Fixing PHPStan Issues in Livewire Components with Larastan-Livewire

The Issue

I was recently working on some updates to Find A PR (an open-source Livewire application I created and maintain). As part of the updates, I added a computed property to one of the Livewire components, which caused PHPStan to throw an error I hadn't seen before.

If you're not familiar with computed properties in Livewire, they are methods that are decorated with the #[Livewire\Attributes\Computed] attribute. This allows you to define a method that can be accessed as if it were a property on the component. The benefit is that they can be used to compute values based on other properties or values, and the result is memoised for the duration of the request, so you can access it multiple times without recalculating it. A bonus is that you can also cache the value for future requests if you choose to.

To understand the issue I encountered, let's first look at the code that I added to the Livewire component:

        
app/Livewire/ListIssues
 1declare(strict_types=1);
 2 
 3namespace App\Livewire;
 4 
 5use Illuminate\Support\Facades\Cache;
 6use Livewire\Attributes\Computed;
 7use Livewire\Component;
 8 
 9final class ListIssues extends Component
10{
11    // ...
12 
13    #[Computed]
14    public function gitHubRateLimitExceeded(): bool
15    {
16        return Cache::has('GitHub-Rate-Limit-Exceeded');
17    }
18 
19    public function mount(): void
20    {
21        // ...
22 
23        if (! $this->gitHubRateLimitExceeded) {
24            // ...
25        }
26 
27        // ...
28    }
29 
30    // ...
31}    

In the code example above, we can see that I've got a gitHubRateLimitExceeded method that is decorated with the #[Computed] attribute. This allows me to access it as if it were a property on the component, like so: $this->gitHubRateLimitExceeded.

Although this is completely valid code that runs without issue, the problem is that there isn't actually a gitHubRateLimitExceeded property on the component. Instead, it's accessed using magic methods by Livewire under the hood. So when I ran PHPStan after making these changes, it returned an error:

        
 1------ ---------------------------------------------------------------------------------------
 2  Line   Livewire/ListIssues.php
 3 ------ ---------------------------------------------------------------------------------------
 4  106    Access to an undefined property App\Livewire\ListIssues::$gitHubRateLimitExceeded.
 5         🪪  property.notFound
 6         💡  Learn more: https://phpstan.org/blog/solving-phpstan-access-to-undefined-property
 7         at app/Livewire/ListIssues.php:106
 8 ------ ---------------------------------------------------------------------------------------
 9
10
11
12 [ERROR] Found 1 error    

The Fix

After a quick search online, I found a package created by Caleb White called calebdw/larastan-livewire that adds support for Livewire components to Larastan. You can check out the repo at: https://github.com/calebdw/larastan-livewire.

The main issue that this package solves is that it allows PHPStan to recognise computed properties on Livewire components.

I've seen Caleb around online quite a bit, and he's always come across as a knowledgeable, helpful developer, so I trusted this package would be a good solution. It helped that the package is still maintained and has 880k downloads (at the time of writing this article). So I decided to give it a try.

I installed the calebdw/larastan-livewire package via Composer by running the following command:

        
1composer require calebdw/larastan-livewire --dev    

I then registered the package in my phpstan.neon by adding the following:

        
phpstan.neon
1includes:
2    - ./vendor/calebdw/larastan-livewire/extension.neon    

This resulted in my phpstan.neon looking like so:

        
phpstan.neon
 1includes:
 2    - ./vendor/larastan/larastan/extension.neon
 3    - ./vendor/calebdw/larastan-livewire/extension.neon
 4
 5parameters:
 6
 7    paths:
 8        - app
 9
10    level: 5
11
12    ignoreErrors:
13
14    excludePaths:    

I then ran PHPStan again (using ./vendor/bin/phpstan) and the error was gone. Whoop whoop! Thanks to the package, PHPStan now recognises computed properties on Livewire components, so calling $this->gitHubRateLimitExceeded no longer throws an error.

I was really happy with this solution, and it was a relief not to have to start tinkering to get it working. I was able to just fix the issue and move on to my next task.

Thanks again, Caleb, for building an awesome package and sharing it with the community!

Alternative Fix

Before discovering the calebdw/larastan-livewire package, the first fix I considered was adding a @property-read annotation to the class docblock, like so:

        
app/Livewire/ListIssues
 1declare(strict_types=1);
 2 
 3namespace App\Livewire;
 4 
 5use Illuminate\Support\Facades\Cache;
 6use Livewire\Attributes\Computed;
 7use Livewire\Component;
 8 
 9/**
10 * @property-read bool $gitHubRateLimitExceeded
11 */
12final class ListIssues extends Component
13{
14    // ...
15 
16    #[Computed]
17    public function gitHubRateLimitExceeded(): bool
18    {
19        return Cache::has('GitHub-Rate-Limit-Exceeded');
20    }
21 
22    public function mount(): void
23    {
24        // ...
25 
26        if (! $this->gitHubRateLimitExceeded) {
27            // ...
28        }
29 
30        // ...
31    }
32 
33    // ...
34}    

Doing this would fix the PHPStan issue. However, I avoid docblock annotations where possible, as they can be incorrect or become outdated.

For example, if we were to remove the gitHubRateLimitExceeded method, change its return type, or rename it, we would also need to remember to update the docblock annotation. If we forget, it could confuse other developers working on the project. It's one of the reasons I also like to use data transfers objects (DTOs) and similar structures in my code because they allow me to define the structure of data in the code itself, rather than relying on docblocks.

Conclusion

Hopefully, this article has given you a quick insight into the calebdw/larastan-livewire package and how it might help you fix PHPStan issues in your Livewire components.

If you enjoyed reading this post, I'd love to hear about it. Likewise, if you have feedback to help me improve future posts, I'd love to hear it.

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