the form field values from the $_POST superglobal array, and displays each field value using echo.

2.2 Dealing with Multi-value filed

The following form fields are capable of sending multiple values to the server:

<html>

<body>

<h2> <label>Enter Your Name: </label></h2>

<h2>What whould like to eat?</h2>

<label>Apple</label>

<label>Banana</label>

<label>Jackfruit</label>

<label>Orange</label>

<label>Mango</label>

<h2>What are your favorite soft drink?</h2>

<option value="sprite">Sprite</option>

<option value="orange juice">Orange Juice</option>

<option value="apple juice">Apple Juice</option>

<option value="water">Water</option>

</select>

<p>Note that hold a <b>ctrl</b> key to choose more than one item.</p>

</form>

</body>

</html>

Php script to process multiple values:

<html>

<body>

<?php

$fruitlist=$_POST["fruit"]; //assign an array to a local array

$favorlist=$_POST["favor"];

$name=$_POST["Name"];

echo $name." Your favorite drink from checkboxes are <br />";

foreach($fruitlist as $fruit)

echo $fruit . "<br /> ";

echo "<br />";

echo $name." Your favorite drink from pull-down menu are <br /> ";

foreach($favorlist as $favor)

echo $favor. "<br />";

</body>

</html>

2.3 Generating File uploaded form

move_uploaded_file() : Moves an uploaded file to a new location.

syntax:

move_uploaded_file ( string $filename , string $destination )

This function checks to ensure that the file designated by filename is a valid upload file (meaning that it was uploaded via PHP's HTTP POST upload mechanism). If the file is valid, it will be moved to the filename given by destination.

formtoup.html

Choose a file to upload: <input name="uploadedfile" type="file" /><br />

</form>

formtoup.php

<?php

$target_path = "d:/uploads/";

$target_path = $target_path . basename( $_FILES['uploadedfile']['name']);

if(move_uploaded_file($_FILES['uploadedfile']['tmp_name'], $target_path)) {

echo "The file ". basename( $_FILES['uploadedfile']['name']).

" has been uploaded";

} else{

echo "</br>There was an error uploading the file, please try again!";

}

Uploading Files with PHP
In this tutorial we will learn how to upload files on remote server using a Simple HTML form and PHP. You can upload any kind of file like images, videos, ZIP files, Microsoft Office documents, PDFs, as well as executables files and a wide range of other file types.

Step 1: Creating an HTML form to upload the file

The following example will create a simple HTML form that can be used to upload files.

<html>
<head>
<title>File Upload Form</title>
</head>
<body>
<form action="upmanager.php" method="post" enctype="multipart/form-data">
<h2>Upload File</h2>
<label for="fileSelect">Filename:</label>
<input type="file" name="photo" id="fileSelect">
<input type="submit" name="submit" value="Upload">
<p><strong>Note:</strong> Only .jpg, .jpeg, .gif, .png formats allowed to a max size of 5 MB.</p>
</form>
</body>
</html>

Note: In addition to a file-select field the upload form must use the HTTP post method and must contain an enctype="multipart/form-data" attribute. This attribute ensures that the form data is encoded as mulitpart MIME data — which is required for uploading the large quantities of binary data such as image, audio, video, etc

Step 2: Processing the uploaded file

Here's the complete code of our "upload-manager.php" file. It will store the uploaded file in a "upload" folder on permanent basis as well as implement some basic security check like file type and file size to ensure that users upload the correct file type and within the allowed limit.

