From e209fa6c07d2a4f5a8296d042ed46c8dee5b30a3 Mon Sep 17 00:00:00 2001
From: Andrew Sisley <a.j.sisley@hotmail.com>
Date: Fri, 4 Oct 2024 10:34:49 -0400
Subject: [PATCH] Handle explicit nil on secondary side relations

---
 internal/db/collection.go                     |  5 +++
 tests/integration/events.go                   |  6 ++++
 .../one_to_one/with_null_value_test.go        | 31 ++++++++++++++++---
 3 files changed, 37 insertions(+), 5 deletions(-)

diff --git a/internal/db/collection.go b/internal/db/collection.go
index dd1a413946..785c96641e 100644
--- a/internal/db/collection.go
+++ b/internal/db/collection.go
@@ -657,6 +657,11 @@ func (c *collection) save(
 
 			relationFieldDescription, isSecondaryRelationID := fieldDescription.GetSecondaryRelationField(c.Definition())
 			if isSecondaryRelationID {
+				if val.Value() == nil {
+					// If the value (relation) is nil, we don't need to check for any documents already linked to it
+					continue
+				}
+
 				primaryId := val.Value().(string)
 
 				err = c.patchPrimaryDoc(
diff --git a/tests/integration/events.go b/tests/integration/events.go
index bf004b99aa..5e57a97294 100644
--- a/tests/integration/events.go
+++ b/tests/integration/events.go
@@ -335,6 +335,12 @@ func getEventsForCreateDoc(s *state, action CreateDoc) map[string]struct{} {
 
 		// check for any secondary relation fields that could publish an event
 		for f, v := range doc.Values() {
+			if v.Value() == nil {
+				// If the new relation value is nil there will be no related document
+				// to get an event for
+				continue
+			}
+
 			field, ok := def.GetFieldByName(f.Name())
 			if !ok {
 				continue // ignore unknown field
diff --git a/tests/integration/mutation/create/field_kinds/one_to_one/with_null_value_test.go b/tests/integration/mutation/create/field_kinds/one_to_one/with_null_value_test.go
index a428f76681..a6421aec5c 100644
--- a/tests/integration/mutation/create/field_kinds/one_to_one/with_null_value_test.go
+++ b/tests/integration/mutation/create/field_kinds/one_to_one/with_null_value_test.go
@@ -13,8 +13,6 @@ package one_to_one
 import (
 	"testing"
 
-	"github.com/stretchr/testify/require"
-
 	testUtils "github.com/sourcenetwork/defradb/tests/integration"
 )
 
@@ -119,10 +117,33 @@ func TestMutationCreateOneToOne_WithExplicitNullOnSecondarySide(t *testing.T) {
 					"published": testUtils.NewDocIndex(0, 0),
 				},
 			},
+			testUtils.Request{
+				Request: `
+					query {
+						Book {
+							name
+							author {
+								name
+							}
+						}
+					}`,
+				Results: map[string]any{
+					"Book": []map[string]any{
+						{
+							"name":   "Secrets at Maple Syrup Farm",
+							"author": nil,
+						},
+						{
+							"name": "How to Be a Canadian",
+							"author": map[string]any{
+								"name": "Will Ferguson",
+							},
+						},
+					},
+				},
+			},
 		},
 	}
 
-	require.Panics(t, func() {
-		testUtils.ExecuteTestCase(t, test)
-	})
+	testUtils.ExecuteTestCase(t, test)
 }