From 73bc53f061ee1f54b9ef562a3466b5e3c5438aea Mon Sep 17 00:00:00 2001
From: Cr <631807682@qq.com>
Date: Thu, 22 Sep 2022 15:56:32 +0800
Subject: [PATCH] feat: migrator support type aliases (#5627)

* feat: migrator support type aliases

* perf: check type
---
 migrator.go          |  1 +
 migrator/migrator.go | 29 ++++++++++++++++++++++++++---
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/migrator.go b/migrator.go
index 34e888f2..882fc4cc 100644
--- a/migrator.go
+++ b/migrator.go
@@ -68,6 +68,7 @@ type Migrator interface {
 	// Database
 	CurrentDatabase() string
 	FullDataTypeOf(*schema.Field) clause.Expr
+	GetTypeAliases(databaseTypeName string) []string
 
 	// Tables
 	CreateTable(dst ...interface{}) error
diff --git a/migrator/migrator.go b/migrator/migrator.go
index d7ebf276..29c0c00c 100644
--- a/migrator/migrator.go
+++ b/migrator/migrator.go
@@ -408,9 +408,27 @@ func (m Migrator) MigrateColumn(value interface{}, field *schema.Field, columnTy
 
 	alterColumn := false
 
-	// check type
-	if !field.PrimaryKey && !strings.HasPrefix(fullDataType, realDataType) {
-		alterColumn = true
+	if !field.PrimaryKey {
+		// check type
+		var isSameType bool
+		if strings.HasPrefix(fullDataType, realDataType) {
+			isSameType = true
+		}
+
+		// check type aliases
+		if !isSameType {
+			aliases := m.DB.Migrator().GetTypeAliases(realDataType)
+			for _, alias := range aliases {
+				if strings.HasPrefix(fullDataType, alias) {
+					isSameType = true
+					break
+				}
+			}
+		}
+
+		if !isSameType {
+			alterColumn = true
+		}
 	}
 
 	// check size
@@ -863,3 +881,8 @@ func (m Migrator) CurrentTable(stmt *gorm.Statement) interface{} {
 func (m Migrator) GetIndexes(dst interface{}) ([]gorm.Index, error) {
 	return nil, errors.New("not support")
 }
+
+// GetTypeAliases return database type aliases
+func (m Migrator) GetTypeAliases(databaseTypeName string) []string {
+	return nil
+}