与Golang的JSON的SQL关系

Question

Still learning Go.

If I have a posts and comments table relationship in a mysqp/pg database eg

Post  id, title
Comments  id, post_id, comment

I'd like to have a json representation of this:

{
  id: 1
  title: "A blog post"
  comments: [
      {id: 1, comment: "This is comment 1"},
      {id: 2, comment: "This is comment 2"}
  ]
}

I am able to grab the posts and show the json, just not the comments. I think I need to have an array of Comment structs in the Post struct. Just not sure how to tie it all together, particularly the scanning of the rows.

An example showing outputting json from a relationship like this would be great.

Answer 1

It just so happens I wrote an example for someone recently.

https://gist.github.com/freeeve/9167240

The meat is in here, replace Post with Message and Comments with Friends:

msgs := []Message{}
for rows.Next() {
    msg := Message{}
    friend := Friend{}
    err := rows.Scan(&msg.Id, &msg.Name, &msg.Street, &msg.City, &msg.Zip, &msg.State, &msg.Email, &msg.Phone, &friend.Id, &friend.Name)
    if err != nil {
        log.Fatal(err)
    }
    if len(msgs) == 0 || msgs[len(msgs)-1].Id != msg.Id {
        msg.Friends = append(msg.Friends, friend)
        msgs = append(msgs, msg)
    } else {
        msgs[len(msgs)-1].Friends = append(msgs[len(msgs)-1].Friends, friend)
    }
}