JS Fetching batch data with HTTP - javascript

My RESTful service allows batching requests.
I'm trying to combine requests into one batch with help of Fetch API:
let req1 = {
url: "/cups/count",
options: {
method: 'GET',
headers: {
'Content-Type': 'application/http'
}
}
},
req2 = {
url: "/spoons/count",
options: {
method: 'GET',
headers: {
'Content-Type': 'application/http'
}
}
},
authToken = "Bearer my_token123",
batchUrl = "http://something.com/batch",
options = {
method: 'POST',
headers: {
'Authorization': authToken,
'Content-Type': 'multipart/mixed'
},
body: {req1, req2}
};
return fetch(batchUrl, options)
.then(response => response.json())
.then(items => dispatch(batchSuccess(items)))
.catch((err) => {
console.log(err)
});
However it returns an error - bad request. I suppose I may combine HTTP requests in wrong way.
Is there simpler way of doing this?
Where in Network Chrome Dev Tools can I see nested HTTP requests?

Your code does not work because it does not follow multipart/mixed request format:
In Content-Type header, there is no boundary information.
The child requests are not divided by boundary, instead they will be sent as plain text of req1 & req2 object.
In order to send valid multipart/mixed request, there is a node.js module batchelor. According to the introduction page, its usage is pretty simple.
If you want to send multipart/mixed request from browser, you can use build tool (gulp, webpack etc.) to compile batchelor into something like "batchelor-compiled.js" and import it in HTML.
For developer tool, I didn't find anything in Chrome, but the child requests are visible in Firefox debug window's "Params" tab.

Here is an example of a batch request using the Fetch API with the Gmail Batch REST API.
This will get the content of several messages at once.
const response = await fetch("https://www.googleapis.com/batch/gmail/v1", {
headers: {
"Content-Type": "multipart/mixed; boundary=batch_boundary",
Authorization: "Bearer <access_token>",
},
method: "POST",
body: `--batch_boundary
Content-Type: application/http
Content-ID: 1
GET /gmail/v1/users/me/messages/{message-id-1}
--batch_boundary
Content-Type: application/http
Content-ID: 2
GET /gmail/v1/users/me/messages/{message-id-2}
--batch_boundary--`,
});
console.log(await response.text());

Related

Trying to use fetch instead of axios to make a POST request, but the response from the fetch request returns an error, whereas axios doesn't

I have a function which uses Axios to send a POST request which goes through successfully and I get the right response. Now I want to try using fetch to do the exact same POST request. Unfortunately, the fetch request returns a 415 Unsupported Media Type response error and I have no idea why.
Currently:
onBeforeUnload = () => {
try {
const defaultPresence = {
presence: 'AVAILABLE',
message: '',
};
const url = getServerURL() + urls.PRESENCE;
axios.post(
url,
defaultPresence,
{
headers: {
Authorization: `Bearer ${getAccessToken()}`,
},
},
);
} catch (error) {
console.log(error);
}
}
The fetch code I've used to replace the Axios POST request.
fetch(url, {
method: 'POST',
headers: {
Authorization: `Bearer ${getAccessToken()}`,
},
body: defaultPresence,
});
fetch does not recognise plain objects as the body.
If you want to send JSON then you need to encode the data and set the content-type header yourself.
fetch(url, {
method: 'POST',
headers: {
Authorization: `Bearer ${getAccessToken()}`,
"Content-Type": "application/json",
},
body: JSON.stringify(defaultPresence),
});