<?php
// Check if the form was submitted
if($_SERVER["REQUEST_METHOD"] == "POST"){
// Check if file was uploaded without errors
if(isset($_FILES["photo"]) && $_FILES["photo"]["error"] == 0){
$allowed = array("jpg" => "image/jpg", "jpeg" => "image/jpeg", "gif" => "image/gif", "png" => "image/png");
$filename = $_FILES["photo"]["name"];
$filetype = $_FILES["photo"]["type"];
$filesize = $_FILES["photo"]["size"];

// Verify file extension
$ext = pathinfo($filename, PATHINFO_EXTENSION);
if(!array_key_exists($ext, $allowed)) die("Error: Please select a valid file format.");

// Verify file size - 5MB maximum
$maxsize = 5 * 1024 * 1024;
if($filesize > $maxsize) die("Error: File size is larger than the allowed limit.");

// Verify MYME type of the file
if(in_array($filetype, $allowed)){
// Check whether file exists before uploading it
if(file_exists("upload/" . $filename)){
echo $filename . " is already exists.";
} else{
move_uploaded_file($_FILES["photo"]["tmp_name"], "d:/uploads/" . $filename);
echo "Your file was uploaded successfully.";
}
} else{
echo "Error: There was a problem uploading your file. Please try again.";
}
} else{
echo "Error: " . $_FILES["photo"]["error"];
}
}
?>

Note: The above script prevents uploading a file with the same name as an existing file in the same folder. However, if you want to allow this just prepend the file name with a random string or timestamp, like $filename = time() . '_' . $_FILES["photo"]["name"];

You might be wondering what this code was all about. Well, let's go through each part of this example code one by one for a better understanding of this process.

Explanation of Code

Once the form is submitted information about the uploaded file can be accessed via PHP superglobal array called $_FILES. For example, our upload form contains a file select field called photo (i.e. name="photo"), if any user uploaded a file using this field, we can obtains its details like the name, type, size, temporary name or any error occurred while attempting the upload via the $_FILES["photo"] associative array, like this:

$_FILES["photo"]["name"] — This array value specifies the original name of the file, including the file extension. It doesn't include the file path.

$_FILES["photo"]["type"] — This array value specifies the MIME type of the file.

$_FILES["photo"]["size"] — This array value specifies the file size, in bytes.

$_FILES["photo"]["tmp_name"] — This array value specifies the temporary name including full path that is assigned to the file once it has been uploaded to the server.

$_FILES["photo"]["error"] — This array value specifies error or status code associated with the file upload, e.g. it will be 0, if there is no error.

2.4 Redirecting a form after submission

URL redirection is often used within form handling code.

Normally when you run a PHP script — whether by typing its URL, following a link, or submitting a form — the script does its thing, displays some sort of response as a Web page, and exits.

However, by sending a special HTTP header back to the browser from the PHP script, you can cause the browser to jump to a new URL after the script has run.

This is commonly used within a form handler script to redirect the users to a thank - you page after they ’ ve submitted the form.

This means that you can keep your thank - you page separate from your PHP script, which makes the page easier to edit and update.

Another good thing about redirecting to a new URL after a form has been submitted is that it prevents users from accidentally resubmitting the form by clicking their browser ’ s Reload or Refresh button.

Redirection is as simple as outputting a Location: HTTP header, including the URL you want to

redirect to. You output HTTP headers in PHP using the built - in header() function. So here ’ s how to redirect to a page called thanks.html :

header( “Location: thanks.html” );

The only thing to watch out for is that you don’t output any content to the browser — whether via echo() or print() , or by including HTML markup outside the < ?php ... ?> tags — before calling

header() . This is because the moment you send content to the browser, the PHP engine automatically sends the default HTTP headers — which won’t include your Location: header — and you can send headers only once per request.

Here’s a quick example of a form handler script that redirects to a thank - you page:

<?php

if ( isset( $_POST["submitButton"] ) ) {

// (deal with the submitted fields here)

header( "Location: thanks.html" );

exit;

} else {

displayForm();

}

function displayForm() {

<html>

<head>

<title>Membership Form</title>

</head>

<body>

<h1>Membership Form</h1>

<label for="firstName">First name</label>

<input type="submit" name="submitButton" id="submitButton" value=

"Send Details" />

</div>

</form>

</body>

</html>

<?php

}

Notice that the script doesn’t output anything to the browser until either the header() function is called, or until the membership form is displayed. Also notice that the script terminates with the exit statement after calling header() to avoid sending any further output to the browser.

Advanced Programming Language

Monday, 23 December 2019

Unit I :Chapter 2 -Handling Html Form with Php

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