fix(content-distribution): handling multiple post meta (#199)

includes/content-distribution/class-incoming-post.php

@@ -272,7 +272,7 @@ public function is_linked(): bool {
 	 *
 	 * @return void
 	 */
-	protected function update_post_meta() {
+	protected function update_meta() {
 		$data = $this->payload['post_data']['post_meta'];
 
 		$reserved_keys = Content_Distribution::get_reserved_post_meta_keys();
@@ -297,8 +297,12 @@ protected function update_post_meta() {
 				if ( 1 === count( $meta_value ) ) {
 					update_post_meta( $this->ID, $meta_key, $meta_value[0] );
 				} else {
-					foreach ( $meta_value as $value ) {
-						add_post_meta( $this->ID, $meta_key, $value );
+					$value = get_post_meta( $this->ID, $meta_key, false );
+					if ( $value !== $meta_value ) {
+						delete_post_meta( $this->ID, $meta_key );
+						foreach ( $meta_value as $item ) {
+							add_post_meta( $this->ID, $meta_key, $item );
+						}
 					}
 				}
 			}
@@ -497,7 +501,7 @@ public function insert( $payload = [] ) {
 			$this->post = get_post( $this->ID );
 
 			// Handle post meta.
-			$this->update_post_meta();
+			$this->update_meta();
 
 			// Handle thumbnail.
 			$thumbnail_url = $post_data['thumbnail_url'];

tests/unit-tests/content-distribution/test-incoming-post.php

@@ -310,6 +310,23 @@ public function test_post_meta_sync() {
 		$this->assertEmpty( get_post_meta( $post_id, 'custom', true ) );
 	}
 
+	/**
+	 * Test adding and deleting post meta.
+	 */
+	public function test_add_and_delete_multiple_post_meta() {
+		$post_id = $this->incoming_post->insert();
+
+		$payload = $this->get_sample_payload();
+
+		$payload['post_data']['post_meta']['multiple'] = [ 'value 2', 'value 3' ];
+		$this->incoming_post->insert( $payload );
+		$this->assertSame( [ 'value 2', 'value 3' ], get_post_meta( $post_id, 'multiple' ) );
+
+		$payload['post_data']['post_meta']['multiple'] = [ 'value 3', 'value 3' ];
+		$this->incoming_post->insert( $payload );
+		$this->assertSame( [ 'value 3', 'value 3' ], get_post_meta( $post_id, 'multiple' ) );
+	}
+
 	/**
 	 * Test status changes.
 	 */