struct golang字段中的额外值

Question

What does this "extra" field gorm:"primary_key" do when creating a struct?

type Model struct {
    ID        uint `gorm:"primary_key"`
    CreatedAt time.Time
    UpdatedAt time.Time
    DeletedAt *time.Time
}

Answer 1

It's a tag used by the gorm package to let the package know that the field will be used as a primary key

See https://github.com/jinzhu/gorm/blob/b9a39be9c5e77bb0bfebd516114a8a4d605c645a/model_struct.go#L135-L139

gormSettings := parseTagSetting(field.Tag.Get("gorm"))
if _, ok := gormSettings["PRIMARY_KEY"]; ok {
    field.IsPrimaryKey = true
    modelStruct.PrimaryFields = append(modelStruct.PrimaryFields, field)
}