Graphql Nested (join) question

I i don’t find howto or documents for meteor with graphql so i create example wit create --apollo.

I try to return query from 2 source 1 is postegres and 2 is mongo

postgres have this tabke fondi


1 Gigi Gigi Sw2WTj8chR2ycYgXn
2 giorgio giorgio 7eaSWAWqA5WmTDpJb

and mongo have this document

“_id”: “Sw2WTj8chR2ycYgXn”,
“title”: “Do the Tutorial”,
“url”: “Meteor”,
“createdAt”: {
“$date”: “2021-04-17T12:27:49.373Z”

i write this schema:

`type Link {
    _id: ID!
    title: String
    url: String

type Fondi {
    id: ID!
    nome: String
    descrizione: String
    link_id: String
    link: Link

type Query {
    link (link_id: ID!): Link
    link_id (link_id: ID!): Link
    links: [Link]
    fondi: [Fondi]

and this is my resolver

const resolvers = {
  Query: {
    link: (Object,{link_id}) => {
      return LinksCollection.findOne({_id:link_id})},
    link_id: (Object,{link_id}) => {
      return LinksCollection.findOne({_id:link_id})},
    links: () => LinksCollection.find().fetch(),
    fondi: () =>{

but when a try to execute this query:

query {
  fondi {
    link {

the link is null, this is my result:

  "data": {
    "fondi": [
        "nome": "Gigi",
        "descrizione": "Gigi",
        "link_id": "Sw2WTj8chR2ycYgXn",
        "link": null
        "nome": "giorgio",
        "descrizione": "giorgio",
        "link_id": "7eaSWAWqA5WmTDpJb",
        "link": null

i think link is attrubute of fondi and is a function so execute resolver function but nothing

Have any suggestion or webpages i can read?

Thank you in advance

I have found a solutions! Thank you anyway