GraphCool TypeError: Converting circular structure to JSON - api

Question

I copy-pasted example from official documentation in hope that I will see some different error (invalid URL or invalid auth key or something similar) However I get some webpack/sandbox error:
const fetch = require('isomorphic-fetch')
const Base64 = require('Base64')
const FormData =require('form-data')
const apiKey = '__MAILGUN_API_KEY__'
const url = '__MAILGUN_URL__'
export default event => {
const form = new FormData()
form.append('from', 'Nilan <nilan#graph.cool>')
form.append('to', 'Nikolas <nikolas#graph.cool>')
form.append('subject', 'Test')
form.append('text', 'Hi')
return fetch(url, {
headers: {
'Authorization': `Basic ${Base64.btoa(apiKey)}`
},
method: 'POST',
body: form
})
}
Even simple API requests fail:
require('isomorphic-fetch')
module.exports = function (event) {
const url = 'https://jsonplaceholder.typicode.com/posts'
return fetch(url)
}
The code above also returns:
TypeError: Converting circular structure to JSON
at Object.stringify (native)
at /data/sandbox/lib/sandbox.js:532:48
at /data/io/8e0059b3-daeb-4989-972f-e0d88e27d15e/webtask.js:46:33
at process._tickDomainCallback (node.js:481:9)
How do I successfully call API from custom graphcool subscription/resolver?

Answer 1

This is the simplest working example:
require('isomorphic-fetch')
module.exports = function (event) {
const url = 'https://jsonplaceholder.typicode.com/posts'
return fetch(url)
.then(res => res.json())
.then(data => {
console.log(data)
return {
data: {
sum: 3
}
}
})
}