Custom errors JSON output with Factory

It is possible to use the MarshalJsonFunc parameter of Factory for customizing the JSON output for errors.

customMarshalJson := func(e *Error) ([]byte, error) {

  errors := map[string]interface{}{}

  for k, v := range e.errors {
    errors[k] = v.Messages()
  }

  // Add a root key level called errors, which is not set by default in the Valgo implementation.
  return json.Marshal(map[string]map[string]interface{}{"errors": errors})
}

// Set the custom Marshal JSON function
factory := v.Factory(v.FactoryOptions{
  MarshalJsonFunc: customMarshalJson
})

// Now validate something to check if the output JSON contains the errors root key

val := factory.Is(v.String("", "name").Not().Empty())

out, _ := json.MarshalIndent(val.Error(), "", "  ")
fmt.Println(string(out))

output:

{
  "errors": {
    "name": [
      "Name can't be empty"
    ]
  }
}