allow None in eval response (#715)

Author: ekorman

api/tests/unit-tests/schemas/test_evaluation.py

@@ -382,3 +382,20 @@ def test_EvaluationResponse():
             created_at=datetime.now(),
             meta={},
         )
+
+    # test validation for meta
+    er = schemas.EvaluationResponse(
+        id=1,
+        dataset_names=["ds"],
+        model_name="test",
+        filters=schemas.Filter(),
+        parameters=schemas.EvaluationParameters(
+            task_type=enums.TaskType.CLASSIFICATION,
+        ),
+        status=enums.EvaluationStatus.DONE,
+        metrics=[],
+        confusion_matrices=[],
+        created_at=datetime.now(),
+        meta=None,
+    )
+    assert er.meta == {}

api/valor_api/schemas/evaluation.py

@@ -276,7 +276,7 @@ class EvaluationResponse(BaseModel):
     parameters: EvaluationParameters
     status: EvaluationStatus
     created_at: datetime.datetime
-    meta: dict[str, str | int | float] | None
+    meta: dict[str, str | int | float] | None = {}
     metrics: list[Metric] | None = None
     confusion_matrices: list[ConfusionMatrixResponse] | None = None
     ignored_pred_labels: list[Label] | None = None
@@ -286,3 +286,9 @@ class EvaluationResponse(BaseModel):
     model_config = ConfigDict(
         extra="allow", protected_namespaces=("protected_",)
     )
+
+    # make sure that `meta` is a dictionary
+    @field_validator("meta")
+    @classmethod
+    def null_to_empty_dict(cls, v):
+        return v or {}