# GET handlers
 
+    @staticmethod
+    def _get_item(target_class: Any
+                  ) -> Callable[..., Callable[[TaskHandler],
+                                              dict[str, object]]]:
+        def decorator(f: Callable[..., dict[str, object]]
+                      ) -> Callable[[TaskHandler], dict[str, object]]:
+            def wrapper(self: TaskHandler) -> dict[str, object]:
+                # pylint: disable=protected-access
+                # (because pylint here fails to detect the use of wrapper as a
+                # method to self with respective access privileges)
+                id_ = self._params.get_int_or_none('id')
+                if target_class.can_create_by_id:
+                    item = target_class.by_id_or_create(self.conn, id_)
+                else:
+                    item = target_class.by_id(self.conn, id_)
+                return f(self, item)
+            return wrapper
+        return decorator
+
     def do_GET_(self) -> str:
         """Return redirect target on GET /."""
         return '/day'
                 'conditions_present': conditions_present,
                 'processes': Process.all(self.conn)}
 
-    def do_GET_todo(self) -> dict[str, object]:
+    @_get_item(Todo)
+    def do_GET_todo(self, todo: Todo) -> dict[str, object]:
         """Show single Todo of ?id=."""
 
         @dataclass
                 ids = ids | collect_adoptables_keys(node.children)
             return ids
 
-        id_ = self._params.get_int('id')
-        todo = Todo.by_id(self.conn, id_)
         todo_steps = [step.todo for step in todo.get_step_tree(set()).children]
         process_tree = todo.process.get_steps(self.conn, None)
         steps_todo_to_process: list[TodoStepsNode] = []
                 'sort_by': sort_by,
                 'pattern': pattern}
 
-    def do_GET_condition(self) -> dict[str, object]:
+    @_get_item(Condition)
+    def do_GET_condition(self, c: Condition) -> dict[str, object]:
         """Show Condition of ?id=."""
-        id_ = self._params.get_int_or_none('id')
-        c = Condition.by_id_or_create(self.conn, id_)
         ps = Process.all(self.conn)
         return {'condition': c, 'is_new': c.id_ is None,
                 'enabled_processes': [p for p in ps if c in p.conditions],
                 'enabling_processes': [p for p in ps if c in p.enables],
                 'disabling_processes': [p for p in ps if c in p.disables]}
 
-    def do_GET_condition_titles(self) -> dict[str, object]:
+    @_get_item(Condition)
+    def do_GET_condition_titles(self, c: Condition) -> dict[str, object]:
         """Show title history of Condition of ?id=."""
-        id_ = self._params.get_int('id')
-        condition = Condition.by_id(self.conn, id_)
-        return {'condition': condition}
+        return {'condition': c}
 
-    def do_GET_condition_descriptions(self) -> dict[str, object]:
+    @_get_item(Condition)
+    def do_GET_condition_descriptions(self, c: Condition) -> dict[str, object]:
         """Show description historys of Condition of ?id=."""
-        id_ = self._params.get_int('id')
-        condition = Condition.by_id(self.conn, id_)
-        return {'condition': condition}
+        return {'condition': c}
 
-    def do_GET_process(self) -> dict[str, object]:
+    @_get_item(Process)
+    def do_GET_process(self, process: Process) -> dict[str, object]:
         """Show Process of ?id=."""
-        id_ = self._params.get_int_or_none('id')
-        process = Process.by_id_or_create(self.conn, id_)
         title_64 = self._params.get_str('title_b64')
         if title_64:
             title = b64decode(title_64.encode()).decode()
                 'process_candidates': Process.all(self.conn),
                 'condition_candidates': Condition.all(self.conn)}
 
-    def do_GET_process_titles(self) -> dict[str, object]:
+    @_get_item(Process)
+    def do_GET_process_titles(self, p: Process) -> dict[str, object]:
         """Show title history of Process of ?id=."""
-        id_ = self._params.get_int('id')
-        process = Process.by_id(self.conn, id_)
-        return {'process': process}
+        return {'process': p}
 
-    def do_GET_process_descriptions(self) -> dict[str, object]:
+    @_get_item(Process)
+    def do_GET_process_descriptions(self, p: Process) -> dict[str, object]:
         """Show description historys of Process of ?id=."""
-        id_ = self._params.get_int('id')
-        process = Process.by_id(self.conn, id_)
-        return {'process': process}
+        return {'process': p}
 
-    def do_GET_process_efforts(self) -> dict[str, object]:
+    @_get_item(Process)
+    def do_GET_process_efforts(self, p: Process) -> dict[str, object]:
         """Show default effort history of Process of ?id=."""
-        id_ = self._params.get_int('id')
-        process = Process.by_id(self.conn, id_)
-        return {'process': process}
+        return {'process': p}
 
     def do_GET_processes(self) -> dict[str, object]:
         """Show all Processes."""