Gorm Preload convert key reference to string/integer

Question

I am using Gorm and DB driver PostgreSQL and i have struct like this :

Projects

type Project struct {
    ID              int       
    ListingOrigin         *ListingOrigin `gorm:"foreignkey:ListingID"`
}

func (Project) TableName() string {
    return "project.projects"
}

ListingOrigin

type ListingOrigin struct {
    ID int 
    ListingID string   `gorm:"not null"`
    OriginID  uint     `gorm:"not null"`
    Project   *Project `gorm:"foreignKey:ListingID;references:id"`
}

func (l *ListingOrigin) TableName() string {
    return "listing_origins"
}

As u can see we can do Preload using ID on table Project, but first, I need to convert that value to string or integer.

When I do like this :

    func (r *ProjectRepository) Options() (result []model.Project, err error) {
    var projects []model.Project
    query := r.db.Model(projects).Preload("ListingOrigin")

    query.Order("name asc")

    err = query.Find(&projects).Error

    if err != nil {
        return nil, err
    }

    return projects, nil
}

the error occurred :

ERROR: operator does not exist: character varying = integer (SQLSTATE 42883) [rows:0] SELECT * FROM "listing_origins" WHERE "listing_origins"."listing_id" IN (1,3,4) AND "listing_origins"."deleted_at" IS NULL

Is there any way to do this ?