MUL unique index always causes field migration

[Nomango]

GORM Playground Link

No time to make it for now.

Description

Similar to #5950, the reason is field migration is checking field.Unique in this line:

gorm/migrator/migrator.go

Line 481 in 7da24d1

if unique, ok := columnType.Unique(); ok && unique != field.Unique {

For mysql environment, columnType.Unique is only true when column_key is equal to UNI.

https://github.com/go-gorm/mysql/blob/7746e77af41571f61e6154eccd46dce1c6da0a1d/migrator.go#L222

But composite indexes' column_key is MUL. Therefore it always causes field migration.

[github-actions]

The issue has been automatically marked as stale as it missing playground pull request link, which is important to help others understand your issue effectively and make sure the issue hasn't been fixed on latest master, checkout https://github.com/go-gorm/playground for details. it will be closed in 30 days if no further activity occurs. if you are asking question, please use the Question template, most likely your question already answered https://github.com/go-gorm/gorm/issues or described in the document https://gorm.io ✨ Search Before Asking ✨

[Nomango]

It seems that it cannot be reproduced.

[Nomango]

Since the merger last week this issue has come up again.

Should field.Unique be true if the field has a MUL unique index?

[github-actions]

The issue has been automatically marked as stale as it missing playground pull request link, which is important to help others understand your issue effectively and make sure the issue hasn't been fixed on latest master, checkout https://github.com/go-gorm/playground for details. it will be closed in 30 days if no further activity occurs. if you are asking question, please use the Question template, most likely your question already answered https://github.com/go-gorm/gorm/issues or described in the document https://gorm.io ✨ Search Before Asking ✨