One struct with multiple json representations

I developed a library which can help you in this regard: Sheriff

You can annotate your struct fields with special tags and call Sheriff to transform the given struct into a subset of it. After that you can call json.Marshal() or whatever else you want to marshal into.

Your example would become as simple as:

type Community struct {
    Name          string      `json:"name" groups:"trending,detail"`
    Description   string      `json:"description" groups:"trending,detail"`
    Sources       []Source    `json:"sources" groups:"detail"`
    Popularity    int         `json:"popularity" groups:"trending,detail"`
    FavoriteCount int         `json:"favorite_count" groups:"trending,detail"`
    Moderators    []string    `json:"moderators" groups:"detail"`
    Children      []Community `json:"children" groups:"detail"`
    Tracks        []Track     `json:"tracks" groups:"detail"`
}

communities := []Community{
    // communities
}

o := sheriff.Options{
    Groups: []string{"trending"},
}

d, err := sheriff.Marshal(&o, communities)
if err != nil {
    panic(err)
}

out, _ := json.Marshal(d)

[This](http://attilaolah.eu/2014/09/10/json-and-struct-composition-in-go/ ) is a cool approach, which involves creating a sort of Masking struct.

Here's the example in the article:

type User struct {
    Email    string `json:"email"`
    Password string `json:"password"`
    // many more fields…
}

type omit *struct{}

type PublicUser struct {
    *User
    Password omit `json:"password,omitempty"`
}

// when you want to encode your user:
json.Marshal(PublicUser{
    User: user,
})