使用golang Viper lib进行高级配置

Question

I'm working on my first real Go project and have been searching for some tools to handle the configuration.

Finally, I've found this tool: https://github.com/spf13/viper which is really nice but I have some issues when I try to handle some more complex configurations such as the following config.yaml example:

app:
  name: "project-name"
  version 1

models:
  modelA:
    varA: "foo"
    varB: "bar"

  modelB:
    varA: "baz"
    varB: "qux"
    varC: "norf"

I don't know how to get the values from modelB for example. While looking at the lib code, I've found the followings but I don't really understand how to use it:

// Marshals the config into a Struct
func Marshal(rawVal interface{}) error {...}

func AllSettings() map[string]interface{} {...}

What I want is to be able, from everywhere in my package, to do something like:

modelsConf := viper.Get("models")
fmt.Println(modelsConf["modelA"]["varA"])

Could someone explain me the best way to achieve this?

Answer 1

Since the "models" block is a map, it's a bit easier to call

m := viper.GetStringMap("models")

m will be a map[string]interface {}

Then, you get the value of m[key], which is an interface {}, so you cast it to map[interface {}]interface {} :

m := v.GetStringMap("models")
mm := m["modelA"].(map[interface{}]interface{})

Now you can access "varA" key passing the key as an interface {} :

mmm := mm[string("varA")]

mmm is foo

Answer 2

You can simply use:

m := viper.Get("models.modelA")

or

newViperForModelA := viper.Sub("models").Sub("modelA")