Don't use post_init signal for initialize tracker

AUTHORS.rst

@@ -104,3 +104,4 @@
 | Éric Araujo <[email protected]>
 | Őry Máté <[email protected]>
 | Nafees Anwar <[email protected]>
+| meanmail <[email protected]>

CHANGES.rst

@@ -1,10 +1,15 @@
 Changelog
 =========
 
+4.5.0
+-----
+
+- Don't use `post_init` signal for initialize tracker
+
 4.4.0 (2024-02-10)
 ------------------
 
-- Add support for `Python 3.11` 
+- Add support for `Python 3.11`
 - Add support for `Python 3.12`
 - Drop support for `Python 3.7`
 - Add support for `Django 4.2`

docs/utilities.rst

@@ -328,9 +328,9 @@ FieldTracker implementation details
 
 This is how ``FieldTracker`` tracks field changes on ``instance.save`` call.
 
-1. In ``class_prepared`` handler ``FieldTracker`` patches ``save_base`` and
-   ``refresh_from_db`` methods to reset initial state for tracked fields.
-2. In ``post_init`` handler ``FieldTracker`` saves initial values for tracked
+1. In ``class_prepared`` handler ``FieldTracker`` patches ``save_base``,
+   ``refresh_from_db`` and ``__init__`` methods to reset initial state for tracked fields.
+2. In the patched ``__init__`` method ``FieldTracker`` saves initial values for tracked
    fields.
 3. ``MyModel.save`` changes ``update_fields`` in order to store auto updated
    ``modified`` timestamp. Complete list of saved fields is now known.

model_utils/tracker.py

@@ -343,7 +343,7 @@ def finalize_class(self, sender, **kwargs):
             wrapped_descriptor = wrapper_cls(field_name, descriptor, self.attname)
             setattr(sender, field_name, wrapped_descriptor)
         self.field_map = self.get_field_map(sender)
-        models.signals.post_init.connect(self.initialize_tracker)
+        self.patch_init(sender)
         self.model_class = sender
         setattr(sender, self.name, self)
         self.patch_save(sender)
@@ -356,6 +356,16 @@ def initialize_tracker(self, sender, instance, **kwargs):
         tracker.set_saved_fields()
         instance._instance_initialized = True
 
+    def patch_init(self, model):
+        original = getattr(model, '__init__')
+
+        @wraps(original)
+        def inner(instance, *args, **kwargs):
+            original(instance, *args, **kwargs)
+            self.initialize_tracker(model, instance)
+
+        setattr(model, '__init__', inner)
+
     def patch_save(self, model):
         self._patch(model, 'save_base', 'update_fields')
         self._patch(model, 'refresh_from_db', 'fields')