Validate if an attribute exists which is a map

[thilak009]

I have the following struct

type QueryRequest struct {
   Input map[string]interface{} `json:"input"`
}

I want to ensure that this field exists always in the request payload for my requests, a simple required was not working

I tried to create a custom validator, like so

func ValidateInputKeyExistence(fl validator.FieldLevel) bool {
	m, ok := fl.Field().Interface().(map[string]interface{})
	if !ok {
		return false
	}
        if _, ok := m["input"]; !ok {
		return false
	}
	return true
}

validator.RegisterValidation("input-payload", ValidateInputKeyExistence)

and change the struct to

type QueryRequest struct {
   Input map[string]interface{} `json:"input" validate:"required,input-payload"`
}

the request body reading code

var data interface{}
err = json.NewDecoder(req.Body).Decode(data)
if err != nil {
....
}
err = validator.Struct(data)

but this is not working, the validator is not being called, i tried adding print statements and see if the validator function is being called.

wasn't able to figure out how to get this working, any help is appreciated 🙏🏻