How to get the ref(id) of my last instance created - faunadb

Question

I don't know how to simply get the ref(id) of my last instance created with faunadb.
I need to put it in an url.
I use this to create my instance:
/* code from functions/todos-create.js */
import faunadb from 'faunadb' /* Import faunaDB sdk */
/* configure faunaDB Client with our secret */
const q = faunadb.query
const client = new faunadb.Client({
secret: process.env.FAUNADB_SECRET
})
/* export our lambda function as named "handler" export */
exports.handler = (event, context, callback) => {
/* parse the string body into a useable JS object */
const eventBody = JSON.stringify(event.body)
const data = JSON.parse(eventBody)
const mission = {
data: JSON.parse(data)
}
// {"title":"What I had for breakfast ..","completed":true}
/* construct the fauna query */
return client.query(q.Create(q.Ref("classes/missions"), mission))
.then((response) => {
console.log("success", response)
/* Success! return the response with statusCode 200 */
return callback(null, {
statusCode: 200,
body: JSON.stringify(response)
})
}).catch((error) => {
console.log("error", error)
/* Error! return the error with statusCode 400 */
return callback(null, {
statusCode: 400,
body: JSON.stringify(error)
})
})
}
I begin to dev, and I need to do this simply with faunadb, can you help me please ?

Answer 1

Instance creation returns a ref, as along with other instance metadata and the user supplied instance data. This means we can compose a select with the create to pull the data out that you require. Using the shell syntax:
Select("ref", Create(Class("missions"), {...})
will yield the ref. Of course if you'd like just the id part of the ref you can drill in further:
Select(["ref", "id"], Create(Class("missions"), {...})