如何在数据存储区中定义密钥类型？

I have a user kind:

type User struct {
  Username     string
  Email        string
  Password     string
}

And a post kind:

type Post struct {
  User               // how to define here?
  Title        string
  Content      string
}

Post entity looks like:

User: Key(User, '10000')

Title: "some tilte"

Content: "some content"

How can define Post.User?

Since your Post entities contain complete Keys, use datastore.Key as the field type:

type Post struct {
    User    *datastore.Key
    Title   string
    Content string
}