Processing a JSON API Response

Working on my first Go project and I'm having some trouble wrapping my mind around some of the complex data structures. At the moment, I'm mocking up the response from an API that will return a JSON object containing 2 properties:

• columns contains an array of fields in the order they should be handled
• data contains an array of objects containing the properties listed in columns

I need to iterate over the data array/slice and, within that, iterate over the columns array/slice and extract the current property from the current data object. I'm not handling the data structure properly. A lot of trial and error has left me with the following code and enough frustration to decide I simply needed to ask the question.

res, err := http.Get("http://roadmap-proto.robwilkerson.org/demo.json")
failOnError(err, "Uh oh")
defer res.Body.Close()

// Decode and process the JSON response
// var v map[string]interface{}
type View struct {
	Columns []string               `"json:columns"`
	Data    map[string]interface{} `"json:data"`
}
v := View{}
json.NewDecoder(res.Body).Decode(&v)
log.Printf("[====>] Data: %s", v)

The output from log.Printf() is this:

Data: {[id avatar name email phone address] map[]}

The columns seems to read okay, but not the data. Ultimately I need to loop over that and write each field to an Excel cell, but so far I can't even get the data to "load" properly.

Any push in the right direction would be much appreciated.

UPDATE

I inadvertently omitted some key info: On any given call to the API, the number and names of the columns may be different. Within a given call, all objects in the data array will be the same, but each call could be very, very different. I can't define a static struct and have that work.

I would use two structs for this:

type ColData struct {
	Id      string `json:"id"`
	Avatar  string `json:"avatar"`
	Name    string `json:"name"`
	Email   string `json:"email"`
	Phone   string `json:"phone"`
	Address string `json:"address"`
}

type View struct {
	Columns []string  `json:"columns"`
	Data    []ColData `json:"data"`
}

In response to your update:

type View struct {
	Columns []string               `"json:columns"`
	Data    map[string]interface{} `"json:data"`
}

just needs to become

type View struct {
	Columns []string               `"json:columns"`
	Data    []map[string]interface{} `"json:data"`
}

to get your data into the struct. Might also be nice to just work with them as string or json.RawMessage instead of an interface{} as well, but I don't really know what you're doing with it/what you could possibly get out.