Welcome to the NZRT Wiki Podcast. Today we’re looking at Hooks & Filters.

If you’ve spent any time working with WordPress, you’ve probably heard the word “hooks” thrown around. But what exactly are they, and why do they matter? Let’s break it down in a way that actually makes sense.

At its core, WordPress hooks are a system that lets you — as a plugin or theme developer — step into WordPress at specific moments and either do something extra, or change something that’s already happening. The key idea is that you never have to touch the WordPress core files themselves. Instead, WordPress gives you these designated spots where you can attach your own code, and it handles the rest.

There are two types of hooks you need to know about: actions and filters. They sound similar but they do different things.

Let’s start with actions. An action hook is about doing something at a specific event. Think of it like an alarm going off — when WordPress reaches a certain point in its process, it fires that alarm, and any code you’ve attached to it wakes up and runs.

Here’s a simple example to picture. Say you want to add some custom text to the footer of every page on your site. You’d tell WordPress: “Hey, when you get to the footer moment, run my function.” The code example in the docs shows exactly that — you register a function called something like “my custom footer,” attach it to the footer event, and whenever WordPress builds that part of the page, it calls your function and outputs a paragraph of custom footer text. You didn’t touch a single core file. WordPress just calls your code at the right moment.

Now let’s talk about filters. Filters are a little different. Instead of just doing something, they’re about modifying data before it gets used or displayed. WordPress passes a piece of content to your function, you change it, and you hand it back.

Picture the post content on a blog. WordPress grabs your post text from the database, and before it shows it on screen, it runs it through a series of filters. The example in the docs shows a filter hooked into the content pipeline — your function receives the raw content, wraps it inside a div element, and returns that wrapped version. WordPress then uses that modified version for display. You’ve changed the output without ever touching how WordPress stores or retrieves it. Clean and surgical.

Now here’s where it gets a bit more nuanced — hook priority. When multiple functions are attached to the same hook, WordPress needs to know what order to run them in. That’s where priority comes in. Every hook has a default priority of ten. Lower numbers run earlier, higher numbers run later.

So if you have two filters both attached to the post title hook, and one has a priority of five while the other has a priority of fifteen, the one set to five runs first. It gets to modify the title before the second function even sees it. This matters a lot when the output of one function is meant to feed into another. Getting the order wrong can produce unexpected results, so it’s worth being deliberate about priority when you’re stacking multiple hooks.

Now let’s bring this back to NZRT specifically. If you’re working on anything inside the WP-Script plugin, you’ll see hooks used heavily to integrate Dolibarr REST API calls directly into the WordPress request cycle. Rather than building bespoke page loads or custom endpoints from scratch every time, hooks let the plugin slot into exactly the right moment in WordPress’s flow to make those API calls happen transparently.

SmartSlider 3 Pro, which you might be working with for visual content, also hooks into the theme templates — meaning it can inject slider content at template-level hook points without requiring manual template edits.

And if you’ve been involved in the agent role-based content filtering work, that’s another place hooks shine. Custom hooks allow content to be shown or hidden based on a user’s role, all handled through filter logic rather than conditional spaghetti scattered through templates.

So to pull it all together: actions let you run code at events, filters let you modify data in transit, priority controls the order everything fires in, and NZRT uses all of this to keep WordPress integrations modular and maintainable. If you want to dig deeper, the related topics to check out are Plugin Development, the WordPress REST API, and the WP-Script Core documentation.

That’s it for this episode of the NZRT Wiki Podcast. Thanks for listening.