Add clean method to Relation

backend/label_types/urls.py

@@ -19,7 +19,7 @@ urlpatterns = [
     path(route="span-types/<int:label_id>", view=SpanTypeDetail.as_view(), name="span_type"),
     path(route="category-type-upload", view=CategoryTypeUploadAPI.as_view(), name="category_type_upload"),
     path(route="span-type-upload", view=SpanTypeUploadAPI.as_view(), name="span_type_upload"),
-path(route="relation-type-upload", view=RelationTypeUploadAPI.as_view(), name="relation_type-upload"),
+    path(route="relation-type-upload", view=RelationTypeUploadAPI.as_view(), name="relation_type-upload"),
     path(route="relation-types", view=RelationTypeList.as_view(), name="relation_types_list"),
     path(route="relation-types/<int:label_id>", view=RelationTypeDetail.as_view(), name="relation_type_detail"),
 ]

backend/labels/models.py

@@ -103,3 +103,13 @@ class Relation(Label):
 
     def __str__(self):
         return self.__dict__.__str__()
+
+    def save(self, force_insert=False, force_update=False, using=None, update_fields=None):
+        self.full_clean()
+        super().save(force_insert, force_update, using, update_fields)
+
+    def clean(self):
+        same_example = self.from_id.example == self.to_id.example == self.example
+        if not same_example:
+            raise ValidationError("You need to label the same example.")
+        return super().clean()

backend/labels/tests/test_relation.py

@@ -0,0 +1,32 @@
+from django.core.exceptions import ValidationError
+from django.test import TestCase
+from model_mommy import mommy
+
+from projects.models import SEQUENCE_LABELING
+from projects.tests.utils import prepare_project
+
+
+class TestRelationLabeling(TestCase):
+    @classmethod
+    def setUpTestData(cls):
+        cls.project = prepare_project(SEQUENCE_LABELING)
+        cls.example = mommy.make("Example", project=cls.project.item)
+        cls.label_type = mommy.make("RelationType", project=cls.project.item)
+        cls.user = cls.project.admin
+
+    def test_can_annotate_relation(self):
+        from_id = mommy.make("Span", example=self.example, start_offset=0, end_offset=1)
+        to_id = mommy.make("Span", example=self.example, start_offset=1, end_offset=2)
+        mommy.make("Relation", example=self.example, from_id=from_id, to_id=to_id)
+
+    def test_cannot_annotate_relation_if_span_example_is_different(self):
+        from_id = mommy.make("Span", example=self.example, start_offset=0, end_offset=1)
+        to_id = mommy.make("Span", start_offset=1, end_offset=2)
+        with self.assertRaises(ValidationError):
+            mommy.make("Relation", example=self.example, from_id=from_id, to_id=to_id)
+
+    def test_cannot_annotate_relation_if_relation_example_is_different_from_span_example(self):
+        from_id = mommy.make("Span", example=self.example, start_offset=0, end_offset=1)
+        to_id = mommy.make("Span", example=self.example, start_offset=1, end_offset=2)
+        with self.assertRaises(ValidationError):
+            mommy.make("Relation", from_id=from_id, to_id=to_id)