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44.

Using the autocomplete-controller

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Now that we have a new autocomplete controller registered, let's try to use it instead of our custom search-preview controller to power the search preview functionality.

Setting up the Controller in HTML

To see how, go back to the docs. Hmm... looking at this example, we need to add the data-controller attribute to an element that's around both the input that we type into and the div where the results will go. We also need to pass a url value set to where the Ajax call should be made. The input needs a target called input... and the results go into a target called results. We don't need to worry about this hidden element: that's only needed if you're building a form and want to update a form field when the user selects an option.

Open the template for the homepage: templates/product/index.html.twig. First, change the name of the controller from search-preview to autocomplete. Then... nice! We were already passing a value called url, so that's done.

111 lines | templates/product/index.html.twig
// ... lines 1 - 2
{% block body %}
// ... lines 4 - 37
<form>
<div
// ... line 40
{{ stimulus_controller('autocomplete', {
// ... line 42
}) }}
>
// ... lines 45 - 57
</div>
</form>
// ... lines 60 - 109
{% endblock %}

Next, on the input, we don't need the "action" anymore: the controller will handle setting that up for us. But we do need to identity this as the text input by adding a target: data-autocomplete-target="input".

111 lines | templates/product/index.html.twig
// ... lines 1 - 2
{% block body %}
// ... lines 4 - 37
<form>
// ... lines 39 - 44
<input
// ... lines 46 - 50
data-autocomplete-target="input"
>
// ... lines 53 - 58
</form>
// ... lines 60 - 109
{% endblock %}

Finally, update the "results" target to use the new controller name - autocomplete - and the target name is now results with an "S".

111 lines | templates/product/index.html.twig
// ... lines 1 - 2
{% block body %}
// ... lines 4 - 37
<form>
// ... lines 39 - 53
<div
// ... line 55
data-autocomplete-target="results"
></div>
// ... line 58
</form>
// ... lines 60 - 109
{% endblock %}

Done. Let's try it! Move over, find our site, refresh, type "di" and... nothing happened! Well, not nothing. I can see that there was an Ajax call. In fact, two Ajax calls: I can see that down in the web debug toolbar.

Let's check out one of these in our Network tool. Look at the "Preview". Whoa! It's a little small... but this is the full HTML page. Let's make this bigger. Yep, this didn't render just the results partial, it returned the full page!

What happened?

How the autocomplete Ajax Works

Okay. I noticed a few things. To start, by complete chance, the autocomplete controller sends the contents of our input as a query parameter called q... which is exactly what we were using before! You can see that in src/Controller/ProductController.php: we read q as our search term. Awesome!

60 lines | src/Controller/ProductController.php
// ... lines 1 - 14
class ProductController extends AbstractController
{
// ... lines 17 - 20
public function index(Request $request, CategoryRepository $categoryRepository, ProductRepository $productRepository, Category $category = null): Response
{
$searchTerm = $request->query->get('q');
// ... lines 24 - 40
}
// ... lines 42 - 58
}

But we also look for a ?preview query parameter to know if we should render a page partial.

60 lines | src/Controller/ProductController.php
// ... lines 1 - 20
public function index(Request $request, CategoryRepository $categoryRepository, ProductRepository $productRepository, Category $category = null): Response
{
// ... lines 23 - 28
if ($request->query->get('preview')) {
return $this->render('product/_searchPreview.html.twig', [
// ... line 31
]);
}
// ... lines 34 - 40
}
// ... lines 42 - 60

Previously, in search-preview controller, we added that query parameter manually in JavaScript. We can't do that now... but that's ok! We can add it to the url value.

In index.html.twig, back up on the url, add a second argument to path and pass preview: 1. That will fix the full page problem.

111 lines | templates/product/index.html.twig
// ... lines 1 - 2
{% block body %}
// ... lines 4 - 37
<form>
<div
// ... line 40
{{ stimulus_controller('autocomplete', {
url: path('app_homepage', { preview: 1 })
}) }}
>
// ... lines 45 - 57
</div>
</form>
// ... lines 60 - 109
{% endblock %}

But if you try it now... the same thing happened again! An Ajax call was made... but no results are showing up! On the network tab... yeah! It is now returning the partial, not the full page. So... why don't we actually see the results below the input?

