PHP script to remove e-mail addresses from a comma-separated list [closed]

Answer 1

This answer was originally appended to the question body by the OP.

First I moved the form to /cancel.html and used <form action="/cancel_submit.html">.

(Where I have written .html, it is just to demonstrate, as my server is configured to use no page extentions and also so that PHP is parsed on .html pages.)

Then I put the PHP code into the page /cancel_submit.html and moved

if ($str1 > $str2) {
    echo ("You Have Successfully Unsubscribed From Our Newsletter....<br>You Will Not Receive Any More Emails From Us.");
} else {
    echo ("The Email Address You Specified Is Not In Our Mailing List.");
}

to another set of PHP brackets.

This meant that the e-mail affffdress was sent via POST to the other page, which then performed the actual removal of the e-mail address from the list and then checked to see if an address been removed to provide the comfirmation message.

I also added two commas to $oldword = "$email"; to make it $oldword = ",$email,"; so that it only finds the text entered into the e-mail box if it has a comma on either side. This addresses the case where someone submits half of an e-mail address.

I also changed $newWord = ""; to $newWord = ","; so that if the script removes an e-mail address with commas at each side, the two e-mail addresses that were next to it will not be separated by a comma.

Here is the code I have for both pages now:

1. cancel.html

   <p>To cancel our Newsletter please enter your email address below....</p>
   <p>
   <form method="post" action="/cancel_submit.html">
   <p>Email Address: <input type="text" name="email"></p>
   <input type="submit" value="Cancel Newsletter" name="submit">
   </form>
   

2. cancel_submit.html

   <?php
       $email = $_POST["email"];
       $basetext = file_get_contents("email.txt");
       $oldWord = ",$email,";
       $newWord = ",";
       $text = str_replace($oldWord , $newWord , $basetext);
       $str1 = $basetext;
       // echo strlen($str1);
       $str2 = $text;
       // echo strlen($str2);
       $fp = fopen('email.txt', 'w');
       fwrite($fp, $text);
       fclose($file);
   ?>
   <?php
       if ($str1 > $str2) {
           echo ("You Have Successfully Unsubscribed From Our Newsletter....<br>You Will Not Receive Any More Emails From Us.");
       } else {
           echo ("The Email Address You Specified Is Not In Our Mailing List.");
       }
   ?>
   <p>
       <p>Please wait to be re-directed or <a href="http://the-flying-shuttle.com/"><u>CLICK HERE.</u></a>
       </p>
   

EDIT:

I made a few improvements. I added:

$email = strtolower($email);

to both the e-mail add script and the e-mail remove script. This converted all characters entered into either form to lowercase; previously, it wouldnt remove e-mails typed in a different case than the big list had.

This messed up the confirmation message command, so I changed it to

if (str_replace($oldWord , $newWord , $basetext)) {
    echo ("You Have Successfully Unsubscribed From Our Newsletter....<br>You Will Not Receive Any More Emails From Us.");
} else {
    echo ("The Email Address You Specified Is Not In Our Mailing List.");
}

Answer 2

In your sample you reference a variable $_POST['email'] without assignment or testing the value. Additionally you may want to sanitize this variable.

Another issue I saw was that $to_delete = 'email';, you are only looking for entries of 'email'.

Your $file_put_contents is not being assigned.

} else { showForm(); } wasn't paired up with an if statement.

<?php
function showForm() {
    echo '<form method="post" action="">' . PHP_EOL
       . 'Email Address: <input type="text" name="email"> <br />' . PHP_EOL
       . '<input type="submit" value="Cancel Newsletter" name="submit">' . PHP_EOL
       . '</form>';
}

if($_POST['email']) {

    $to_delete = $_POST['email'];
    $file = array_flip(explode(",",file_get_contents("email.txt")));
    unset($file[$to_delete]);
    $file_put_contents = file_put_contents("email.txt",implode(",",array_flip($file));

    if(!$file_put_contents) {
        die('Error occured');
    } else {
        echo 'Your subscription has been cancelled. You will not receive any further emails from us.';
    }
} else {
    showForm();
}

Answer 3

Suggested research:

http://us.php.net/manual/en/function.explode.php
http://us3.php.net/manual/en/function.file-put-contents.php
edited to add: http://us3.php.net/manual/en/function.file-get-contents.php

If you end up with a 3rd party service, don't pay Aweber. Go for MailChimp. They've got a free plan if your mailing list isn't that big.

Answer 4

If I understand your question correctly, this is what you are attempting to achieve.

• Check to see if the user has posted from a form.
  • Get the email. (You should ensure that it is a sane value in this step)
  • Retrieve the member data.
  • Check to see if the user is on the list.
    • Remove the user and save the data if applicable.
  • Output the result of the function.
• Display a message with form to submit to self.

I know this can be done as a very simple task, but I don't trust that approach. Additionally, I think anything interacting with permanent storage of data should have some mild to moderate form of abstraction.

