优化绑定属性到父模型时数据获取

src/model/concern/Conversion.php

@@ -132,7 +132,7 @@ public function appendRelationAttr(string $attr, array $append)
                     throw new Exception('bind attr has exists:' . $key);
                 }
 
-                $this->data[$key] = $model->$attr;
+                $this->data[$key] = $model->getAttr($attr);
             }
         }
 

src/model/concern/RelationShip.php

@@ -384,7 +384,7 @@ public function bindAttr(string $relation, array $attrs = [])
                 throw new Exception('bind attr has exists:' . $key);
             }
 
-            $this->set($key, $relation ? $relation->$attr : null);
+            $this->set($key, $relation ? $relation->getAttr($attr) : null);
         }
 
         return $this;

src/model/relation/MorphOne.php

@@ -365,7 +365,7 @@ protected function bindAttr(Model $result, Model $model = null): void
                 throw new Exception('bind attr has exists:' . $key);
             }
 
-            $result->setAttr($key, $model?->$attr);
+            $result->setAttr($key, $model?->getAttr($attr));
         }
     }
 }

src/model/relation/OneToOne.php

@@ -322,7 +322,7 @@ protected function bindAttr(Model $result, Model $model = null): void
                 throw new Exception('bind attr has exists:' . $key);
             }
 
-            $result->setAttr($key, $model?->$attr);
+            $result->setAttr($key, $model?->getAttr($attr));
         }
     }