Added a basic version of a JSON service

CHANGELOG.md

@@ -23,6 +23,8 @@
   [#379](https://github.com./nextcloud/cookbook/pull/379/) @seyfeb
 - Selectable keywords for filtering in recipe lists
   [#375](https://github.com./nextcloud/cookbook/pull/375/) @seyfeb
+- Service to handle schema.org JSON data in strings easier
+  [#383](https://github.com./nextcloud/cookbook/pull/383/) @christianlupus
 
 ### Changed
 - Switch of project ownership to neextcloud organization in GitHub

lib/Service/JsonService.php

@@ -0,0 +1,65 @@
+<?php
+
+namespace OCA\Cookbook;
+
+/**
+ * A collection of useful functions to handle schema.org JSON data
+ * 
+ * @author Christian Wolf <[email protected]>
+ *
+ */
+class JsonService
+{
+
+    /**
+     * Check if an object is a JSON representation of a schema.org object
+     *
+     * The type of the object can be optionally checked using the second parameter.
+     *
+     * @param mixed $obj The object to check
+     * @param string $type The type to check for. If null or '' no type chek is performed
+     * @return bool true, if $obj is an object and optionally satisfies the type check
+     */
+    public function isSchemaObject($obj, string $type = null) : bool
+    {
+        if(! is_array($obj))
+        {
+            // Objects must bve encoded as arrays in JSON
+            return false;
+        }
+
+        if(!isset($obj['@type']))
+        {
+            // Objects must have a property @type
+            return false;
+        }
+
+        // We have an object
+
+        if($type === null || $type === '')
+        {
+            // No typecheck was requested. So return true
+            return true;
+        }
+
+        // Check if type matches
+        return (strcmp($obj['@type'], $type) == 0);
+    }
+
+    /**
+     * Check if $obj is a schema.org object and contains a named property.
+     * 
+     * @param mixed $obj The object to check
+     * @param string $property The name of the property to check for
+     * @return bool true, if $obj is a object and has the property given
+     */
+    public function hasProperty($obj, string $property) : bool
+    {
+        if(!$this->isSchemaObject($obj))
+        {
+            return false;
+        }
+
+        return array_key_exists($property, $obj);
+    }
+}