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I have a problem with handling POST requests in Google Apps Script. I've created simple project with following functions:

function doGet(e){
  return ContentService.createTextOutput("test").setMimeType(ContentService.MimeType.TEXT);
}

function doPost(e){
  return ContentService.createTextOutput("test").setMimeType(ContentService.MimeType.TEXT);
}

When I try to send a GET request from postman I get correct response - as expected. However when I try to send POST request I get 405 Method not allowed and HTML error page in response. In deployment settings I set that it should execute as me and should be accessible to everyone.

What am I missing? How to make POST requests work with Google Apps Script?

EDIT: So as Heiko Theißen wrote below there is 302 redirect at first. fiddler screenshot

As I can see Postman follows that redirect and sends POST once again to new URL but this request fails and I still don't know why unfortunately. I can see in security section that there is header Allow: HEAD, GET. fiddler screenshot

I cannot see any preflight request from Postman (as TheMaster suggested).

About reproducibility: I've pasted complete content of google apps script, and I mentioned that I am making request from postman. Here is link to current deployment of that script: https://script.google.com/macros/s/AKfycbyHdVpclM7pH1BB3IzwNjtcH07DF75H8ldqeLQCwQnX71lMs371g-UO-i8JaI5_zRqrDw/exec

Also here is screenshot from Postman - I'm just sending empty POST request without any custom headers. Tried also sending plain text or json as payload but results were the same each time. postman headers screenshot postman body screenshot

So back to my original question: How can I receive POST request successfully in google apps script deployed as Web App?

TheMaster
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Mateusz Marchel
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  • About `How to make POST requests work with Google Apps Script?`, can I see your current script? – Tanaike Dec 22 '22 at 01:07
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    Provide [mcve] in the future. Probably, Your requests are preflighted because it's not a simple request. You're probably posting json. Read about CORS. – TheMaster Dec 22 '22 at 04:52
  • @TheMaster added more info in original question. As far as i know and can see in fiddler: Postman doesn't send preflight requests. – Mateusz Marchel Dec 22 '22 at 11:14
  • @Tanaike I've posted example in question above. It's minimal - just two methods: `doGet()`, and `doPost()`. Making requests via postman works fine when I'm sending `GET` requests but fails for `POST`. – Mateusz Marchel Dec 22 '22 at 11:17

2 Answers2

3

I make it workable from postman by disabling the annotated option from settings.

enter image description here

Naeem Ahmed
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2

If the preflight explanation given by TheMaster does not solve your problem, the following might help:

Requests to Google Apps Script always happen in two stages: The first request draws a redirection response to a generated URL, and the second request to that URL draws the response that you programmed (the text output "test").

When the first request is a POST request, the redirection response has status "302 Found", and the specification is ambiguous about what method the second request should have:

Note: For historical reasons, a user agent MAY change the request method from POST to GET for the subsequent request. If this behavior is undesired, the 307 (Temporary Redirect) status code can be used instead.

Google Chrome makes the second request as a GET request (without repeating the POST payload, which the server already knows under the generated URL) and this works.

However, if your browser or Postman client does not change the method and makes the second request again as a POST (and your screenshot shows this is true), the server does not accept this and responds with "405 Method Not Allowed".

In other words: Google Apps Script expects the second request to be a GET request, but not all clients behave like that, because the specification is ambiguous at this point. Workarounds:

  • You can influence the behavior of Postman so that it does not preserve the POST method between the first and second request. See here.
  • Google Apps Script could avoid the ambiguity by responding to the first request with "303 See Other", but it does not. Perhaps create an issue for that?
Heiko Theißen
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