如何在两个 Go 应用程序之间共享略有不同的结构？

Question

I'm facing a big architecture issue in my go project.

1. I have an API that uses structures that come from a MongoDB databases. That means I'm using the database.ObjectID data type in order to store my IDs. For example, here is how I would store an user in the API :

type User struct {
    Id       primitive.ObjectId `bson:"_id,omitempty"`
    Username string
    Tag      int
}

2. The front app is also made in go and uses the same structures because it obviously takes its data from the API. BUT it's not very convenient for the front app to use this primitive.ObjectID data type : the parsing to string is not automatic and it's a bit difficult to manipulate. So from the front point of view, the data structure would more likely look like this :

type User struct {
    Id       string
    Username string
    Tag      int
}

Now in order not to repeat too much code, i would like to re-use those structures from one project to the other with a third party module i would create, without having to write them all twice (one version with string , the other with primitive.ObjectId ).

How can I do ?

Answer 1

Create a new ID type that is equal to interface{} . Then use this ID type, casting to primitive.ObjectID or string when needed. (See example below)

type User struct {
    ID ID `bson:"_id"`
}

type ID = interface{}

func main() {
    u := User{
        ID: primitive.NewObjectID(),
    }

    oid := u.ID.(primitive.ObjectID) // Cast to "primitive.ObjectID"

    fmt.Println(reflect.TypeOf(oid)) // primitive.ObjectID
}