Make SDK models pickleable (#8746)

Currently, they aren't (or rather, they can be pickled, but unpickling
fails). This is due to a small quirk of how the model classes work, and
is easily worked around.

In addition, don't create a new Configuration object for each model.
These objects are pretty beefy, and they increase the size of each
pickle by a full kilobyte (and of course they increase memory usage even
when pickle is not involved). AFAICS, these objects are only used when
assigning values to file-type fields, and it's easy enough to rewrite
the logic so that it still works when the model's `_configuration` field
is None.

changelog.d/20241127_132256_roman_pickle_models.md

@@ -0,0 +1,4 @@
+### Added
+
+- \[SDK\] Model instances can now be pickled
+  (<https://github.com/cvat-ai/cvat/pull/8746>)

cvat-sdk/gen/templates/openapi-generator/model_templates/method_from_openapi_data_composed.mustache

@@ -22,7 +22,6 @@
             {{name}} ({{{dataType}}}):{{#description}} {{{.}}}.{{/description}} [optional]{{#defaultValue}} if omitted the server will use the default value of {{{.}}}{{/defaultValue}}  # noqa: E501
 {{/optionalVars}}
         """
-        from {{packageName}}.configuration import Configuration
 
 {{#requiredVars}}
 {{#defaultValue}}
@@ -32,7 +31,7 @@
         _check_type = kwargs.pop('_check_type', True)
         _spec_property_naming = kwargs.pop('_spec_property_naming', False)
         _path_to_item = kwargs.pop('_path_to_item', ())
-        _configuration = kwargs.pop('_configuration', Configuration())
+        _configuration = kwargs.pop('_configuration', None)
         _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
 
         self = super(OpenApiModel, cls).__new__(cls)

cvat-sdk/gen/templates/openapi-generator/model_templates/method_from_openapi_data_shared.mustache

@@ -27,7 +27,6 @@
 {{/optionalVars}}
 {{> model_templates/docstring_init_required_kwargs }}
 """
-        from {{packageName}}.configuration import Configuration
 
 {{#requiredVars}}
 {{#defaultValue}}
@@ -37,7 +36,7 @@
         _check_type = kwargs.pop('_check_type', True)
         _spec_property_naming = kwargs.pop('_spec_property_naming', True)
         _path_to_item = kwargs.pop('_path_to_item', ())
-        _configuration = kwargs.pop('_configuration', Configuration())
+        _configuration = kwargs.pop('_configuration', None)
         _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
 
         self = super(OpenApiModel, cls).__new__(cls)

cvat-sdk/gen/templates/openapi-generator/model_templates/method_from_openapi_data_simple.mustache

@@ -12,7 +12,6 @@
             value ({{{dataType}}}):{{#description}} {{{.}}}.{{/description}}{{#defaultValue}} if omitted defaults to {{{.}}}{{/defaultValue}}{{#allowableValues}}, must be one of [{{#enumVars}}{{{value}}}, {{/enumVars}}]{{/allowableValues}}  # noqa: E501
 {{> model_templates/docstring_init_required_kwargs }}
         """
-        from {{packageName}}.configuration import Configuration
 
         # required up here when default value is not given
         _path_to_item = kwargs.pop('_path_to_item', ())
@@ -39,7 +38,7 @@
 
         _check_type = kwargs.pop('_check_type', True)
         _spec_property_naming = kwargs.pop('_spec_property_naming', False)
-        _configuration = kwargs.pop('_configuration', Configuration())
+        _configuration = kwargs.pop('_configuration', None)
         _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
 
 {{> model_templates/invalid_pos_args }}

cvat-sdk/gen/templates/openapi-generator/model_templates/method_init_shared.mustache

@@ -30,7 +30,6 @@
 {{/optionalVars}}
 {{> model_templates/docstring_init_required_kwargs }}
 """
-        from {{packageName}}.configuration import Configuration
 
 {{#requiredVars}}
 {{^isReadOnly}}
@@ -42,7 +41,7 @@
         _check_type = kwargs.pop('_check_type', True)
         _spec_property_naming = kwargs.pop('_spec_property_naming', False)
         _path_to_item = kwargs.pop('_path_to_item', ())
-        _configuration = kwargs.pop('_configuration', Configuration())
+        _configuration = kwargs.pop('_configuration', None)
         _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
 