I would approach that task this way.

class MailingList {

    const EMAIL_OK = 1;
    const ERR_EMAIL_EXISTS = -1;
    const ERR_EMAIL_INVALID = -2;
    const ERR_EMAIL_NOTFOUND = -3;

    protected $_db_src;
    protected $_db_opt;
    protected $members = array(); // An array intended to hold members.

    public function email_exists($email) {
        return array_key_exists($this->members, $email);
    }

    public function remove_email($email) {
        $this->_sanitize_email($email);

        if ($email) {
            if (array_key_exists($this->members, $email)) {
                unset($this->members[$email]);
                $this->_update_members();
                return self::EMAIL_OK;
            } else {
                return self::ERR_EMAIL_NOTFOUND;
            }
        } else {
            return self::ERR_EMAIL_INVALID;
        }
    }

    public function add_email($email) {
        $this->_sanitize_email($email);

        if ($email) {
            if (array_key_exists($this->members) {
                return self::ERR_EMAIL_EXISTS;
            } else {
                $this->members[$email] = -1;
                $this->_save_members();
                $this->_load_members();
                return self::EMAIL_OK;
            }
        } else {
            return self::ERR_EMAIL_INVALID;
        }
    }

    // We expect a data source and options for the
    //     data source upon instantiation.
    // This is to prepare this class for abstraction and allow it to be
    //     extended to databases.

    public function __construct($data_source = "flatfile", $data_options = "email.txt") {
        $this->_db_src = $data_source;
        $this->_db_opt = $data_options;

        $this->_load_members();
    }

    protected function _load_members() {
        // Create the function name to ensure it exists.
        $data_function = "handle_" . $this->_db_src;
        if (!method_exists(&$this, $this->_db_src)) {
            throw new Exception('Invalid data source');
        }

        // Build our array of parameters to be sent to our handler function.
        $parameters = array_merge(array('load'), (array) $this->_db_opt);

        // This calls our data function with a load action parameter.
        // This is written to expect the data function to populate $this->members.
        return call_user_func_array(array(&$this, $data_function), $parameters);
    }

    // Most of this is similar to the constructor as far as data handling goes.
    protected function _save_members() {
        // Create the function name to ensure it exists.
        $data_function = "handle_" . $this->_db_src;
        if (!method_exists(&$this, $this->_db_src)) {
            throw new Exception('Invalid data source');
        }

        // Set up our data options with a save action.
        $parameters = array_merge(array('save'), (array) $this->_db_opt);

        return call_user_func_array(array(&$this, $data_function), $parameters);
    }

    // The heart of the storage engine, designed for CSV data.
    protected function handle_flatfile($action, $filename) {
        switch ($action) {
            case "load":
                // Make sure we can load members.
                if (!is_readable($filename)) {
                    throw new Exception("File: $filename, is not readable");
                }
                // Open our data file and load the information.
                // Populate $this->members as an array just the way we expect it.
                $this->members = array_flip(explode(',', file_get_contents($filename)));
                break;
            case "save":
                // Make sure we can write to the file before we move forward.
                if (!is_writeable($filename)) {
                    throw new Exception("File $filename, is now writable");
                }
                // Convert our array back to a CSV string and write it to the file.
                $status = file_put_contents($filename, implode(',', array_flip($this->members)));
                // If we failed to write to the file make sure something is done before we continue.
                if (!$status) {
                    throw new Exception("Writing to file failed!");
                }
                break;
            default:
                throw new Exception("Unknown action called on data handler.");
        }
    }

    // converts email addresses to lowercase to avoid duplication.
    // should add a regex filter here to ensure that we have a valid address
    protected function _sanitize_email(&$email) {
        $email = strtolower($email);
    }

}

function show_form() {
    echo '<form method="post" action="">' . PHP_EOL
       . 'Email Address: <input type="text" name="email"> <br />' . PHP_EOL
       . '<input type="submit" value="Cancel Newsletter" name="submit">' . PHP_EOL
       . '</form>';
}

if (isset($_POST) && isset($_POST['email'])) {
    $list = new MailingList();
    $status = $list->remove_email($_POST['email']);

    switch ($status) {
        case MalingList::EMAIL_OK:
            echo "<p class='success'>Your email was successfully removed.<p>";
            break;
        case MailingList::ERR_EMAIL_INVALID:
            echo "<p class='error'>The email address provided was invalid.</p>";
        case MailingList::ERR_EMAIL_NOTFOUND:
            echo "<p class='error'>The email address provided was not registered.</p>";
        default:
            show_form();
    }
} else {
    show_form();
}

Answer 5

Is there any reason why you don't use a database?

CREATE TABLE `emails` (`address` VARCHAR(255) NOT NULL, PRIMARY KEY (`address`)) ENGINE=InnoDB
INSERT INTO `emails` VALUES ('user1@example.com')
SELECT * FROM `emails`
DELETE FROM `emails` WHERE `address`='user1@example.com'

These are just infinitely easier and more efficient than a text file...

But if you want to use a text file...

$to_delete = 'user1@example.com';
$file = array_flip(explode(",",file_get_contents("email.txt")));
unset($file[$to_delete]);
file_put_contents("email.txt",implode(",",array_flip($file));

Basically what it does it explodes by the comma, then flips the array so that the emails are keys (and their numeric positions are values, but that doesn't matter), then it removes the email you want to delete and finally reassembles the file. The bonus of this is that it will also strip out any duplicates you may have.

You can use a similar method to add email addresses, just changing the unset line to $file['user1@example.com'] = -1; (to ensure the number doesn't conflict with anything, as that would interfere with the array flipping).