Response 400 for Fetch API call

I am trying to make a call using JavaScript's Fetch API to generate an OAuth Token but I keep receiving a 400 response code and I'm not sure why. I wrote the key and secret to the console to verify their values, and I made the same API call using cURL (with the response I expected). Is there a small issue in my syntax?
fetch('https://api.petfinder.com/v2/oauth2/token', {
method: 'POST',
body: 'grant_type=client_credentials&client_id=' + key + '&client_secret=' + secret
}).then(r => { response = r.json() });
If the request body is a string, the Content-Type header is set to text/plain;charset=UTF-8 by default. Since you're sending urlencoded data, you have to set the Content-Type header to application/x-www-form-urlencoded.
fetch('https://api.petfinder.com/v2/oauth2/token', {
method: 'POST',
headers: {
'Content-Type': 'application/x-www-form-urlencoded',
},
body: 'grant_type=client_credentials&client_id=' + key + '&client_secret=' + secret
})
As I mentioned in a comment, you shouldn't make the above request from a browser since it exposes the client secret.
Thanks to #Arun's recommendation of adding Content-Type, I am getting the right response now.
Also, for any other JavaScript newbies playing around with the petfinder API, this is the chain that I used to extract the token from the response:
fetch('https://api.petfinder.com/v2/oauth2/token', {
method: 'POST',
headers: {
'Content-Type': 'application/x-www-form-urlencoded',
},
body: 'grant_type=client_credentials&client_id=' + key + '&client_secret=' + secret
}).then(response => response.json().then(data => ({
data: data,
status: response.status})
).then(function(res) {
console.log(res.status, res.data.access_token);
}));

npm start gets 401 and node app.js gets 200 response

I have a React project that I run with npm start and this code gets 401 Error from the second fetch (the first one is ok). It runs fine returning 200 only with node, like in "node App.js".
So what would I need to do to run my React project getting 200 response? Why is there this difference between npm and node to this request response?
const clientID = <ClientID>
const clientSecret = <ClientSecret>
const encode = Buffer.from(`${clientID}:${clientSecret}`, 'utf8').toString('base64')
const requestOptions = {
method: 'POST',
headers: { 'Content-Type': 'application/x-www-form-urlencoded',
'Authorization': `Basic ${encode}`,
},
};
fetch("https://auth-nato.auth.us-east-1.amazoncognito.com/oauth2/token?grant_type=client_credentials", requestOptions)
.then(response => { return response.json() })
.then(data => {
const requestOptions2 = {
method: 'POST',
mode: 'no-cors',
headers: { 'Content-Type': 'application/json',
'Authorization': `Bearer ${data.access_token}`
},
body: '{"username":"Ana", "password":"test123","user_id":"ana#email.com"}'
};
fetch('https://j1r07lanr6.execute-api.sa-east-1.amazonaws.com/v1/register', requestOptions2)
.then(response => {console.log(response)});
})
Buffer - is not presented in the browser's javascript.
Instead of
const encode = Buffer.from(`${clientID}:${clientSecret}`, 'utf8').toString('base64')
use just
const encode = btoa(`${clientID}:${clientSecret}`);
Read more about base64 encoding on MDN.
I found out it was a CORS issue that needed to be set correctly on the back-end. My workaround was disabling chrome web security and removing "mode: no-cors".
I've tried adding "Access-Control-Allow-Origin":"http://localhost:3000" to headers but it doesn't work.

