[IMP] server_environment: Preserve not env managed data

Helper function typically used for hooks and migration scripts.
Restores database values for fields transitioning to 'server env managed'.

When a field is defined as managed by the server environment, Odoo
ignores the value stored in the database, prioritizing the environment
configuration instead. If no environment configuration exists, the field
may effectively lose its previous value.

This method forces to 'persist' these values if they are not
explicitly overridden by the current environment configuration.

Author: qgroulard

server_environment/models/server_env_mixin.py

@@ -428,3 +428,33 @@ def _setup_base(self):
             self._server_env_transform_field_to_read_from_env(field)
             self._server_env_add_is_editable_field(field)
         return
+
+    @api.model
+    def preserve_not_env_managed_data(self):
+        """
+        Helper function typically used for hooks and migration scripts.
+        Restores database values for fields transitioning to 'server env managed'.
+
+        When a field is defined as managed by the server environment, Odoo
+        ignores the value stored in the database, prioritizing the environment
+        configuration instead. If no environment configuration exists, the field
+        may effectively lose its previous value.
+
+        This method forces to 'persist' these values if they are not
+        explicitly overridden by the current environment configuration.
+        """
+        self.env.cr.execute(f"SELECT * FROM {self._table}")
+        for row in self.env.cr.dictfetchall():
+            record = (
+                self.env[self._name]
+                .with_context(active_test=False)
+                .search([("id", "=", row["id"])])
+            )
+            if record:
+                record_values = {}
+                for field_name, _options in self.env[
+                    self._name.replace(".", "_")
+                ]._server_env_fields.items():
+                    if field_name in row:
+                        record_values[field_name] = row[field_name]
+                record.update(record_values)