 {{> model_templates/invalid_pos_args }}

cvat-sdk/gen/templates/openapi-generator/model_templates/method_init_simple.mustache

@@ -20,7 +20,6 @@
             value ({{{dataType}}}):{{#description}} {{{.}}}.{{/description}}{{#defaultValue}} if omitted defaults to {{{.}}}{{/defaultValue}}{{#allowableValues}}, must be one of [{{#enumVars}}{{{value}}}, {{/enumVars}}]{{/allowableValues}}  # noqa: E501
 {{> model_templates/docstring_init_required_kwargs }}
         """
-        from {{packageName}}.configuration import Configuration
 
         # required up here when default value is not given
         _path_to_item = kwargs.pop('_path_to_item', ())
@@ -45,7 +44,7 @@
 
         _check_type = kwargs.pop('_check_type', True)
         _spec_property_naming = kwargs.pop('_spec_property_naming', False)
-        _configuration = kwargs.pop('_configuration', Configuration())
+        _configuration = kwargs.pop('_configuration', None)
         _visited_composed_classes = kwargs.pop('_visited_composed_classes', ())
 
 {{> model_templates/invalid_pos_args }}

cvat-sdk/gen/templates/openapi-generator/model_utils.mustache

@@ -354,6 +354,13 @@ class OpenApiModel(object):
         new_inst = new_cls._new_from_openapi_data(*args, **kwargs)
         return new_inst
 
+    def __setstate__(self, state):
+        # This is the same as the default implementation. We override it,
+        # because unpickling attempts to access `obj.__setstate__` on an uninitialized
+        # object, and if this method is not defined, it results in a call to `__getattr__`.
+        # This fails, because `__getattr__` relies on `self._data_store`, which doesn't
+        # exist in an uninitialized object.
+        self.__dict__.update(state)
 
 class ModelSimple(OpenApiModel):
     """the parent class of models whose type != object in their
@@ -1084,7 +1091,7 @@ def deserialize_file(response_data, configuration, content_disposition=None):
         (file_type): the deserialized file which is open
             The user is responsible for closing and reading the file
     """
-    fd, path = tempfile.mkstemp(dir=configuration.temp_folder_path)
+    fd, path = tempfile.mkstemp(dir=configuration.temp_folder_path if configuration else None)
     os.close(fd)
     os.remove(path)
 
@@ -1263,27 +1270,21 @@ def validate_and_convert_types(input_value, required_types_mixed, path_to_item,
     input_class_simple = get_simple_class(input_value)
     valid_type = is_valid_type(input_class_simple, valid_classes)
     if not valid_type:
-        if (configuration
-                or (input_class_simple == dict
-                    and dict not in valid_classes)):
-            # if input_value is not valid_type try to convert it
-            converted_instance = attempt_convert_item(
-                input_value,
-                valid_classes,
-                path_to_item,
-                configuration,
-                spec_property_naming,
-                key_type=False,
-                must_convert=True,
-                check_type=_check_type
-            )
-            return converted_instance
-        else:
-            raise get_type_error(input_value, path_to_item, valid_classes,
-                                 key_type=False)
+        # if input_value is not valid_type try to convert it
+        converted_instance = attempt_convert_item(
+            input_value,
+            valid_classes,
+            path_to_item,
+            configuration,
+            spec_property_naming,
+            key_type=False,
+            must_convert=True,
+            check_type=_check_type
+        )
+        return converted_instance
 
     # input_value's type is in valid_classes
-    if len(valid_classes) > 1 and configuration:
+    if len(valid_classes) > 1:
         # there are valid classes which are not the current class
         valid_classes_coercible = remove_uncoercible(
             valid_classes, input_value, spec_property_naming, must_convert=False)

tests/python/sdk/test_api_wrappers.py

@@ -2,6 +2,7 @@
 #
 # SPDX-License-Identifier: MIT
 
+import pickle
 from copy import deepcopy
 
 from cvat_sdk import models
@@ -112,3 +113,12 @@ def test_models_do_not_return_internal_collections():
     model_data2 = model.to_dict()
 
     assert DeepDiff(model_data1_original, model_data2) == {}
+
+
+def test_models_are_pickleable():
+    model = models.PatchedLabelRequest(id=5, name="person")
+    pickled_model = pickle.dumps(model)
+    unpickled_model = pickle.loads(pickled_model)
+
+    assert unpickled_model.id == model.id
+    assert unpickled_model.name == model.name