Category: Common WordPress Development

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Simple way to run WP Scheduled Crons

WordPress and Cron Jobs

As we know, by default WordPress is using its own pseudo-cron logic. It just runs at background, and while visitors don’t notice it, actual cron jobs runs when they are browsing our website.

Due to performance issues some developers decide disabling this auto-run at background and use custom calling instead.

For this purpose they simple add

 define('DISABLE_WP_CRON', 'true');

to wp-config.php file and then they add real cron job to their server’s crontab. Like this

* * * * * php /var/www/html/wp-cron.php

So it solves all problems. But, not all actually. I have faced some plugin’s where scheduled tasks are using some front-end data which doesn’t exist in php-cli mode.

That’s why for those cases i use simple trick.

Hybrid Solution – Keeping WP_Cron disabled at front-end, but with one exception.

Here is my code in crontab:

#you can keep this as well * * * * * php /var/www/html/wp-cron.php
*/5 * * * * wget --delete-after -qO- https://www.SITENAME.com/?custom_cron=1

And here is my code in wp-config.php

if(empty($_GET["custom_cron"])) define('DISABLE_WP_CRON', 'true');

These 2 small codes are doing this:

  • They are keeping wp_cron disabled for all visitors. So, no any according slowing down.
  • They let wp_cron to be enabled when custom_cron GET parameter exists.
  • And each 5 minutes, crontab calls https://www.SITENAME.com/?custom_cron=1 URL and runs all tasks via wp’s own cron.
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Quick trick – running wp-cli command via Cron Job

WP-Cli via Cron Job in Crontab

Today i faced strange issue with WP-Cli command.

I have simple php script (let’s call it task.php) which runs through Crontab. All blocks of main procedure were running OK except one. That one with 

shell_exec("cd /var/www/appname;wp COMMAND_HERE");

Nothing special, just one line of simple shell command.

I run the script in SSH Console

cd /var/www/appname; php task.php

and everything works OK, included shell_exec line.

But same script behaves differently when it is called from cronjob.

After quick investigation i noticed that it was because of WP command.

In cronjob the system doesn’t recognize this command for some already known reasons for me.

That’s why i had to set full path of WP command. And it started working.

Thus, if you face such problem, just replate this

shell_exec("cd /var/www/appname;wp COMMAND_HERE");

with this

shell_exec("cd /var/www/appname; /usr/local/bin/wp COMMAND_HERE");

And it will start working OK.

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Restrict wp-admin access by IP – when you are using Cloudflare

Restricting your wp-admin access by using simple Apache’s .htaccess rules is easy, we know.

How to restrict admin access on wordpress?

Just this rule and that’s all

<Files wp-login.php>
Order Deny,Allow
Deny from all
Allow from IP1
Allow from IP2 
#and so on
</Files>

But this would not work if you are using Cloudflare. Just because Cloudflare is middle layer between your website and your website visitor, and you get request with Cloudflare’s own IP-s, not clients’ IP-s.

In order not to lose this information about visitor IP, Cloudflare sends us real visitor’s IP as $_SERVER[‘CF-Connecting-IP’] variable.

So, we just need to adjust our htaccess rule and pass $_SERVER variable there, instead of using IP addresses.

Here is simple htaccess code which works OK with Cloudflare:

SetEnvIF CF-Connecting-IP "SOMEIPHERE1" MyIP
SetEnvIF CF-Connecting-IP "SOMEIPHERE2" MyIP2
<Files wp-login.php>
Require env MyIP
Require env MyIP2
</Files>

That’s all. After saving this block to htaccess, your wp-admin would open for specified IP addresses only.

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Easy way to collect all SQL queries in WordPress – with and without SAVEQUERIES enabled

As we know WordPress has built in DB class called WPDB and all SQL queries should run via that class.

And in WordPress Debugging the only way to collect/debug executed SQL queries is activating debug constant called SAVEQUERIES.

And this constant forces WPDB to collect all SQL queries – but to display or save those queries we need to use some custom function.

Q: Where to run that function?

A: Usually it is recommended to add saving function to wp_footer hook – simply because wp_footer runs after most processes are finished. (and admin_footer for wp_admin)

But this is totally wrong! Why? Just because wp_footer runs in template side and doesn’t include some processes such as AJAX processes.

