Add a batch set_fields method to Model

src/backend/models/model_item.py

@@ -33,32 +33,34 @@ class ModelItem:
     def __setattr__(self, name: str, value) -> None:
         """If this item is in a `Model`, alert it of attribute changes."""
 
-        if name == "parent_model" or not self.parent_model:
+        if (
+            name == "parent_model" or
+            not self.parent_model or
+            getattr(self, name) == value
+        ):
             super().__setattr__(name, value)
             return
 
-        if getattr(self, name) == value:
-            return
-
         super().__setattr__(name, value)
+        self._notify_parent_model({name: self.serialize_field(name)})
 
+
+    def _notify_parent_model(self, changed_fields: Dict[str, Any]) -> None:
         parent = self.parent_model
 
-        if not parent.sync_id:
+        if not parent or not parent.sync_id or not changed_fields:
             return
 
-        fields = {name: self.serialize_field(name)}
-
         with parent.write_lock:
             index_then = parent._sorted_data.index(self)
             parent._sorted_data.sort()
             index_now = parent._sorted_data.index(self)
 
-            ModelItemSet(parent.sync_id, index_then, index_now, fields)
+            ModelItemSet(parent.sync_id, index_then, index_now, changed_fields)
 
         for sync_id, proxy in parent.proxies.items():
             if sync_id != parent.sync_id:
-                proxy.source_item_set(parent, self.id, self, fields)
+                proxy.source_item_set(parent, self.id, self, changed_fields)
 
 
     def __delattr__(self, name: str) -> None:
@@ -82,3 +84,20 @@ class ModelItem:
                 name.startswith("_") or name in ("parent_model", "serialized")
             )
         }
+
+
+    def set_fields(self, **fields: Any) -> None:
+        """Set multiple fields's values at once.
+
+        The parent model will be resorted only once, and one `ModelItemSet`
+        event will be sent informing QML of all the changed fields.
+        """
+
+        for name, value in fields.copy().items():
+            if getattr(self, name) == value:
+                del fields[name]
+            else:
+                super().__setattr__(name, value)
+                fields[name] = self.serialize_field(name)
+
+        self._notify_parent_model(fields)