Require default interface for algorithm (#3759)

Adds a check to both the form and the model that ensures that an
algorithm has a default interface. We're not using the through model
directly to create an interface for an algorithm through the UI, hence
the check in 2 places.

app/grandchallenge/algorithms/forms.py

@@ -1377,6 +1377,14 @@ def __init__(self, *args, algorithm, **kwargs):
         if not self._algorithm.default_interface:
             self.fields["set_as_default"].initial = True
 
+    def clean_set_as_default(self):
+        set_as_default = self.cleaned_data["set_as_default"]
+
+        if not set_as_default and not self._algorithm.default_interface:
+            raise ValidationError("Your algorithm needs a default interface.")
+
+        return set_as_default
+
     def clean(self):
         cleaned_data = super().clean()
 

app/grandchallenge/algorithms/models.py

@@ -634,6 +634,12 @@ class Meta:
     def __str__(self):
         return str(self.interface)
 
+    def clean(self):
+        super().clean()
+
+        if not self.is_default and not self.algorithm.default_interface:
+            raise ValidationError("This algorithm needs a default interface.")
+
 
 class AlgorithmUserObjectPermission(UserObjectPermissionBase):
     content_object = models.ForeignKey(Algorithm, on_delete=models.CASCADE)

app/tests/algorithms_tests/test_forms.py

@@ -1364,6 +1364,30 @@ def test_algorithm_interface_disjoint_interfaces():
     assert "The sets of Inputs and Outputs must be unique" in str(form.errors)
 
 
+@pytest.mark.django_db
+def test_algorithm_interface_default_interface_required():
+    ci1, ci2 = ComponentInterfaceFactory.create_batch(2)
+    alg = AlgorithmFactory()
+    form = AlgorithmInterfaceForm(
+        algorithm=alg,
+        data={"inputs": [ci1], "outputs": [ci2], "set_as_default": False},
+    )
+    assert form.is_valid() is False
+    assert "Your algorithm needs a default interface" in str(
+        form.errors["set_as_default"]
+    )
+
+    alg.interfaces.add(
+        AlgorithmInterfaceFactory(), through_defaults={"is_default": True}
+    )
+    del alg.default_interface
+    form = AlgorithmInterfaceForm(
+        algorithm=alg,
+        data={"inputs": [ci1], "outputs": [ci2], "set_as_default": False},
+    )
+    assert form.is_valid()
+
+
 def test_algorithm_for_phase_form_memory():
     form = AlgorithmForPhaseForm(
         workstation_config=WorkstationConfigFactory.build(),
@@ -1427,7 +1451,7 @@ def test_existing_io_is_reused(self):
             data={
                 "inputs": [inp.pk],
                 "outputs": [out.pk],
-                "set_as_default": False,
+                "set_as_default": True,
             },
         )
         assert form.is_valid()