Update the subscriptions upon submit

[leofeyer]

Right now, the newsletter bundle tries to update the member subscriptions in the onload_callback:

newsletter-bundle/src/Resources/contao/dca/tl_member.php

Line 15 in f8301a9

$GLOBALS['TL_DCA']['tl_member']['config']['onload_callback'][] = array('Newsletter', 'updateAccount');

However, this will cause an integrity constraint violation if an e-mail address exists already:

Integrity constraint violation: 1062 Duplicate entry '1-d.evans@example.com' for key 'pid_email'

How to reproduce

1. Allow members to subscribe to channels.
2. Subscribe Donna Evans (d.evans@example.com) to a channel.
3. Subscribe John Smith (j.smith@example.com) to the same channel.
4. Try to change John's e-mail to d.evans@example.com.

The onload_callback is executed before the user input is validated and stored (tl_member.email has the 'unique' => true flag set). However, it should be executed upon submit instead, so Contao shows the "duplicate entry in field e-mail" error message and only updates the subscriptions after validating the user input.

@contao/developers Is this a bug or a feature?

[leofeyer]

Here is a quick fix that does not require using a different hook:

--- a/src/Resources/contao/classes/Newsletter.php
+++ b/src/Resources/contao/classes/Newsletter.php
@@ -802,8 +802,20 @@ class Newsletter extends \Backend
 				// E-mail address has changed
 				if (!empty($_POST) && $strEmail != '' && $strEmail != $objUser->email)
 				{
-					$this->Database->prepare("UPDATE tl_newsletter_recipients SET email=? WHERE email=?")
-								   ->execute($strEmail, $objUser->email);
+					$objCount = $this->Database->prepare("SELECT COUNT(*) AS count FROM tl_newsletter_recipients WHERE email=?")
+											   ->execute($strEmail);
+
+					// Delete the old subscription if the new e-mail address exists (see #19)
+					if ($objCount->count > 0)
+					{
+						$this->Database->prepare("DELETE FROM tl_newsletter_recipients WHERE email=?")
+									   ->execute($objUser->email);
+					}
+					else
+					{
+						$this->Database->prepare("UPDATE tl_newsletter_recipients SET email=? WHERE email=?")
+									   ->execute($strEmail, $objUser->email);
+					}
 
 					$objUser->email = $strEmail;
 				}

[leofeyer]

I guess ebcd6c7 is enough for the time being.