fetch failed from companion to web server

[junggu_choi]

Hi,

I made sideload app and I want to send my data(json type) to a web server.

But When I run the app, it simply prints "request failed" and no error message is displayed.

In the code below, I would like to ask you the wrong part or advice.

p.s. posted_data is json type data.

import * as messaging from "messaging";


// Listen for the onmessage event
messaging.peerSocket.onmessage = function(evt) {
  // Output the message to the console
  console.log("Received from device... "+JSON.stringify(evt.data));
  var posted_data = JSON.stringify(evt.data);
  
  console.log(posted_data);
  
  fetch("https://localhost:2002/index.html", {
    method: 'post',
    headers: {
      "Content-type": "application/x-www-form-urlencoded; charset=UTF-8"
    },
    body: posted_data
  })
  //.then(posted_data)
  .then(function (posted_data) {
    console.log('Request succeeded with JSON response', posted_data);
  })
  .catch(function (error) {
    console.log('Request failed', error);
  });
};

[philvms]

try:

'Content-Type': 'application/json'

thats what I use after I stringified my JSON data like you did.

if that doesn't work you can try http request since it is on the localhost and you don't need https. This removes a source of error as maybe the authentication might fail. Also you can remove another source of error by using Postman to test your server for the FETCH API without the fitbit app. That way you can determine if its your fitbit code or your server code.

Also it may or may not be case sensitive:

method: 'post',

should be

method: 'POST',

[junggu_choi]

Thank you for your reply!

I tried to change code to 'Content-Type': 'application/json' and remove 'https:'.

And I re-execute my code but, I checked same error..

So, I changed my code more simply.

import * as messaging from "messaging";


// Listen for the onmessage event
messaging.peerSocket.onmessage = function(evt) {
  // Output the message to the console
  //console.log("Received from device... "+JSON.stringify(evt.data));
  var posted_data = JSON.stringify(evt.data);
  
  console.log(posted_data);
  
  const obj = {
  method: 'POST',
  headers: 'myHeaders',
  mode: 'cors',
  cache: 'default',
  body: posted_data
  }
  fetch('http://localhost:2002/index.html', obj)
  .then(res => res => res.json())
  .then(json => console.log(json))
  .catch(err => console.log(err));
};

Now, I get a error message

'TypeError: Failed to execute 'fetch' on 'Window': The provided value is not of type '(sequence<sequence<ByteString>> or record<ByteString, ByteString>)''.

In fact, it is the first time to create a web.

If I post to the url using the fetch function, how does it react to the index.html file of the web page I created?

[philvms]

headers: 'myHeaders',

you are assigning headers the string 'myHeaders' which means nothing to the fetch API. Take the quotes away.

This is my code. Give it a shot. Find what your local IP is for your server and replace it with mine.

    fetch('http://127.0.0.1:8100', {
      method: 'POST',
      headers:{'Content-Type': 'application/json'},
      body: myJSONData
    })
    .then(response => {console.log(response);})
    .catch(error => {console.log(error);})
    .then(response => {console.log(response);});

[junggu_choi]

Thank you for your reply!

I tried to your code writed below!

  fetch('http://10.100.28.120:8080', {
      method: 'POST',
      headers:{'Content-Type': 'application/json'},
      body: posted_data
    })
    .then(response => {"response: "+console.log(response);})
    .catch(error => {"error: "+console.log(error);})
    .then(response => {"response: "+console.log(response);});

But, I get error message "TypeError: Failed to fetch" and "undefined".

I thinkTypeError is caused by data receiving in the web rather than posting data from the fetch function.

I wonder what you think.

[philvms · Accepted solution]

Hard to say without seeing the server code.

Just start doing standard debugging to verify certain parts are working and work your way down to the point of failure.