Mailchimp API returning a large gzip object when using node-fetch rather than json

Question

I am trying to return a list of changed members from the mailchimp API, which returns the following (correct) json if I use curl/Postman:

{
  "members": [
    {
      "id": "187fhdy650b10e8d43552b6c3672368212",
      "email_address": "example@email.co.uk",
      "unique_email_id": "2edbhgy73836",
      "email_type": "html",
      "status": "unsubscribed",
      "merge_fields": {
        "FNAME": "",
        "LNAME": "",
        "MMERGE5": "",
        //etc....

I want to return this object using a Node application, so am using node-fetch as follows:

fetch(`https://us5.api.mailchimp.com/3.0/lists/<listid>/members?since_last_changed=2016-10-18T23:10:18+00:00`, {headers: authHeader})
  .then((response) => {
    if (response.ok) {
      res.status(response.status).send(response)
    } else {
      res.status(response.status).send(response)
    }
  }).catch((error) => {
      res.status(500).send(error.message)
  })})

This returns a completely different json structure, which to me suggests it is mid-way through receiving the data and the fetch promise shouldn't have resolved. It's quite large, so I'm including what I see as the key bits of information:

{
  "_opts": {},
  "_chunkSize": 16384,
  "_readableState": {
"objectMode": false,
"highWaterMark": 16384,
"buffer": [],
"length": 0,
"pipes": null,
"pipesCount": 0,
"flowing": null,
"ended": false,
"endEmitted": false,
"reading": false,
"sync": false,
"needReadable": true,
"emittedReadable": false,
"readableListening": false,
"resumeScheduled": false,
"defaultEncoding": "utf8",
"ranOut": false,
"awaitDrain": 0,
"readingMore": false,
"decoder": null,
"encoding": null
},
"readable": true,
"domain": null,
"_events": {
"end": [
  null,
  null
]
},
"_eventsCount": 7,
"_writableState": {
  "objectMode": false,
  "highWaterMark": 16384,
  "needDrain": false,
  "ending": true,
  "ended": true,
  "finished": false,
  "decodeStrings": true,
  "defaultEncoding": "utf8",
  "length": 2674,
  "writing": true,
  "corked": 0,
  "sync": false,
  "bufferProcessing": false,
  "writelen": 2674,
  "bufferedRequest": null,
  "lastBufferedRequest": null,
  "pendingcb": 1,
  "prefinished": false,
  "errorEmitted": false,
  "bufferedRequestCount": 0,
  "corkedRequestsFree": {
  "next": null,
  "entry": null
  }
},
"writable": false,
"allowHalfOpen": true,
"_transformState": {
 "needTransform": false,
 "transforming": true,
 "writechunk": {
  "type": "Buffer",
  "data": [
    31,
    139,
    8,
    0,
    0,
    0,
    0,
    0,
    198,....

I've tried parsing this in different ways, such as reading the reponse first:

.then((response) => {
  response.text()})
.then((response) => {
  res.status(200).send(response)
})

which returns an undefined object. And also parsing as json:

.then((response) => {
  res.status(200).send(response.json())
})

which returns an empty object {}

Is there anything more I can try with my fetch call?

Answer 1

fetch() returns a promise that resolves to a response object, which in turn has various methods ( .text() , .json() ) that return promises that resolve to the body of the response.

So try this:

fetch(`https://us5.api.mailchimp.com/3.0/lists/<listid>/members?since_last_changed=2016-10-18T23:10:18+00:00`, {headers: authHeader})
  .then(response => {
    res.status(response.status);
    return response.json();
  }).then(body => {
    res.send(body);
  }).catch(error => {
    res.status(500).send(error.message)
  });