Demo of concurrency control issue

.wp-env.json

@@ -1,6 +1,6 @@
 {
 	"core": "WordPress/WordPress",
-	"plugins": [ "." ],
+	"plugins": [ ".", "./test-plugins/core-data" ],
 	"env": {
 		"tests": {
 			"mappings": {

test-plugins/core-data/bin/import_candidates.php

@@ -0,0 +1,36 @@
+<?php
+/**
+ * Imports fixture data into WordPress database
+ *
+ * @package pistachio
+ */
+
+/**
+ * Attempt to load WordPress.
+ */
+require '../../../wp-load.php';
+
+if ( ! function_exists( 'wp' ) ) {
+	die( 'Nope' );
+}
+
+/**
+ * Import candidates from candidates.json.
+ *
+ * To regenerate candidates.json, use `node bin/greenhouse-fixtures > candidates.json`
+ */
+function import_fixtures() {
+	$json = json_decode( file_get_contents( 'candidates.json' ) );
+	foreach ( $json as $c ) {
+		$post_id = wp_insert_post(
+			[
+				'post_title'  => $c->name,
+				'post_type'   => 'candidate',
+				'post_status' => 'publish',
+			]
+		);
+		$result  = update_post_meta( $post_id, 'json', $c );
+	}
+}
+
+import_fixtures();

test-plugins/core-data/coredata.php

@@ -0,0 +1,192 @@
+<?php
+/**
+ * Plugin Name: Reproduce Core Data Issue
+ * Description: A test plugin to demonstrate issues with @wordpress/core-data
+ */
+
+function core_data_issue() {
+	?>
+	<div id="container">
+		<h1>Reproduce Issue with @wordpress/core-data</h1>
+		<div id="core-data"></div>
+	</div>
+	<?php
+}
+
+/**
+ * Add a menu for the main view, and a submenu item for the Candidates Custom Post Type.
+ */
+function coredata_issue() {
+	add_menu_page(
+		'Core data issue',
+		'Core data issue',
+		'edit_posts',
+		'coredata_issue',
+		'core_data_issue'
+	);
+}
+add_action( 'admin_menu', 'coredata_issue' );
+
+/**
+ * Enqueue our scripts and styles.
+ */
+function enqueue_scripts() {
+	$dependencies_file = plugin_dir_path( __FILE__ ) . '/dist/index.asset.php';
+	$script_dependencies = array( 'wp-polyfill' );
+	if ( file_exists( $dependencies_file ) ) {
+		$asset_manifest      = include $dependencies_file;
+		$script_dependencies = $asset_manifest['dependencies'];
+	}
+
+	wp_enqueue_script( 'core_data', plugin_dir_url( __FILE__ ) . 'dist/index.js', $script_dependencies );
+	wp_enqueue_style( 'core_data', plugin_dir_url( __FILE__ ) . 'style.css' );
+}
+add_action( 'admin_enqueue_scripts', 'enqueue_scripts', 10 );
+
+/**
+ * Register the Book Custom Post Type.
+ */
+function book_post_type() {
+
+	$labels = array(
+		'name'           => _x( 'Books', 'Post Type General Name', 'coredata_issue' ),
+		'singular_name'  => _x( 'Book', 'Post Type Singular Name', 'coredata_issue' ),
+		'menu_name'      => __( 'My Books', 'coredata_issue' ),
+		'name_admin_bar' => __( 'Books', 'coredata_issue' ),
+		'archives'       => __( 'Book Archives', 'coredata_issue' ),
+		'attributes'     => __( 'Book Attributes', 'coredata_issue' ),
+		'all_items'      => __( 'All books', 'coredata_issue' ),
+		'add_new'        => __( 'Add New', 'coreddata_issue' ),
+	);
+	$args   = array(
+		'label'               => __( 'Book', 'coredata_issue' ),
+		'description'         => __( 'Book', 'coredata_issue' ),
+		'labels'              => $labels,
+		'supports'            => array( 'title' ),
+		'hierarchical'        => false,
+		'public'              => true,
+		'publicly_queryable'  => true,
+		'show_ui'             => true,
+		'show_in_menu'        => false,
+		'menu_position'       => 5,
+		'exclude_from_search' => false,
+		'searchable'          => true,
+		'publicly_queryable'  => true,
+		'rewrite'             => false,
+		'capability_type'     => 'post',
+		'show_in_rest'        => true,
+		'rest_base'           => 'books',
+	);
+	register_post_type( 'book', $args );
+
+	register_rest_field(
+		'book',
+		'json',
+		[
+			'get_callback'    =>
+			function( $object = '', $field_name = '', $request = array() ) {
+				return get_post_meta( $object['id'], $field_name, true );
+			},
+			'update_callback' =>
+			function( $value, $object, $field_name ) {
+				return update_post_meta( $object->ID, $field_name, $value );
+			},
+		]
+	);
+
+}
+add_action( 'init', 'book_post_type' );
+
+/**
+ * Increase REST API per page value.
+ *
+ * @param array $params Default API paramaters.
+ *
+ * @return array Filtered API parameters.
+ */
+function change_per_page( $params ) {
+	if ( isset( $params['per_page'] ) ) {
+		$params['per_page']['maximum'] = 9999;
+	}
+	return $params;
+}
+add_filter( 'rest_candidate_collection_params', 'change_per_page', 10, 1 );
+
+/**
+ * Import books from books json.
+ */
+function import_fixtures() {
+	if (get_option( 'fixtures_imported', '0' ) == '1') {
+		return;
+	}
+
+	// Dummy data
+	$books = <<<JSON
+[
+	{
+		"title": "In Search of Lost Time",
+		"isFavouriteBook": false
+	},
+	{
+		"title": "Ulysses",
+		"isFavouriteBook": false
+	},
+	{
+		"title": "Don Quixote",
+		"isFavouriteBook": false
+	},
+	{
+		"title": "The Great Gatsby",
+		"isFavouriteBook": false
+	},
+	{
+		"title": "Book5",
+		"isFavouriteBook": false
+	},
+	{
+		"title": "Book6",
+		"isFavouriteBook": false
+	},
+	{
+		"title": "Book7",
+		"isFavouriteBook": false
+	},
+	{
+		"title": "Book8",
+		"isFavouriteBook": false
+	},
+	{
+		"title": "Book9",
+		"isFavouriteBook": false
+	},
+	{
+		"title": "Book10",
+		"isFavouriteBook": false
+	},
+	{
+		"title": "Book11",
+		"isFavouriteBook": false
+	}
+]
+JSON;
+
+	$json = json_decode($books);
+	foreach ( $json as $c ) {
+		$post_id = wp_insert_post(
+			[
+				'post_title'  => $c->title,
+				'post_type'   => 'book',
+				'post_status' => 'publish',
+			]
+		);
+		$result  = update_post_meta( $post_id, 'json', $c );
+	}
+
+	update_option('fixtures_imported', '1');
+}
+
+add_action('init', 'import_fixtures');
+
+
+
+

test-plugins/core-data/dist/index.asset.php

@@ -0,0 +1 @@
+<?php return array('dependencies' => array('react', 'react-dom', 'wp-compose', 'wp-core-data', 'wp-data', 'wp-element', 'wp-polyfill'), 'version' => '9b01332448920e42e2c7a0a84e41d205');