Upload Excel File from React to C# ASP.NET Core backend

I am trying to upload a file from a react front end to a C# backend. I am using drop zone to get the file and then I call an api helper to post the file but I am getting different errors when I try different things. I am unsure exactly what the headers should be and exactly what I should send but I get two distinct errors. If I do not set the content-type I get 415 (Unsupported Media Type) error. If I do specify content type as multipart/form-data I get a 500 internal server error. I get the same error when the content-type is application/json. The url is being past in and I am certain it is correct. I am unsure if the file should be appended as file[0][0] as I have done or as file[0] as it is an array but I believe it should be the first. Any suggestions welcome :) Here is my api post helper code:
export const uploadAdminFile = (file, path, method = 'POST', resource =
config.defaultResource) => {
const url = createUrl(resource, path);
const data = new FormData();
data.append('file', file[0][0]);
data.append('filename', file[0][0].name);
const request = accessToken =>
fetch(
url,
{
method,
mode: 'cors',
withCredentials: true,
processData: false,
headers: {
Accept: 'application/json',
'Content-Type': 'application/json', //'multipart/form-data',
Authorization: `Bearer ${accessToken}`,
},
body: data,
})
.then(res => res.json())
.then(success => console.log('API HELPER: file upload success: ', success)
.catch(err => console.log('API HELPER: error during file upload: ', err)));
return sendRequest(request, resource);
};
Thanks for the help and suggestions, it turned out to be a backend issue but even still I learned a lot in the process. I will post my working code here in case anyone comes across this and finds it useful.
export const uploadAdminFile = (file, path, resource=config.defaultResource) => {
const url = createUrl(resource, path);
const formData = new FormData();
formData.append('file', file[0][0]);
formData.append('filename', file[0][0].name);
const request = accessToken =>
fetch(url,
{
method: 'POST',
headers: {
Accept: 'application/json',
Authorization: `Bearer ${accessToken}`,
},
body: formData,
});
return sendRequest(request, resource);
};
As mentioned, the file name does not need to be sent separately and count be omitted. I am indexing the file this way because I get it from dropzone as an array and I only want a single file (the first one in the array). I hope this helps someone else out and here is a link to the mdn fetch docs (good information) and a good article on using fetch and formData.

Unable to fetch POST without no-cors in header

On making request like that:
return fetch(
'http://localhost:8000/login',
{ method: 'POST',
headers: new Headers(
{"Content-Type": "application/json",
"Accept":"application/json"}
),
body: JSON.stringify(
{'name': 'Tom', 'password': 'Soyer'}
)
}
).then( response => { console.log(response);})
.catch(err => console.log(err))
request running with method OPTIONS instead POST.
Only on adding mode: 'no-cors' request become POST:
return fetch(
'http://localhost:8000/login',
{ method: 'POST',
mode: 'no-cors',
headers: new Headers(
{"Content-Type": "application/json",
"Accept":"application/json"}
),
body: JSON.stringify(
{'name': 'Tom', 'password': 'Soyer'}
)
}
).then( response => { console.log(response);})
.catch(err => console.log(err))
but response not ok than (even if network response status is 200): {type: "opaque", url: "", status: 0, ok: false, statusText: ""…}
I suppose it because
The only allowed values for the Content-Type header are:
application/x-www-form-urlencoded multipart/form-data text/plain
described here https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS
Is any way bring to live POST json data with fetch?
The custom Content-Type header you're sending causes your request to be preflighted, which means an OPTIONS request, containing some metadata about the POST request that is about to be dispatched, will be sent before the actual POST request.
Your server needs to be prepared to deal with this OPTIONS request. You haven't specified what the server is written in, but with express for example, you can register a middleware that intercepts all 'OPTIONS' requests, sets the Access-Control-Allow-Origin: * and Access-Control-Allow-Headers: Content-Type headers, and responds with 200.
If it is possible for you to make the request using a 'Content-Type': 'text/plain' header, that would solve your problem. Alternatively you could use something that bypasses XHR entirely, like JSONP.
When using non-cors, all headers must be valid simple-headers. The only valid values for the content-type header that qualifies as a simple-header is:
headers: [
['Content-Type', 'application/x-www-form-urlencoded'],
['Content-Type', 'multipart/form-data'],
['Content-Type', 'text/plain'],
]
Exceptions with contingencies:
headers: [
['Content-Type', 'application/csp-report'],
['Content-Type', 'application/expect-ct-report+json'],
['Content-Type', 'application/xss-auditor-report'],
['Content-Type', 'application/ocsp-request'],
]
simple-header
cors-protocol-exceptions
If you are trying to call an api and getting stuck with this in your react app you can add a proxy to the server and the cors error will get removed
just add this line at the package.json
"proxy":"url-to-your-server",

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