Add array access semantics to ActivityPubObjects

src/Entities/ActivityPubObject.php

@@ -1,6 +1,8 @@
 <?php
 namespace ActivityPub\Entities;
 
+use ArrayAccess;
+use BadMethodCallException;
 use DateTime;
 use ActivityPub\Utils\Util;
 use Doctrine\Common\Collections\ArrayCollection;
@@ -9,7 +11,7 @@ use Doctrine\Common\Collections\ArrayCollection;
  * Represents an ActivityPub JSON-LD object
  * @Entity @Table(name="objects")
  */
-class ActivityPubObject
+class ActivityPubObject implements ArrayAccess
 {
     /**
      * @var int
@@ -162,6 +164,25 @@ class ActivityPubObject
         return false;
     }
 
+    /**
+     * Returns the value of the field with key $name
+     *
+     * The value is either a string, another ActivityPubObject, or null
+     *   if no such key exists.
+     *
+     * @return string|ActivityPubObject|null The field's value, or null if
+     *   the field is not found
+     */
+    public function getFieldValue( string $name )
+    {
+        foreach( $this->getFields() as $field ) {
+            if ( $field->getName() === $name ) {
+                return $field->getValueOrTargetObject();
+            }
+        }
+        return null;
+    }
+
     /**
      * Adds a new field on the object
      *
@@ -232,5 +253,29 @@ class ActivityPubObject
     {
         $this->lastUpdated = $lastUpdated;
     }
+
+    public function offsetExists( $offset )
+    {
+        return $this->hasField( $offset );
+    }
+
+    public function offsetGet( $offset )
+    {
+        return $this->getFieldValue( $offset );
+    }
+
+    public function offsetSet( $offset, $value )
+    {
+        throw new BadMethodCallException(
+            'ActivityPubObject fields cannot be directly set'
+        );
+    }
+
+    public function offsetUnset( $offset )
+    {
+        throw new BadMethodCallException(
+            'ActivityPubObject fields cannot be directly unset'
+        );
+    }
 }
 ?>

test/ObjectsServiceTest.php

@@ -2,6 +2,7 @@
 namespace ActivityPub\Test;
 
 use DateTime;
+use BadMethodCallException;
 use ActivityPub\Test\Config\SQLiteTestCase;
 use ActivityPub\Test\Config\ArrayDataSet;
 use ActivityPub\Entities\ActivityPubObject;
@@ -1094,5 +1095,44 @@ class ObjectsServiceTest extends SQLiteTestCase
         $this->assertTablesEqual( $expectedObjectsTable, $objectsQueryTable );
         $this->assertTablesEqual( $expectedFieldsTable, $fieldsQueryTable );
     }
+
+    public function testObjectArrayAccess()
+    {
+        $fields = array(
+            'id' => 'https://example.com/notes/1',
+            'type' => 'Note',
+            'content' => 'This is a note',
+        );
+        $now = $this->getTime( 'create' );
+        $object = $this->objectsService->createObject( $fields );
+        $this->assertEquals( $object['content'], 'This is a note' );
+        $this->assertNull( $object['attributedTo'] );
+    }
+
+    public function testItThrowsTryingToSetObjectFieldLikeArray()
+    {
+        $fields = array(
+            'id' => 'https://example.com/notes/1',
+            'type' => 'Note',
+            'content' => 'This is a note',
+        );
+        $now = $this->getTime( 'create' );
+        $object = $this->objectsService->createObject( $fields );
+        $this->expectException( BadMethodCallException::class );
+        $object['content'] = 'This should break';
+    }
+
+    public function testItThrowsTryingToUnsetObjectFieldLikeArray()
+    {
+        $fields = array(
+            'id' => 'https://example.com/notes/1',
+            'type' => 'Note',
+            'content' => 'This is a note',
+        );
+        $now = $this->getTime( 'create' );
+        $object = $this->objectsService->createObject( $fields );
+        $this->expectException( BadMethodCallException::class );
+        unset( $object['content'] );
+    }
 }
 ?>