How to resolve the “undefined variable” notce when I put a flag on a Views page?

Question

I want to place a flag link on a page, as suggested on that page: https://www.drupal.org/node/295383

The flag will subscribe the user to the most recent content page, which is done in Views.

I have the Flags: subscribe (by current user) Relationship.

I have installed Views PHP and I want to add to the header of the view a Global:PHP with the code <?php print flag_create_link('subscribe', $node->nid); ?>

Unfortunately I receive an error:

Notice: Undefined variable: node in __lambda_func() (line 1 of .../sites/all/modules/views_php/plugins/views/views_php_handler_area.inc(39) : runtime-created function). Notice: Trying to get property of non-object in __lambda_func() (line 1 of .../sites/all/modules/views_php/plugins/views/views_php_handler_area.inc(39) : runtime-created function).

What could be the reason for that?

Any help appreciated.

Answer 1

As I understand it, OOB it won't work because Flags require an entity to function, but Views pages are simple menu callbacks, not actual entities (such as nodes, users, comments, etc). So, in order to do this, you would need to trick it into think it is an entity:

• create a content type, Dummy Page for this example

• remove the body and restrict editing, deleting, etc to admin only

• Create a node with this content, using the title you want for the View, Recent Content for this example, give it a path alias /recent

• create the view as a block, and in the block UI, set it to show only on the recent page

• Create a flag for Nodes, Favourites

• create a page--recent.tpl.php file and override the $action_link for the page (or modify it drastically however you want), but include:

<?php print flag_create_link('favourites', $node->nid); ?>

Or use the built in flag link that comes with the Flag

• then do whatever you were going to do originally with the flag. You can include it in other Views pages by creating new nodes of that content type and include the View as a block, etc.

This will trick the Flag into thinking the page is an entity and track it properly, as well as display it on the page wherever you decide to put it

Answer 2

The error arises because there is no $node variable defined in the scope. Try looking inside the $results variable; something like this should work:

<?php print flag_create_link('subscribe', $results[0]->nid); ?>

This will print a subscribe link for the first row of the view. Also, you have to ensure that the nid is present in your result object. It should be already there, but if not, add the "Content: Nid" field and hide it by checking the "Exclude from display" option.