Add steps to return error if duplicate in list

backend/metagenedb/apps/catalog/serializers/bulk_list.py

 from rest_framework import serializers
-from rest_framework.exceptions import ValidationError
+from rest_framework.exceptions import ValidationError, ErrorDetail
 from rest_framework.fields import SkipField
 from rest_framework.settings import api_settings
 from rest_framework.utils import html, model_meta
@@ -68,6 +68,7 @@ class BulkListSerializer(serializers.ListSerializer):
 
         ret = []
         errors = []
+        primary_keys = set()
         for item in data:
             try:
                 if isinstance(self.instance, dict):
@@ -75,6 +76,10 @@ class BulkListSerializer(serializers.ListSerializer):
                     validated = self.child.run_validation(item)
                 else:
                     validated = self.child.run_validation(item)
+                if item[lookup_field] not in primary_keys:
+                    primary_keys.add(item[lookup_field])
+                else:
+                    errors.append(ErrorDetail(item[lookup_field], code='duplicate'))
             except ValidationError as exc:
                 errors.append(exc.detail)
             else:

backend/metagenedb/apps/catalog/serializers/test_bulk_list.py

@@ -3,6 +3,7 @@ from unittest import TestCase
 from unittest.mock import Mock
 
 from rest_framework.test import APITestCase
+from rest_framework.exceptions import ValidationError
 
 from metagenedb.apps.catalog.serializers import FunctionSerializer
 from metagenedb.apps.catalog.serializers.bulk_list import BulkListSerializer
@@ -140,3 +141,26 @@ class TestOperationsBulk(APITestCase):
         self.assertEqual(self.function_api.get_all()['count'], 2)
         for data in validated_data:
             self.assertDictEqual(self.function_api.get(data['function_id']), data)
+
+    def test_to_internal_value_duplicate(self):
+        functions = FunctionFactory.build_batch(2)
+        data = [
+            {
+                "function_id": functions[0].function_id,
+                "source": functions[0].source,
+                "name": "Test 1"
+            },
+            {
+                "function_id": functions[0].function_id,
+                "source": functions[0].source,
+                "name": "Test 1"
+            },
+            {
+                "function_id": functions[1].function_id,
+                "source": functions[1].source,
+                "name": "Test 2"
+            }
+        ]
+        serializer = FunctionSerializer(many=True)
+        with self.assertRaises(ValidationError):
+            serializer.to_internal_value(data)