https://github.com/nlopes/slack/pull/298#pullrequestreview-116493858

idea1.go

package users

import (
	"encoding/json"
)

// UserProfile contains all the information details of a given user
type UserProfile struct {
	FirstName             string                   `json:"first_name"`
	LastName              string                   `json:"last_name"`
	RealName              string                   `json:"real_name"`
	RealNameNormalized    string                   `json:"real_name_normalized"`
	DisplayName           string                   `json:"display_name"`
	DisplayNameNormalized string                   `json:"display_name_normalized"`
	Email                 string                   `json:"email"`
	Skype                 string                   `json:"skype"`
	Phone                 string                   `json:"phone"`
	Image24               string                   `json:"image_24"`
	Image32               string                   `json:"image_32"`
	Image48               string                   `json:"image_48"`
	Image72               string                   `json:"image_72"`
	Image192              string                   `json:"image_192"`
	ImageOriginal         string                   `json:"image_original"`
	Title                 string                   `json:"title"`
	BotID                 string                   `json:"bot_id,omitempty"`
	ApiAppID              string                   `json:"api_app_id,omitempty"`
	StatusText            string                   `json:"status_text,omitempty"`
	StatusEmoji           string                   `json:"status_emoji,omitempty"`
	Team                  string                   `json:"team"`
	Fields                *UserProfileCustomFields `json:"fields"`
}

type UserProfileCustomFields struct {
	fields map[string]UserProfileCustomField
}

func (fields *UserProfileCustomFields) UnmarshalJSON(b []byte) error {
	if string(b) == "[]" {
		return nil
	}
	if fields.fields == nil {
		fields.fields = map[string]UserProfileCustomField{}
	}
	return json.Unmarshal(b, &fields.fields)
}

func (fields *UserProfileCustomFields) ToMap() map[string]UserProfileCustomField {
	return fields.fields
}

func (profile *UserProfile) FieldsMap() map[string]UserProfileCustomField {
	return profile.Fields.ToMap()
}

// UserProfileCustomField represents a custom user profile field
type UserProfileCustomField struct {
	Value string `json:"value"`
	Alt   string `json:"alt"`
	Label string `json:"label"`
}