Writing and reading json in Go (Golang)

So, say I have some articles in JSON.

{"articles": [{"title": "This is an awesome post.", "content": "How amazing is this article actually?"}, {"title": "Asking a question on StackOerflow", "content": "It's very easy."}]}

So I want to read the articles in their order i.e. This is an awesome post, then Asking a question on StackOverflow. Then I have to edit or write to them in order, so when I have a new post it will be:

{"articles": [{"title": "New Post", "content": "Content"},{"title": "This is an awesome post.", "content": "How amazing is this article actually?"}, {"title": "Asking a question on StackOerflow", "content": "It's very easy."}]}

Or updating:

{"articles": [{"title": "New Post", "content": "Content of new post"},{"title": "This is an awesome post.", "content": "How amazing is this article actually?"}, {"title": "Asking a question on StackOerflow", "content": "It's very easy."}]}

I intend to manipulate articles by their titles, but I haven't been able to get such manipulation in Go (the writing and updating). Can you help me out?

I have been able to get reading with 2 interfaces, but I don't know how to write, update.

type Articles struct {
	Article []Article
}

type Article struct {
	Title   string
	Content string
}

Here's another approach: http://play.golang.org/p/K-eYSrn1tx

I'll copy the code here for easy of viewing:

package main

import (
	"encoding/json"
	"fmt"
)

type JsonDoc struct {
	Articles []Article
}

type Article struct {
	Title   string
	Content string
}

func main() {
	s := `{"articles": [
	{"title": "This is an awesome post.", 
	 "content": "How amazing is this article actually?"}, 
	{"title": "Asking a question on StackOverflow",
	 "content": "It's very easy."}]}`

	doc := JsonDoc{}
	// Toy example.  In a real application, we should not ignore
	// the possibility of an error here.
	json.Unmarshal([]byte(s), &doc)

	fmt.Printf("Before: %#v\n", doc)

	// Note: adding to the front of a slice is a bit expensive.
	// Consider adding to the back, or use a data representation
	// that's more appropriate.
	frontArticle := Article{Title: "Another article",
		Content: "Here's its content."}
	doc.Articles = append([]Article{frontArticle},
		doc.Articles...)

	fmt.Printf("After: %#v\n", doc)

	// Toy example: in a real application, we should not ignore
	// the possibility of an error here.
	marshalled, _ := json.Marshal(&doc)
	fmt.Printf("%s\n", marshalled)
}

You'll notice that the marshalled output is slightly different from the input in terms of the key names. The input used lowercased keys, but our output is producing uppercased keys! You'll need to tell the JSON encoder a bit more about the external representation so it can do the right thing at marshal time. Here's one way to do it, using struct field tags: http://play.golang.org/p/HHeMQUcCDV

Ok, I've solved it:

	s := `{"articles": [{"title": "This is an awesome post.", "content": "How amazing is this article actually?"}, {"title": "Asking a question on StackOverflow", "content": "It's very easy."}]}`
	items := &Articles{}
	json.Unmarshal([]byte(s), items)
	theLength := len(items.Article) + 1
	newArray := make([]Article, theLength)
	newArray[0] = Article{"My New Title", "My New Content"}
	for i := 1; i < theLength; i++ {
		newArray[i] = items.Article[i-1]
	}
	newItems := &Articles{}
	newItems.Article = newArray
	//now newItems is the new interface