Updated PaginationType to allow custom fields to be injected (#118)

* Updated PaginationType to allow custom fields to be injected

* Updated name of project in composer.json

Author: nigeldgreen

docs/advanced.md

@@ -454,12 +454,94 @@ Query `posts(limit:10,page:1){data{id},total,per_page}` might return
                 ...
             ],
             "total": 21,
-            "per_page": 10"
+            "per_page": 10
         ]
     }
 }
 ```
 
+Note that you need to add in the extra 'data' object when you request paginated resources as the returned data gives you
+the paginated resources in a data object at the same level as the returned pagination metadata.
+
+#### Customising the pagination results
+You can add in additional metadata results alongside the Laravel 'standard' ones. To keep the Posts theme going, we could 
+create some additional metadata to show the total number of posts, comments and likes for the posts returned in the paginated 
+results.
+
+First, create a class that returns the custom fields you want to see:
+
+```
+use Illuminate\Pagination\LengthAwarePaginator;
+use GraphQL\Type\Definition\Type as GraphQLType;
+
+class MyCustomPaginationFields
+{
+    public static function getPaginationFields()
+    {
+        return [
+            // Pass through a User object that we can use to calculate the totals
+            'totals_for_user' => [
+                'type'          => \GraphQL::type('total'),
+                'description'   => 'Total posts, comments and likes for the result set',
+                'resolve'       => function () {
+                    return app()->make('App\User');
+                },
+                'selectable'    => false,
+            ],
+            // Add in the 'last page' value from the Laravel Paginator
+            'last_page' => [
+                'type'          => GraphQLType::nonNull(GraphQLType::int()),
+                'description'   => 'Last page of the result set',
+                'resolve'       => function (LengthAwarePaginator $data) {
+                    return $data->lastPage();
+                },
+                'selectable'    => false,
+            ],
+        ];
+    }
+}
+```
+
+Then add a config entry to map this class:
+
+```
+'custom_paginators' => [
+    'post_pagination' => \Namespace\Of\The\MyCustomPaginationFields::class,
+],
+```
+You can now query against the new fields in the same way as for the core pagination metadata. We could now extend the example 
+query from earlier to get the new fields.
+
+Query: `posts(limit:10,page:1){data{id},totals_for_user,total,per_page,last_page}`:
+
+```
+{
+    "data": {
+        "posts: [
+            "data": [
+                {"id": 3},
+                {"id": 5},
+                ...
+            ],
+            "totals_for_user": [
+                {"posts": 12},
+                {"comments": 42},
+                {"likes": 101}
+            ],
+            "total": 21,
+            "per_page": 10,
+            "last_page": 3
+        ]
+    }
+}
+```
+
+ 
+If you want to change the name of a default field to fit with users expectations (maybe you want 'total_records' rather 
+than 'total'), just copy the entry for the field you want to replace (they're in Rebing/GraphQL/Support/PaginationType.php) 
+and add it to your custom class.
+
+
 ### Batching
 
 You can send multiple queries (or mutations) at once by grouping them together. Therefore, instead of creating two HTTP requests:

src/Rebing/GraphQL/Support/PaginationType.php

@@ -12,14 +12,22 @@ class PaginationType extends ObjectType {
     public function __construct($typeName, $customName = null)
     {
         $name = $customName ?: $typeName . '_pagination';
+
+        $customPaginator = config('graphql.custom_paginators.' . $name, null);
+        $customFields = $customPaginator ? $customPaginator::getPaginationFields() : [];
+
         $config = [
             'name'  => $name,
-            'fields' => array_merge($this->getPaginationFields(), [
-                'data' => [
-                    'type'      => GraphQLType::listOf(GraphQL::type($typeName)),
-                    'resolve'   => function(LengthAwarePaginator $data) { return $data->getCollection();  },
-                ],
-            ])
+            'fields' => array_merge(
+                $this->getPaginationFields(),
+                $customFields,
+                [
+                    'data' => [
+                        'type'      => GraphQLType::listOf(GraphQL::type($typeName)),
+                        'resolve'   => function(LengthAwarePaginator $data) { return $data->getCollection();  },
+                    ],
+                ]
+            )
         ];
 
         parent::__construct($config);
@@ -61,4 +69,4 @@ protected function getPaginationFields()
         ];
     }
 
-}
+}

src/config/config.php

@@ -139,6 +139,14 @@
         'disable_introspection' => false
     ],
 
+    // You can define custom paginators to override the out-of-the-box fields
+    // Useful if you want to inject some parameters of your own that apply at the top
+    // level of the collection rather than to each instance returned. Can also use this
+    // to add in more of the Laravel pagination data (e.g. last_page).
+    'custom_paginators' => [
+        // 'my_custom_pagination' => \Path\To\Your\CustomPagination::class,
+    ],
+
     /*
      * Config for GraphiQL (see (https://github.com/graphql/graphiql).
      */