Allow fields to be made only visible for single root resources

src/Handler/Show.php

@@ -35,7 +35,7 @@ class Show implements RequestHandlerInterface
 
         $serializer = new Serializer($this->api, $request);
 
-        $serializer->add($this->resource, $this->model, $include);
+        $serializer->add($this->resource, $this->model, $include, true);
 
         return new JsonApiResponse(
             new CompoundDocument(

src/Schema/Field.php

@@ -14,6 +14,7 @@ abstract class Field
     private $name;
     private $property;
     private $visible = true;
+    private $single = false;
     private $writable = false;
     private $getter;
     private $setter;
@@ -49,6 +50,18 @@ abstract class Field
         return $this;
     }
 
+    /**
+     * Indicates that the field should only be visible on single root resources
+     *
+     * @return $this
+     */
+    public function single()
+    {
+        $this->single = true;
+
+        return $this;
+    }
+
     public function writable(Closure $condition = null)
     {
         $this->writable = $condition ?: true;
@@ -137,6 +150,11 @@ abstract class Field
         return $this->visible;
     }
 
+    public function getSingle()
+    {
+        return $this->single;
+    }
+
     public function getWritable()
     {
         return $this->writable;

src/Serializer.php

@@ -30,14 +30,14 @@ final class Serializer
         $this->request = $request;
     }
 
-    public function add(ResourceType $resource, $model, array $include)
+    public function add(ResourceType $resource, $model, array $include, bool $single = false)
     {
-        $data = $this->addToMap($resource, $model, $include);
+        $data = $this->addToMap($resource, $model, $include, $single);
 
         $this->primary[] = $data['type'].':'.$data['id'];
     }
 
-    private function addToMap(ResourceType $resource, $model, array $include)
+    private function addToMap(ResourceType $resource, $model, array $include, bool $single = false)
     {
         $adapter = $resource->getAdapter();
         $schema = $resource->getSchema();
@@ -69,6 +69,10 @@ final class Serializer
                 continue;
             }
 
+            if ($field->getSingle() && ! $single) {
+                continue;
+            }
+
             if (! evaluate($field->getVisible(), [$model, $this->request])) {
                 continue;
             }