make channel fields optional

PiperOrigin-RevId: 429085129

Author: shuklak13

model_card_toolkit/tfx/component.py

@@ -34,12 +34,13 @@ class ModelCardGeneratorSpec(component_spec.ComponentSpec):
   INPUTS = {
       standard_component_specs.STATISTICS_KEY:
           component_spec.ChannelParameter(
-              type=standard_artifacts.ExampleStatistics),
+              type=standard_artifacts.ExampleStatistics, optional=True),
       standard_component_specs.EVALUATION_KEY:
           component_spec.ChannelParameter(
-              type=standard_artifacts.ModelEvaluation),
+              type=standard_artifacts.ModelEvaluation, optional=True),
       standard_component_specs.PUSHED_MODEL_KEY:
-          component_spec.ChannelParameter(type=standard_artifacts.PushedModel),
+          component_spec.ChannelParameter(
+              type=standard_artifacts.PushedModel, optional=True),
   }
   OUTPUTS = {
       MODEL_CARD_KEY:

model_card_toolkit/tfx/component_test.py

@@ -50,6 +50,12 @@ def test_component_construction(self):
                               ('path/to/md/template', 'mc.md')]
           }, this_component.exec_properties)
 
+  def test_empty_component_construction(self):
+    this_component = ModelCardGenerator()
+    with self.subTest('outputs'):
+      self.assertEqual(this_component.outputs['model_card'].type_name,
+                       artifact.ModelCard.TYPE_NAME)
+
 
 if __name__ == '__main__':
   absltest.main()