From 477fb71180abee3e3326b5a94331309f6cf24a3a Mon Sep 17 00:00:00 2001
From: jasonchuan <jason_chuan@qq.com>
Date: Sun, 4 Feb 2024 17:22:41 +0800
Subject: [PATCH] Revert "refactor: distinguish between Unique and UniqueIndex
 (#195)"

This reverts commit 1cfbc8652cd8c56d1cd05c1a3e111318b3dd551d.
---
 migrator.go | 57 +++++++++++++++++++++++++++++++----------------------
 1 file changed, 33 insertions(+), 24 deletions(-)

diff --git a/migrator.go b/migrator.go
index 6c58a5f..c085a70 100644
--- a/migrator.go
+++ b/migrator.go
@@ -13,28 +13,25 @@ import (
 	"gorm.io/gorm/schema"
 )
 
-// See https://stackoverflow.com/questions/2204058/list-columns-with-indexes-in-postgresql
-// Here are some changes:
-// - use `LEFT JOIN` instead of `CROSS JOIN`
-// - exclude indexes used to support constraints (they are auto-generated)
 const indexSql = `
-SELECT
-	ct.relname AS table_name,
-	ci.relname AS index_name,
-	i.indisunique AS non_unique,
-	i.indisprimary AS primary,
-	a.attname AS column_name
-FROM
-	pg_index i
-	LEFT JOIN pg_class ct ON ct.oid = i.indrelid
-	LEFT JOIN pg_class ci ON ci.oid = i.indexrelid
-	LEFT JOIN pg_attribute a ON a.attrelid = ct.oid
-	LEFT JOIN pg_constraint con ON con.conindid = i.indexrelid
-WHERE
-	a.attnum = ANY(i.indkey)
-	AND con.oid IS NULL
-	AND ct.relkind = 'r'
-	AND ct.relname = ?
+select
+    t.relname as table_name,
+    i.relname as index_name,
+    a.attname as column_name,
+    ix.indisunique as non_unique,
+	ix.indisprimary as primary
+from
+    pg_class t,
+    pg_class i,
+    pg_index ix,
+    pg_attribute a
+where
+    t.oid = ix.indrelid
+    and i.oid = ix.indexrelid
+    and a.attrelid = t.oid
+    and a.attnum = ANY(ix.indkey)
+    and t.relkind = 'r'
+    and t.relname = ?
 `
 
 var typeAliasMap = map[string][]string{
@@ -350,6 +347,16 @@ func (m Migrator) AlterColumn(value interface{}, field string) error {
 					}
 				}
 
+				if uniq, _ := fieldColumnType.Unique(); !uniq && field.Unique {
+					idxName := clause.Column{Name: m.DB.Config.NamingStrategy.IndexName(stmt.Table, field.DBName)}
+					// Not a unique constraint but a unique index
+					if !m.HasIndex(stmt.Table, idxName.Name) {
+						if err := m.DB.Exec("ALTER TABLE ? ADD CONSTRAINT ? UNIQUE(?)", m.CurrentTable(stmt), idxName, clause.Column{Name: field.DBName}).Error; err != nil {
+							return err
+						}
+					}
+				}
+
 				if v, ok := fieldColumnType.DefaultValue(); (field.DefaultValueInterface == nil && ok) || v != field.DefaultValue {
 					if field.HasDefaultValue && (field.DefaultValueInterface != nil || field.DefaultValue != "") {
 						if field.DefaultValueInterface != nil {
@@ -408,11 +415,13 @@ func (m Migrator) modifyColumn(stmt *gorm.Statement, field *schema.Field, target
 func (m Migrator) HasConstraint(value interface{}, name string) bool {
 	var count int64
 	m.RunWithValue(value, func(stmt *gorm.Statement) error {
-		constraint, table := m.GuessConstraintInterfaceAndTable(stmt, name)
+		constraint, chk, table := m.GuessConstraintAndTable(stmt, name)
+		currentSchema, curTable := m.CurrentSchema(stmt, table)
 		if constraint != nil {
-			name = constraint.GetName()
+			name = constraint.Name
+		} else if chk != nil {
+			name = chk.Name
 		}
-		currentSchema, curTable := m.CurrentSchema(stmt, table)
 
 		return m.DB.Raw(
 			"SELECT count(*) FROM INFORMATION_SCHEMA.table_constraints WHERE table_schema = ? AND table_name = ? AND constraint_name = ?",