Converting to json-api extension

Hi , please help me

i want to convert my data to json-api extension using Jaserializer

first , when using generic json i was able to extract the data preload as follows
def render(“user.json”, %{user: user}) do
tags:, &tag_to_json(&1))
User has
name,country, list of tags as associated(include name , maintype , subtype)
Example data
{“data”:[{“tags”:[{“subtype”:“photo”,“name”:“Photo”,“maintype”:“format”}],“name”:“Alberto Giubilini”,“country”:“Singapore”}

now i want it to convert as json_api

the example code given was

attributes [:name, :country]

ive tried
-attributes [:name, :country,:tags]

but still got errors

ive tried

attributes [:name, :country]
has_many :tag,
include: true,
serializer: UserManagementWeb.Tag

but it passes null values