Loading json config files in golang, useful for database type configs.

configloader.go

/*
layout of config file
{
  "host":"localhost",
  "port": 5432,
  "user": "postgres",
  "password": "123123",
  "database": "example_db"
}

*/
package main

type Config struct {
	Host     string `json:"host"`
	Port     int    `json:"port"`
	User     string `json:"user"`
	Password string `json:"password"`
	Database string `json:"database"`
}

func (c Config) String() string {
	return fmt.Sprintf("%s, %d, %s, %s", c.Host, c.Port, c.User, c.Database)
}

func NewConfig(filename string) (Config, error) {
	var cf Config
	confFile, err := os.Open("./" + filename) // if the file is in the same directory
	defer confFile.Close()

	if err != nil {
		return cf, err
	}
	jsonParser := json.NewDecoder(confFile)
	jsonParser.Decode(&cf)
	if err != nil {
		return cf, err
	}

	return cf, nil
}

func main() {
  	var cfg, err = NewConfig("config.json")
	fmt.Println(err) // prints nil
	fmt.Println(cfg) // prints the objects String() method.
}