Implement do_snapshot() and has_changed() methods to determine change…

…s in BaseModel

osc/util/models.py

@@ -385,8 +385,16 @@ def __init__(self, **kwargs):
         for name, field in self.__fields__.items():
             field.validate_type(getattr(self, name))
 
+        self._snapshot = {}  # copy of ``self.dict()`` so we can determine if the object has changed later on
+        self.do_snapshot()
+
         self._allow_new_attributes = False
 
+    def __eq__(self, other):
+        if type(self) != type(other):
+            return False
+        return self.dict() == other.dict()
+
     def dict(self):
         result = {}
         for name, field in self.__fields__.items():
@@ -402,6 +410,18 @@ def dict(self):
 
         return result
 
+    def do_snapshot(self):
+        """
+        Save ``self.dict()`` result as a new starting point for detecting changes in the object data.
+        """
+        self._snapshot = self.dict()
+
+    def has_changed(self):
+        """
+        Determine if the object data has changed since its creation or the last snapshot.
+        """
+        return self.dict() != self._snapshot
+
 
 class XmlModel(BaseModel):
     XML_TAG = None

tests/test_conf.py

@@ -517,7 +517,7 @@ def test_api_host_options(self):
         conf1 = osc.conf.Options()
         conf2 = osc.conf.Options()
 
-        self.assertNotEqual(conf1, conf2)
+        self.assertEqual(conf1, conf2)  # models are compared by their contents now
         self.assertNotEqual(id(conf1), id(conf2))
         self.assertNotEqual(id(conf1.api_host_options), id(conf2.api_host_options))
 

tests/test_models.py

@@ -316,6 +316,29 @@ class Model(BaseModel):
         self.assertEqual(m.quiet, False)
         self.assertEqual(m.verbose, True)
 
+    def test_has_changed(self):
+        class TestSubmodel(BaseModel):
+            text: str = Field(default="default")
+
+        class TestModel(BaseModel):
+            field: Optional[List[TestSubmodel]] = Field(default=[])
+
+        m = TestModel()
+        self.assertFalse(m.has_changed())
+
+        # a new instance of empty list
+        m.field = []
+        self.assertFalse(m.has_changed())
+
+        m.field = [{"text": "one"}, {"text": "two"}]
+        self.assertTrue(m.has_changed())
+
+        m.do_snapshot()
+
+        # a new instance of list with new instances of objects with the same data
+        m.field = [{"text": "one"}, {"text": "two"}]
+        self.assertFalse(m.has_changed())
+
 
 if __name__ == "__main__":
     unittest.main()