Unable to iterate through the parsed JSON in google go

I am new to go programming, I was trying to parse a JSON file of the following format:

{
  "movies": [
    {
      "name": "Inception",
      "rating": 8.8,
      "genres": [
        "Action",
        "Adventure",
        "Sci-Fi"
      ]
    },
    {
      "name": "Godfather",
      "rating": 9.2,
      "genres": [
        "Crime",
        "Drama"
      ]
    }
  ]
}

Using this code :

package main

import (
  "encoding/json"
  "fmt"
  "io/ioutil"
)

type Movie struct {
  name   string
  rating float64
  genres []string
}

type MovieRating struct {
  movies []Movie
  genre map[string]float64
}

func (mr *MovieRating) init(filename string) {
  var raw interface{}
  data, _ := ioutil.ReadFile(filename)
  _ = json.Unmarshal(data, &raw)
  tmp := raw.(map[string]interface{})["movies"]
  fmt.Println(tmp)
  // now I need to create an array of movies here and assign to mr.movies 
}

func (mr *MovieRating) calculate_rating() {
  fmt.Println("calculating")
}

func main() {
  var mr MovieRating
  mr.init("data.json")
  mr.calculate_rating()
}

But after parsing I have no idea how to iterate through the parsed object. The parsed object is of interface type, How do I parse through this array of movies ?

Unmarshal your Json file against a pointer to slice of movies []Movie , don't use interface{} for that.

One more thing :

> The json package only accesses the exported fields of struct types
> (those that begin with an uppercase letter).

Finally, start here and here.

Edit: this is a working example of unmarshaling an array of movies.