How to render initial posts on page load in a Gutenberg block using the Interactivity API?

Question

I have the following code (view.js) for a Gutenberg block which uses the Interactivity API that renders posts when clicking a button:

import { store, getContext, getElement } from '@wordpress/interactivity';

store('my-store', {
    callbacks: {
        renderContent() {
            const context = getContext();
            const element = getElement();
            if (context.posts !== null) {
                var html = '';
                for (var i = 0; i < context.posts.length; i++) {
                    var post = context.posts[i];
                    html += '<article id="post-' + post.id + '" class="wp-block-infinite-latest-posts__post">';
                    html += '<h2 class="wp-block-infinite-latest-posts__post-title">' + post.title.rendered + '</h2>';
                    html += '<div class="wp-block-infinite-latest-posts__post-content">' + post.content.rendered + '</div>';
                    html += '</article>';
                }
                context.offset = context.offset + context.number;
                element.ref.innerHTML += html;
            }
        },
    },
    actions: {
        *getPosts() {
            const context = getContext()
            const posts = yield fetch(
                'https://' + window.location.hostname + '/wp-json/wp/v2/posts?per_page=' + encodeURIComponent(context.number) + '&offset=' + encodeURIComponent(context.offset) + '&categories=' + encodeURIComponent(context.category)
            ).then(function (response) {
                return response.json()
            })
            context.posts = posts;
        },
    }
});

This is the render code in PHP:

<?php
    $block_attributes = get_block_wrapper_attributes()
?>
<div
    <?php echo $block_attributes; ?>
    data-wp-interactive="my-store"
    <?php
    echo wp_interactivity_data_wp_context(
        array(
            'posts'    => null,
            'number'   => $attributes['number'],
            'offset'   => 0,
            'category' => $attributes['category'],
        )
    );
    ?>
>
    <div data-wp-watch="callbacks.renderContent"></div>
    <button data-wp-on--click="actions.getPosts">Load more</button>
</div>

The code works, but the user must click the 'Load more' button to display the first n posts. How can I modify my code so that the first n posts are rendered when the page loads? Is there an Interactivity API directive for this?

Answer 1

You could consider running actions.getPosts on mount via data-wp-init like:

<div … data-wp-init="actions.getPosts">

As per the documentation:

This directive runs a callback only when the node is created.

You could also consider server-rendering the initial set of posts, like:

<div data-wp-watch="callbacks.renderContent">
  <?php
  $query = new WP_Query(
    array(
      …
    )
  );
  ?>
  <?php while( $query->have_posts() ) : ?>
    …