Read config using a struct

[spy16]

Is there a way to directly register a struct with viper and read configs appropriately ?

Something like demonstrated below:

type config struct {
   Host string
   Port int
   Database database
}

type database struct {
   Host string
   Port int
}

cfg := config{
     Host: "localhost",
     Port: 8080,
}
viper.AutomaticEnv()
viper.SetConfigName("app")
viper.ReadInConfig()
viper.Unmarshal(&cfg)

I know Unmarshal exists but it doesn't do what i was expecting. My expectation for the above snippet was that, after the Unmarshal call, following would be true:

1. cfg.Host would be mapped to HOST env var, or host key in app.yaml or app.json etc.
2. cfg.Database.Host would be mapped to DATABASE_HOST env var, database_host key in app.yaml or app.json etc (or host sub-key of database key in these files)
3. Non-zero values given to the fields will be used as defaults if an overriding value not found in any config source (i.e., env var, yaml files, json files etc.)

Why?

One of the projects i am working which is using viper has has large set of configuration options. It is becoming tedious to add viper.GetString("config_name") for every single config and then populate the config struct. If the above expectations were true, we could simply compose configs of different structs into one config struct and call Unmarshal with that struct.

[Nicolab]

I have the same, you are found a solution?

[sagikazarmark]

Looks like a duplicate of #584

See my comment: #584 (comment)

TL;DR Unmarshal doesn't work with AutomaticEnv.

[Nicolab]

Thanks

[spy16]

Okay thanks @sagikazarmark . Will close this in favor of discussion on #584.