Cannot find a good example how to handle HTTP POST in Rust(update)

Developers
1

I need to implement http_request_update
but there’s NO documentation available

What’s going on with HTTPS gateways and incoming requests | Internet Computer ?..

3

You’re right, this should be documented better. The right place to read about http_request_update is here.

This section in the page you linked is partially correct:

To handle incoming HTTP requests, canisters must define methods for http_requests and http_requests_update for GET and POST requests respectively.

This is just wrong. In both cases the request first goes to http_request and only if you return upgrade: true will it be upgraded and re-called as http_request_update. The HTTP method does not matter.

All HTTP requests are handled by the ICP HTTP Gateway, therefore you cannot make direct POST calls to a canister’s http_request_update method with HTTP clients such as curl. Instead, you can make a POST call to a canister’s HTTP endpoint, then configure the canister’s http_request method to upgrade the call to http_request_update if necessary.

This part is correct and explains how to make the gateway call _update.

The exact types you need to implement are defined here.

4

Yea, already figured this out.

It’s just it took me like 3 hours., a task that should be doable in 15 min max with good documentation…

Those rust structs aren’t even exported anywhere from ic_cdk official rust crate, so I had to hack on a knee while debugging candid errors and trying to find this in the spec and see what am I even doing wrong

Poor devs who gonna use this for ICP

GET calls were easy because there are good examples, but POST… ugh

5

Sharing here in case it saves anyone hours of debugging in 2025, here is working example repo (canister as REST API with verifications):

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