Gorm Primary key can't be created if specify index as well

GORM Playground Link

https://github.com/go-gorm/playground/pull/497

Description

When I do many2many relation, sometimes you want to have additional index other than the one created by primary composite key, e.g. I have

type User struct {} 
type Organization struct {}
type UserOrganization struct {
    UserId         string
    OrganizationId string 
}

by default it create primarily key, e.g. (userId, orgId), but I also want to query by org id, so I need to have an index like:

type UserOrganization struct {
    UserId         string `gorm:"primaryKey,priority=1;`
    OrganizationId string `gorm:"primaryKey,priority=2;index"`
}

but if you do this, from an clean database, it will only create index, not the primary key

the workaround is to just use another composite index, but not really a nice solution

Comment From: a631807682

type UserOrganization struct {
    UserId         string `gorm:"primaryKey;`
    OrganizationId string `gorm:"primaryKey;index"`
}

primaryKey not support priority

Comment From: zfy0701

@a631807682 any particular reason why it can't be supported? we are happy to contribute if it's possible

Comment From: a631807682

@zfy0701 just haven't supported it yet, welcome to contribute it.