Require confirmation date to be set in the data model #2714

data-serving/reusable-data-service/pyproject.toml

@@ -8,7 +8,7 @@ authors = ["Global.health <info@global.health>"]
 python = "^3.10"
 
 [tool.poetry.dev-dependencies]
-pytest = "^5.2"
+pytest = "^7.1.2"
 
 [build-system]
 requires = ["poetry-core>=1.0.0"]

data-serving/reusable-data-service/reusable_data_service/model/case.py

@@ -1,11 +1,37 @@
 import dataclasses
+import datetime
+import json
 
-@dataclasses.dataclass
+@dataclasses.dataclass()
 class DayZeroCase:
     """This class implements the "day-zero" data schema for Global.health.
     At the beginning of an outbreak, we want to collect at least this much
-    information about an individual case for the line list."""
-    pass
+    information about an individual case for the line list.
+    
+    Parameters here are defined to be keyword-only and not set in the
+    initialiser, so that clients can use Builder to populate them. Use
+    the validate() method to determine whether an instance is in a
+    consistent state (this also means we can add custom validation logic
+    to that function)."""
+    _: dataclasses.KW_ONLY
+    confirmation_date: datetime.datetime = dataclasses.field(init=False)
+
+    @classmethod
+    def from_json(cls, obj: str) -> type:
+        """Create an instance of this class from a JSON representation."""
+        case = cls()
+        source = json.loads(obj)
+        for key in source:
+            setattr(case, key, source[key])
+        case.validate()
+        return case
+
+    def validate(self):
+        """Check whether I am consistent. Raise ValueError if not."""
+        if not hasattr(self, 'confirmation_date'):
+            raise ValueError("Confirmation Date is mandatory")
+        elif self.confirmation_date is None:
+            raise ValueError("Confirmation Date must have a value")
 
 # Actually we want to capture extra fields which can be specified dynamically:
 # so Case is the class that you should use.

data-serving/reusable-data-service/tests/test_case_model.py

@@ -1,5 +1,6 @@
+import pytest
 from reusable_data_service import Case
 
-def test_instantiating_case():
-    case = Case()
-    assert case is not None
+def test_instantiating_case_from_empty_json_is_error():
+    with pytest.raises(ValueError):
+        case = Case.from_json('{}')