viperEx

Filling the gaps from the awesome spf13/viper project.
There is an spf13/viper--issue that reference this project.

The Gaps

Asp.Net core allows for deep updating a configuration via an opinionated pathing ENV variable.

Given a configuration structs below;

type Nest struct {
  Name       string
  CountInt   int
  CountInt16 int16
  Eggs       []Egg
}

type NestedMap struct {
  Eggs map[string]Egg
}

type ValueContainer struct {
  Value interface{}
}

func (vc *ValueContainer) GetString() (string, bool) {
  value, ok := vc.Value.(string)
  return value, ok
}

type Egg struct {
  Weight      int32
  SomeValues  []ValueContainer
  SomeStrings []string
}
type Settings struct {
  Name string
  Nest *Nest
}

type SettingsWithNestedMap struct {
  Name      string
  NestedMap *NestedMap
}

I would like to surgically update a value deep in the tree.
I want it to dig down and enter into the right array or map object and keep going.

Arrays

Here I would like to change value of Value, which is in the 2nd object in the SomeValues array, which is in an Egg object which is in the 2nd object in the Eggs array, which is inside or the nest object. Phewww!

nest__Eggs__1__SomeValues__1__Value=3

Here it accounts for arrays, where Eggs is an array. The Egg stuct also contains an array

  os.Setenv("APPLICATION_ENVIRONMENT", "Test")
  os.Setenv("nest__Eggs__1__Weight", "5555")
  os.Setenv("nest__Eggs__1__SomeValues__1__Value", "Heidi") // update an item in a struct
  os.Setenv("nest__Eggs__1__SomeStrings__1", "Zep") // SomeStrings is a []string, so this is the convention for directly modifying a primitive in an array

  allSettings := myViper.AllSettings() // normal viper stuff

  myViperEx, err := New(allSettings, func(ve *ViperEx) error {
    ve.KeyDelimiter = "__"
    return nil
  })
  myViperEx.UpdateFromEnv()

  // or individually
  myViperEx.UpdateDeepPath("nest__Eggs__0__Weight", 1234)
  myViperEx.UpdateDeepPath("nest__Eggs__0__SomeValues__1__Value", "abcd")
  myViperEx.UpdateDeepPath("nest__Eggs__0__SomeStrings__1", "abcd")

  // since we took ownership of the all settings we need to use our own Unmarshal
  err = myViperEx.Unmarshal(&settings)

Maps

Maps are very similar to arrys, except that a string is used instead of a num for pathing.

Array pathing

nest__Eggs__1__SomeValues__1__Value=3

vs.

Map pathing

nest__Eggs__bob__SomeValues__1__Value=3