So we need to use another hook for that.

Here are 2 simple ways to catch all SQL queries of WPDB.

Continue reading “Easy way to collect all SQL queries in WordPress – with and without SAVEQUERIES enabled”
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Creating Custom Warnings and Conditions for Contact Form 7

The most Contact Form plugin for WordPress is Contact Form 7, indeed. It has very simple structure and shortcode logic. By default it offers very simple features, meanwhile there are a lot of custom addons for it.

Sometimes i need to put some unique custom rule inside Contact Form 7, without finding corresponding addon.

Here is how i do this:

Continue reading “Creating Custom Warnings and Conditions for Contact Form 7”
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How to use the plugin template file as a theme template in WordPress

If the plugin contains some UI components, we can easily use it in the theme’s UI by putting widgets, shortcodes, JS enqueued scripts etc.

But there might be some plugins which may have completely independent UI template.

What to do in such cases? The plugin may have its own template with its own CSS, JS, UI – Say active theme is built on some custom CSS framework – but your plugin should use its own UI built on Bootstrap Framework. So they can’t live together if we just enqueue the plugin’s CSS, JS and use our UI as a shortcode or widget.

The only normal ways seems to create theme template logic inside the plugin.

Fortunately, it is possible and doesn’t need additional hacks and cheats.

Let’s first create some empty template file inside the plugin’s directory, called “the_plugins_template_file.php” – Custom Template

Continue reading “How to use the plugin template file as a theme template in WordPress”
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Internal 500 error after directory renaming

Today in one client’s web hosting (it is Nexcess, but same problem can appear in another hostings using the same technology) i needed to rename WordPress home directory. (It was installed in a sub-directory)

I renamed directory, then modified .htaccess file, and then i changed siteurl and home options in wp_options table.

These simple steps above are quite enough for making WP to work in new directory. But i started getting strange errors instead.

Fatal error: require_once(): Failed opening required ‘/chroot/home/sitename/OLDNAME/wp-blog-header.php’ (include_path=’.:/opt/…/php’) in /chroot/home/sitename/OLDNAME/wp-blog-header.php on line 52

I have checked cache layers (all cache layers were turned off at that time) and configurations. Nothing wrong. Everything was provided correctly. Then i tried to print directory name before the line

require( dirname( FILE ) . ‘/wp-blog-header.php’ );

at index.php file. After saving and testing i saw that above error was solved and i started getting the same error for another file:

Fatal error: require_once(): Failed opening required ‘/chroot/home/sitename/OLDNAME/wp-load’ (include_path=’.:/opt/…/php’) …

This time wp-load.php can’t be loaded. At this time i figured out that there is some hosting based software which can’t be refresh itself after renaming directory (BTW, apache or httpd restart doesn’t help in this case) – but if you modify the file, it pings that software and that file starts to be recognized by webserver.

So there were two ways in order to solve the problem under those conditions.

  • To modify thousands of WP files one by one – which would be stupid time wasting.
  • To send some “ping” to all files. – That’s what i did. I opened SSH command line and run this command:

find -type f -exec touch {} +

This command doesn’t modify any file, it just modifies their timestamp data which is quite enough in our case.

After running this command the website started working normally under its new name.

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WordPress AMP Plugin – Use Adsense in Classic Mode

There are 2 popular AMP plugins for WordPress:

  1. Official WordPress AMP plugin: AMP
  2. 3rd party AMP plugin: AMP for WP

AMP for WP should have an option for Adsense. But official one not.

I have made small inspection and noticed that all existing adsense codes are converted to amp tags – without any issues. But there is not any Ads JS file which should render these tags.

Its documentation is not good and doesn’t provide easy to fix information about this.

First i tried to add the needed JS code (for all type of ads) and tag (for auto-ads) correspondingly with wp_head and wp_footer native hookd. But no luck.

Classic mode of AMP plugin doesn’t fire any UI hook. Because it has own small template file.

So i decided to inspect the plugin’s code and to see which hooks it has for own small template.

Continue reading “WordPress AMP Plugin – Use Adsense in Classic Mode”