REST API - Head Tags Plugin error with NewsPaper theme

mosamlife · 21 April 2020 14:54

REST API - Head Tags Plugin Not working I got this error while I am hitting rest API endpoint.

https://www.example.com/wp-json/wp/v2/posts/

Pablo · 21 April 2020 15:37

I’m sorry for the inconvenience. What version of WordPress do you have? Have you tried to deactivate your other plugins to see if there’s a conflict? Do you have access to your error logs?

We are going to take a look, but still, we need a little more info to be able to reproduce the error.

mosamlife · 22 April 2020 08:20

Current WordPress version 5.4
I also tried with deactivating all the plugin still got the same error. but when I am hitting the endpoint 4 to 5 times it’s working. but with frontity connect it is throwing 500 error.

Pablo · 22 April 2020 17:37

Thanks @mosamlife

Do you have access to the server error logs?

mmczaplinski · 22 April 2020 17:42

Hi @mosamlife!

Since you mention this, it seems to be the error on the server-side. To expand on what @Pablo has mentioned, if you can paste the log from the server that would help us troubleshoot it.

Is there any more helpful information in the client-side error in the browser console?

mosamlife · 23 April 2020 11:32

Hello @Pablo @mmczaplinski Thanks for quick reply. I found the solution It was my current theme that causing the issue with rest api head tags plugin. Current theme : NewsPaper

luisherranz · 23 April 2020 11:44

May we know what was it? Is it something we could solve?

mosamlife · 23 April 2020 11:50

yes you check the error here

luisherranz · 23 April 2020 15:01

Could you please check if you have the latest version of the Head Tags plugin?

mosamlife · 23 April 2020 15:50

I am already using the latest version

luisherranz · 26 April 2020 09:02

Ok, thanks @mosamlife. I guess the affected hook is wp_head then. Can we download the theme from somewhere to check it out?

mosamlife · 27 April 2020 07:47

Sure! I will send you in DM

David · 28 April 2020 15:17

Hi @mosamlife!

I did some tests with the theme you shared in DM and I was able to reproduce the problem. It looks like the NewsPaper theme is not compatible with the Head Tags plugin for some reasons:

The REST API - Head Tags plugin runs the wp_head hook for each post, page, etc. in order to render their tags. This means that for the same REST API request the wp_head hook has to run several times, one for each entity. The thing is that the NewsPaper theme is registering an action called td_js_generator to the wp_head hook that throws an error when it’s executed more than once. That’s the error you see.
```
Fatal error: Uncaught ErrorException:
  td_js_buffer::add_to_header
  - the header JS was already rendered when you called td_js_buffer::add_to_header() 
```

Apart from that, the NewsPaper theme is using a header.php template that renders the title outside of the wp_head hook, making that tag unable to be processed by the Head Tags plugin, and therefore not showing that tag in the REST API response.

<!-- header.php -->
<head>
    <meta charset="<?php bloginfo( 'charset' );?>" />
    <!-- The title is rendered here -->
    <title><?php wp_title('|', true, 'right'); ?></title>
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="pingback" href="<?php bloginfo( 'pingback_url' ); ?>" />
    <!-- The theme is calling `wp_head` here -->
    <?php wp_head(); ?>
</head>

Having said that, you can add the following code as a workaround in the functions.php of your theme that would remove the action that throws the error and add the title only when a REST API request is made. I think it’s safe to remove the td_js_generator action as it only adds JavaScript code that the Head Tags plugin won’t return anyways.

add_action('rest_api_init', function() {
    // Remove the failing hook.
    remove_action('wp_head', 'td_js_generator', 10);
    // Add a new hook for the <title> tag.
    add_action('wp_head', function () {
        echo '<title>' . wp_title('|', false, 'right') . '</title>';
    });
});

I hope this workaround works for you. Cheers!

mosamlife · 28 April 2020 15:38

@David Thanks for the detailed investigation. I already applied my temporary fix for the same but your solution is pretty much straightforward

Thanks

luisherranz · 29 April 2020 15:01

Hey @David, would it make sense to create a list of disabled hooks in our plugin and add this one remove_action('wp_head', 'td_js_generator', 10); to the list?

I know this is going to be hard to maintain but at least we can add problematic hooks when a problem arises.

David · 4 May 2020 16:05

I think it would be better to let people know why those plugins are failing and how to make it work. Maybe with a “troubleshooting” section in the plugin docs or something like that.

What do you think?

mosamlife · 4 May 2020 17:32

+1 for this @David

luisherranz · 25 May 2020 11:55

Sorry for the delay guys. If you think a troubleshooting section is better then it’s fine. Let’s add it.

@David can you take care of it?

David · 25 May 2020 14:28

Sure! I’ll link it here once it’s done.

David · 22 June 2020 19:18

Hey, we published the Troubleshooting section in the docs some time ago and I forgot to share the link here!

Check it out

https://docs.frontity.org/frontity-plugins/rest-api-head-tags#troubleshooting