🐛 [#4579] Ensure triggerFromStep uses the correct current_step

previously the current step was inferred by looking at the last completed step and considering the step after that the current step. This does not work however if you complete a step and go back to the previous step, so instead we explicitly pass the current form step via the serializer context

Backport-of: #4967

src/openforms/submissions/api/serializers.py

@@ -200,7 +200,11 @@ def create(self, validated_data):
         return super().create(validated_data)
 
     def to_representation(self, instance):
-        check_submission_logic(instance, unsaved_data=self.context.get("unsaved_data"))
+        check_submission_logic(
+            instance,
+            unsaved_data=self.context.get("unsaved_data"),
+            current_step=self.context.get("current_step"),
+        )
         return super().to_representation(instance)
 
 

src/openforms/submissions/api/viewsets.py

@@ -639,6 +639,10 @@ def logic_check(self, request, *args, **kwargs):
 
         submission_state_logic_serializer = SubmissionStateLogicSerializer(
             instance=SubmissionStateLogic(submission=submission, step=submission_step),
-            context={"request": request, "unsaved_data": data},
+            context={
+                "request": request,
+                "unsaved_data": data,
+                "current_step": submission_step,
+            },
         )
         return Response(submission_state_logic_serializer.data)

src/openforms/submissions/form_logic.py

@@ -188,7 +188,9 @@ def evaluate_form_logic(
 
 
 def check_submission_logic(
-    submission: "Submission", unsaved_data: dict | None = None
+    submission: "Submission",
+    unsaved_data: dict | None = None,
+    current_step: "SubmissionStep | None" = None,
 ) -> None:
     if getattr(submission, "_form_logic_evaluated", False):
         return
@@ -198,7 +200,7 @@ def check_submission_logic(
     if not submission_state.form_steps:
         return
 
-    rules = get_rules_to_evaluate(submission)
+    rules = get_rules_to_evaluate(submission, current_step)
 
     # load the data state and all variables
     submission_variables_state = submission.load_submission_value_variables_state()

src/openforms/submissions/tests/form_logic/test_submission_logic.py

@@ -225,6 +225,126 @@ def test_check_logic_on_whole_submission_with_variables(self):
         self.assertTrue(data["steps"][1]["isApplicable"])
         self.assertFalse(data["steps"][1]["canSubmit"])
 
+    @tag("gh-4579")
+    def test_properly_determine_current_step(self):
+        """
+        Assert that the submission logic check properly determines the current step for
+        rules that define `triggerFromStep`
+
+        * We fill out step 1 and continue to step 2
+        * In step two the logic rule triggers that prevents us from continuing
+        * We go back to step 1 and it should be possible to continue to step 2 from there
+        """
+        form = FormFactory.create()
+        step1 = FormStepFactory.create(
+            form=form,
+            form_definition__configuration={
+                "components": [
+                    {
+                        "type": "textfield",
+                        "key": "text1",
+                    }
+                ]
+            },
+        )
+        step2 = FormStepFactory.create(
+            form=form,
+            form_definition__configuration={
+                "components": [
+                    {
+                        "type": "textfield",
+                        "key": "text2",
+                    }
+                ]
+            },
+        )
+        FormVariableFactory.create(
+            form=form,
+            key="verdergaan",
+            user_defined=True,
+            data_type=FormVariableDataTypes.string,
+        )
+        # set up logic rules:
+        # 1. setting `text1` to `trigger-value` should set our user defined variable to `nee`
+        FormLogicFactory.create(
+            form=form,
+            json_logic_trigger={"==": [{"var": "text1"}, "trigger-rule"]},
+            actions=[
+                {
+                    "component": "",
+                    "variable": "verdergaan",
+                    "formStepUuid": None,
+                    "action": {"type": "variable", "value": "nee"},
+                }
+            ],
+        )
+        # 2. if `verdergaan` is `nee`, block going to step3
+        FormLogicFactory.create(
+            form=form,
+            trigger_from_step=step2,
+            json_logic_trigger={"==": [{"var": "verdergaan"}, "nee"]},
+            actions=[
+                {
+                    "component": "",
+                    "formStepUuid": None,
+                    "action": {"type": "disable-next"},
+                }
+            ],
+        )
+        submission = SubmissionFactory.create(form=form)
+        self._add_submission_to_session(submission)
+
+        with self.subTest("fill in step1"):
+            endpoint = reverse(
+                "api:submission-steps-detail",
+                kwargs={
+                    "submission_uuid": submission.uuid,
+                    "step_uuid": step1.uuid,
+                },
+            )
+
+            response = self.client.put(
+                endpoint, data={"data": {"text1": "trigger-rule"}}
+            )
+
+            self.assertEqual(status.HTTP_201_CREATED, response.status_code)
+
+            data = response.json()
+
+            self.assertTrue(data["completed"])
+            self.assertTrue(data["canSubmit"])
+
+        with self.subTest("logic step for step 2 should not allow submitting"):
+            endpoint = reverse(
+                "api:submission-steps-logic-check",
+                kwargs={"submission_uuid": submission.uuid, "step_uuid": step2.uuid},
+            )
+            response = self.client.post(endpoint, data={"data": {"text2": "foo"}})
+
+            self.assertEqual(status.HTTP_200_OK, response.status_code)
+
+            data = response.json()
+
+            self.assertFalse(data["step"]["canSubmit"])
+
+        with self.subTest("logic check for step 1 should still allow submitting"):
+            endpoint = reverse(
+                "api:submission-steps-logic-check",
+                kwargs={"submission_uuid": submission.uuid, "step_uuid": step1.uuid},
+            )
+
+            response = self.client.post(
+                endpoint, data={"data": {"text1": "trigger-rule"}}
+            )
+
+            self.assertEqual(status.HTTP_200_OK, response.status_code)
+
+            data = response.json()
+
+            # It should be possible to go to the next step, because the logic rule
+            # to block going to the next step should only trigger from step2
+            self.assertTrue(data["step"]["canSubmit"])
+
     def test_check_logic_with_full_datetime(self):
         form = FormFactory.create()
         step1 = FormStepFactory.create(