http_json.go

// Copyright (c) 2016 Uber Technologies, Inc.

// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package utils

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

// GetJSON makes an HTTP call to the specified URL and parses the returned JSON into `out`.
func GetJSON(url string, out interface{}) error {
	resp, err := http.Get(url)
	if err != nil {
		return err
	}
	return ReadJSON(resp, out)
}

// ReadJSON reads JSON from http.Response and parses it into `out`
func ReadJSON(resp *http.Response, out interface{}) error {
	defer resp.Body.Close()

	if resp.StatusCode >= 400 {
		body, err := ioutil.ReadAll(resp.Body)
		if err != nil {
			return err
		}

		return fmt.Errorf("StatusCode: %d, Body: %s", resp.StatusCode, body)
	}

	if out == nil {
		io.Copy(ioutil.Discard, resp.Body)
		return nil
	}

	decoder := json.NewDecoder(resp.Body)
	return decoder.Decode(out)
}