Added "non_relation_field" to types with documentation (#140)

* Added "non_relation_field" to types with documentation

* Changed "non_relation_field" to "is_relation"

Whether the nested object is a relation is now an opt-out instead of an opt-in configuration.

* Update SelectFields.php

Author: roelofjan-elsinga

docs/advanced.md

@@ -12,6 +12,7 @@
 - [Unions](#unions)
 - [Interfaces](#interfaces)
 - [Input Object](#input-object)
+- [JSON Columns](#json-columns)
 
 ### Authorization
 
@@ -881,3 +882,35 @@ class TestMutation extends GraphQLType {
 
 }
 ```
+
+### JSON Columns
+
+When using JSON columns in your database, the field won't be defined as a "relationship", 
+but rather a simple column with nested data. To get a nested object that's not a database relationship, 
+use the `non_relation_field` attribute in your Type:
+
+```php
+class UserType extends GraphQLType {
+
+    ...
+    
+    public function fields()
+    {
+        return [
+            
+            ...
+            
+            // JSON column containing all posts made by this user
+            'posts' => [
+                'type'          => Type::listOf(GraphQL::type('post')),
+                'description'   => 'A list of posts written by the user',
+                // Now this will simply request the "posts" column, and it won't 
+                // query for all the underlying columns in the "post" object
+                // The value defaults to true
+                'is_relation' => false
+            ]
+        ];
+    }
+
+}
+```

src/Rebing/GraphQL/Support/SelectFields.php

@@ -140,13 +140,16 @@ protected static function handleFields(array $requestedFields, $parentType, arra
                 // Add a query, if it exists
                 $customQuery = array_get($fieldObject->config, 'query');
 
+                // Check if the field is a relation that needs to be requested from the DB
+                $queryable = self::isQueryable($fieldObject);
+
                 // Pagination
                 if(is_a($parentType, PaginationType::class))
                 {
                     self::handleFields($field, $fieldObject->config['type']->getWrappedType(), $select, $with);
                 }
                 // With
-                elseif(is_array($field))
+                elseif(is_array($field) && $queryable)
                 {
                     if (isset($parentType->config['model']))
                     {
@@ -297,6 +300,16 @@ protected static function validateField($fieldObject)
         return $selectable;
     }
 
+    /**
+     * Determines whether the fieldObject is queryable.
+     *
+     * @param $fieldObject
+     * @return bool
+     */
+    private static function isQueryable($fieldObject) {
+        return array_get($fieldObject, 'is_relation', true) === true;
+    }
+
     /**
      * Add selects that are given by the 'always' attribute
      */