How to iterate over yml sections with structs? - go

Question

I use viper. I'm trying to get info from structs with yml-config.
type Config struct {
Account User `mapstructure:"user"`
}
type User struct {
Name string `mapstructure:"name"`
Contacts []Contact `mapstructure:"contact"`
}
type Contact struct {
Type string `mapstructure:"type"`
Value string `mapstructure:"value"`
}
func Init() *Config {
conf := new(Config)
viper.SetConfigType("yaml")
viper.ReadInConfig()
...
viper.Unmarshal(conf)
return conf
}
...
config := Init()
...
for _, contact := range config.Account.Contacts {
type := contact.type
vlaue := contact.value
}
And config.yml
user:
name: John
contacts:
email:
type: email
value: test#test.com
skype:
type: skype
value: skypeacc
Can I get structure items like this? I could not get contact data like that. Is it possible?

Answer 1

If I'm getting right what you want to achieve, and based on the for loop you provided;
What you actually need is a YAML sequence, which is an array. So your final YAML file should look like;
user:
name: John
contacts:
- type: email
value: test#test.com
- type: skype
value: skypeacc
- type: email
value: joe#example.com
Also, you have a typo in your tag on Contacts slice. It should match the YAML key;
type User struct {
Name string `mapstructure:"name"`
Contacts []Contact `mapstructure:"contacts"`
}
If you wish to keep the original YAML file structure you have to provide a tag (and the corresponding struct field) for each YAML key, so looping over it wouldn't be possible out of the box, because email and skype are parsed as struct fields. An example of the struct for the original YAML file would be;
type Config struct {
Account User `mapstructure:"user"`
}
type User struct {
Name string `mapstructure:"name"`
Contacts Contacts `mapstructure:"contacts"`
}
type Contacts struct {
Email Contact `mapstructure:"email"`
Skype Contact `mapstructure:"skype"`
}
type Contact struct {
Type string `mapstructure:"type"`
Value string `mapstructure:"value"`
}

Answer 2

I think the only significant problem is that in your data structures you've declared Contacts as a list, but in your YAML file it's a dictionary. If you structure your input file like this:
user:
name: John
contacts:
- type: email
value: test#test.com
- type: skype
value: skypeacc
Then you can read it like this:
package main
import (
"fmt"
"github.com/spf13/viper"
)
type Config struct {
User User
}
type User struct {
Name string
Contacts []Contact
}
type Contact struct {
Type string
Value string
}
func main() {
var cfg Config
viper.SetConfigName("config")
viper.AddConfigPath(".")
err := viper.ReadInConfig()
if err != nil {
panic(err)
}
viper.Unmarshal(&cfg)
fmt.Println("user: ", cfg.User.Name)
for _, contact := range cfg.User.Contacts {
fmt.Println(" ", contact.Type, ": ", contact.Value)
}
}
The above code is runnable as-is; you should just be able to drop it
into a file and build it. When I run the above example, I get as
output:
user: John
email : test#test.com
skype : skypeacc