Adding the role="option" Attribute

Because... the other rule of this library - which I totally would have noticed if I had read the documentation a bit more carefully (sorry!) - is that each result must be identified by a role="option" attribute. But we don't need this data-autocomplete-value attribute: that controls the value that would go into the hidden input... which we don't need. But we definitely need the role="option" thing.

Let's go add it! The template for the partial lives at templates/product/_searchPreview.html.twig. On the <a> tag, which represents a single option, add role="option".

24 lines | templates/product/_searchPreview.html.twig
<div class="list-group">
{% for product in products %}
<a
role="option"
// ... lines 5 - 6
>
// ... lines 8 - 18
</a>
// ... lines 20 - 21
{% endfor %}
</div>

Oh, and down here on the "no results", we need to do the same thing: role="option". And if you look again at the documentation, to have an option but make it not selectable, you can add aria-disabled="true". That will make it show up on the list... but I won't be able to select it.

24 lines | templates/product/_searchPreview.html.twig
// ... line 1
{% for product in products %}
// ... lines 3 - 19
{% else %}
<div class="list-group-item" role="option" aria-disabled="true">No results found!</div>
{% endfor %}
// ... lines 23 - 24

This time, back on the site, we don't even need to refresh the page: I can type and boom! There it is! It looks exactly like before! And as a bonus, the controller has a feature that ours never did: the ability to hit up and down on our keyboard to go through the results. And, pressing enter, activates that item.

Oh, and by the way! Technically, we did not need to make our controller for the Ajax call return a partial. If we returned the whole page from the Ajax call... it would still work exactly like it does now... because the autocomplete controller looks for the role="option" attribute and only renders those. Rendering just the partial is a bit faster... but it's technically not needed... which is kind of amazing!

Let's celebrate by deleting our old search-preview controller. Thanks for teaching us how to use Stimulus! But now it's time for us move forward with less custom code.

Making third-Party Controllers Lazy

I have one more wish... or question: could we make this autocomplete controller load lazily? Earlier we made the whole chart-js controller "lazy" in controllers.json by setting fetch: 'lazy'. We also made our own submit-confirm_controller lazy by adding this special comment above the class.

But what about a third-party controller? We don't register this in controllers.json and... we can't exactly open up the file and add a comment in it. So, can we make it lazy?

We can! Though, due to some rigidness in how Webpack works, the syntax... isn't amazing. In bootstrap.js, we need to change the import to pass through the special @symfony/stimulus-bridge/lazy-controller-loader. You can do that by literally saying import { Autocomplete } from... - the name of that loader - an exclamation point, and then the name of the module that you want to import.

So, this module will now be passed through the loader. That... by itself, won't change anything. But now, before the exclamation point, add ?lazy=true.

The lazy-controller-loader is what looks for the stimulusFetch comment above the controller. Since that won't be there, this ?lazy=true is our way to force laziness.

And, normally, this would be all we need! It's a bit ugly, but not too bad! And we get the laziness we want.

However, notice that the stimulus-autocomplete module uses a named export instead of a default export. What I mean is, when we use this, we have to say import { Autocomplete } - that's a named export - instead of just being able to say import Autocomplete. If we tried this, it would not work.

Anyways, since the library uses a named export, we need to notify the loader about this so it knows where to find the code. We do that by adding one more loader option: &export=Autocomplete: the name of the import.

13 lines | assets/bootstrap.js
// ... line 1
import { Autocomplete } from '@symfony/stimulus-bridge/lazy-controller-loader?lazy=true&export=Autocomplete!stimulus-autocomplete';
// ... lines 3 - 13

Ok, now we're done. It's ugly, but it gets the job done if you need a 3rd party controller to load lazily.

Let's see it in action. Move over, refresh the page... and go down to your Network tools filtered for JavaScript. Yes! Look at this long name: this is the file that contains stimulus-autocomplete. The "Initiator" proves that it's being downloaded lazily, only after the data-controller="autocomplete" was found on the page.

If we go to any other page... that code is never downloaded.

The new stimulus-autocomplete controller allows us to have less custom code and better functionality, with the ability to press up and down on the search results. But we did lose one thing: the nice CSS transitions! Can we somehow add those to this third-party controller? As long as the controller dispatches the right events, we totally can. Let's learn how next