How to serialize new field in Post Model

erodriguezp

Hi there,
I'm following some tutorials but I'm not able to serialize the new field created. My goal is to show this new field in each discussion of the home page.

I created the serialization class

<?php
namespace PeruGuitar\PostView\Listener;

use Flarum\Api\Event\Serializing;
use Flarum\Api\Serializer\DiscussionSerializer;

class AddPostViewsAttribute
{
    public function handle(Serializing $event)
    {
        if ($event->isSerializer(DiscussionSerializer::class)) {
            $event->attributes += [
                'views' => $event->model->views,
            ];
        }
    }
}

I updated the extends.php to include the serialization

<?php
namespace PeruGuitar\PostView;

use Flarum\Extend;

use Flarum\Api\Event\Serializing;
use PeruGuitar\PostView\Listener\AddPostViewsAttribute;

return [
    (new Extend\Frontend('forum'))
        ->js(__DIR__.'/js/dist/forum.js')
        ->css(__DIR__.'/less/forum.less'),
    (new Extend\Frontend('admin'))
        ->js(__DIR__.'/js/dist/admin.js')
        ->css(__DIR__.'/less/admin.less'),
    new Extend\Locales(__DIR__.'/locale'),
    
    (new Extend\Event)
        ->listen(Serializing::class, AddPostViewsAttribute::class),
];

And in my js component, I'm extending the object.

app.initializers.add('peruguitar/flarum-ext-post-views', () => {
  Discussion.prototype.views = Model.attribute('views');

  extend(DiscussionListItem.prototype, 'infoItems', function (items) {
    items.add('views', addPostsViewItem(0), 0);
  });
});

Please I need a litle help because the documentation is frustrating and the example that I took it is for a User but is not working in my case. https://www.sitepoint.com/writing-a-flarum-extension-building-a-custom-field/

clarkwinkelmann

erodriguezp this part of the tutorial is outdated. Flarum no longer uses events to make serializers extendable, instead a closure-based extender is provided by Flarum.

See https://docs.flarum.org/extend/api#extending-serializers

It would be something like this, directly in extend.php (untested code):

<?php
namespace PeruGuitar\PostView;

use Flarum\Extend;

use Flarum\Api\Serializer\DiscussionSerializer;
use PeruGuitar\PostView\Listener\AddPostViewsAttribute;

return [
    (new Extend\Frontend('forum'))
        ->js(__DIR__.'/js/dist/forum.js')
        ->css(__DIR__.'/less/forum.less'),
    (new Extend\Frontend('admin'))
        ->js(__DIR__.'/js/dist/admin.js')
        ->css(__DIR__.'/less/admin.less'),
    new Extend\Locales(__DIR__.'/locale'),

    (new Extend\ApiSerializer(DiscussionSerializer::class))
        ->attribute('views', function ($serializer, $discussion) {
                return $discussion->views;
        })
];

erodriguezp

clarkwinkelmann I fixed the problem, this is my solution using var_dump to understand the object structure

    (new Extend\ApiSerializer(DiscussionSerializer::class))
        ->attribute('views', function ($serializer, $model) {
            return $model->firstPost->views;
        })

In my case I want to resolve the field views from the table posts.

clarkwinkelmann

erodriguezp to make your code as robust as possible, keep in mind $discussion->firstPost might be NULL if the first post was deleted permanently manually or by an extension 😉

Also, retrieving a relationship in a serializer can lead to performance issues when many records are listed in a single API response, as each call might lead to a new SQL query. Flarum eager-loads a number of relationships on the /discussions endpoint but I'm not sure whether firstPost is part of them. I think it is since it's visible on the frontpage. Otherwise we have an eager loading extender to add additional relationships to the list.

erodriguezp

clarkwinkelmann hello bro, I was a confusion from my side, the correct table is discussions instead of post.

    (new Extend\ApiSerializer(DiscussionSerializer::class))
        ->attribute('views', function ($serializer, $model) {
            return $model->views;
        })