bun:go: how to change `belongs-to` relation mapping field in bun

I am working on bun that has an execting database in PostgreSQL. There was a relationship between the two tables. Order and ResPartner where Order table has a foreign key of ResPartner table having column name contact_partner

type Order struct {
	bun.BaseModel    `bun:"select:sb_order"`
	ID               int64       `bun:"id"`
	GenOid           string      `bun:"gen_oid"`
	ContactPartner   *ResPartner `bun:"rel:belongs-to"`
	ContactPartnerID int64       `bun:"contact_partner"`
}

type ResPartner struct {
	bun.BaseModel `bun:"select:sb_partner"`
	ID            int64  `bun:"id"`
	Name          string `bun:"name"`
}

I try to make queries like this.

err = db.NewSelect().Model(&order).
		Relation("ContactPartner").
		Scan(ctx)

But it is giving error.

reflect: call of reflect.Value.Field on ptr Value

I think bun try to find a field name like contact_partner_id. Is there any way to override the field name?

UPDATE: I have updated my question. see this repo for example: go-db-test

You can map relationships in a bun:go something like:

belongs-to:

 type User struct {
	  ID        int64 `bun:",pk"`
	  Name      string
	  ProfileID int64
	  Profile   *Profile `bun:"rel:belongs-to,join:profile_id=id"`
    }

has-one:

type User struct {
	ID      int64 `bun:",pk"`
	Name    string
	Profile *Profile `bun:"rel:has-one,join:id=user_id"`
}