From d9d5c4dce0dcf322202f3336f5951c844475cc51 Mon Sep 17 00:00:00 2001
From: Mayank Govilla <31316460+mgovilla@users.noreply.github.com>
Date: Sun, 7 Nov 2021 20:47:29 -0500
Subject: [PATCH] Fix self-referential belongs to constraint (#4801)

* create tests for self-ref has one migration

* add relation equality check to avoid skipping self-referential schemas

* remove drop table error check
---
 schema/relationship.go      |  2 +-
 schema/relationship_test.go | 15 +++++++++++++++
 tests/migrate_test.go       | 19 +++++++++++++++++++
 3 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/schema/relationship.go b/schema/relationship.go
index 5699ec5f..c5d3dcad 100644
--- a/schema/relationship.go
+++ b/schema/relationship.go
@@ -519,7 +519,7 @@ func (rel *Relationship) ParseConstraint() *Constraint {
 
 	if rel.Type == BelongsTo {
 		for _, r := range rel.FieldSchema.Relationships.Relations {
-			if r.FieldSchema == rel.Schema && len(rel.References) == len(r.References) {
+			if r != rel && r.FieldSchema == rel.Schema && len(rel.References) == len(r.References) {
 				matched := true
 				for idx, ref := range r.References {
 					if !(rel.References[idx].PrimaryKey == ref.PrimaryKey && rel.References[idx].ForeignKey == ref.ForeignKey &&
diff --git a/schema/relationship_test.go b/schema/relationship_test.go
index cb616fc0..afa103b3 100644
--- a/schema/relationship_test.go
+++ b/schema/relationship_test.go
@@ -93,6 +93,21 @@ func TestBelongsToWithOnlyReferences2(t *testing.T) {
 	})
 }
 
+func TestSelfReferentialBelongsTo(t *testing.T) {
+	type User struct {
+		ID        int32 `gorm:"primaryKey"`
+		Name      string
+		CreatorID *int32
+		Creator   *User
+	}
+
+	checkStructRelation(t, &User{}, Relation{
+		Name: "Creator", Type: schema.BelongsTo, Schema: "User", FieldSchema: "User",
+		References: []Reference{{"ID", "User", "CreatorID", "User", "", false}},
+	})
+
+}
+
 func TestSelfReferentialBelongsToOverrideReferences(t *testing.T) {
 	type User struct {
 		ID        int32 `gorm:"primaryKey"`
diff --git a/tests/migrate_test.go b/tests/migrate_test.go
index 0354e84e..f0467c5b 100644
--- a/tests/migrate_test.go
+++ b/tests/migrate_test.go
@@ -54,6 +54,25 @@ func TestMigrate(t *testing.T) {
 	}
 }
 
+func TestAutoMigrateSelfReferential(t *testing.T) {
+	type MigratePerson struct {
+		ID        uint
+		Name      string
+		ManagerID *uint
+		Manager   *MigratePerson
+	}
+
+	DB.Migrator().DropTable(&MigratePerson{})
+
+	if err := DB.AutoMigrate(&MigratePerson{}); err != nil {
+		t.Fatalf("Failed to auto migrate, but got error %v", err)
+	}
+
+	if !DB.Migrator().HasConstraint("migrate_people", "fk_migrate_people_manager") {
+		t.Fatalf("Failed to find has one constraint between people and managers")
+	}
+}
+
 func TestSmartMigrateColumn(t *testing.T) {
 	fullSupported := map[string]bool{"mysql": true, "postgres": true}[DB.Dialector.Name()]