Fix performance issue when command table active validation is off (#269)

* Do not validate command table in as_dict() when active validation is off

src/zhinst/toolkit/command_table.py

@@ -466,6 +466,11 @@ def as_dict(self) -> dict:
             :class:`~zhinst.toolkit.exceptions.ValidateError`: The command table
                 does not correspond to the given JSON schema.
 
+        .. versionchanged:: 0.6.2
+
+            Removed validation when `active_validation` is set to `False`.
+                This improves performance when validation is not needed.
+
         .. versionchanged:: 0.4.2
 
             Removed `$schema` key from resulting dictionary.
@@ -474,7 +479,8 @@ def as_dict(self) -> dict:
             "header": self._header.as_dict(),
             "table": self._table.as_list(),
         }
-        _validate_instance(result, self._ct_schema)
+        if self.active_validation:
+            _validate_instance(result, self._ct_schema)
         return result
 
     def update(self, command_table: t.Union[str, dict]) -> None:
@@ -493,7 +499,8 @@ def json_to_dict(json_: t.Union[str, t.Dict]) -> t.Dict:
             return json_  # type: ignore[return-value]
 
         command_table = json_to_dict(copy.deepcopy(command_table))
-        _validate_instance(command_table, self._ct_schema)
+        if self._active_validation:
+            _validate_instance(command_table, self._ct_schema)
 
         def build_nodes(path: t.Optional[ParentEntry], index: int, obj: dict):
             for k, v in obj.items():

tests/command_table/test_command_table.py

@@ -161,6 +161,8 @@ def test_command_table_active_validation_table(command_table_schema):
         ct.table[999999]
     ct = CommandTable(command_table_schema, active_validation=False)
     ct.table[999999].amplitude00.value = 1
+    ct.as_dict()
+    ct.active_validation = True
     with pytest.raises(ValidationError):
         ct.as_dict()