# Proper example of handling HTTP GET request in Rust

**URL:** <https://forum.dfinity.org/t/proper-example-of-handling-http-get-request-in-rust/34725>\
**Category:** Rust\
**Created:** [September 3, 2024, 6:23pm UTC](https://forum.dfinity.org/t/proper-example-of-handling-http-get-request-in-rust/34725 "2024-09-03T18:23:07Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![ycomb](https://avatars.discourse-cdn.com/v4/letter/y/a88e4f/32.png) [@ycomb](https://forum.dfinity.org/u/ycomb)\
**Post date:** [September 3, 2024, 6:23pm UTC](https://forum.dfinity.org/t/proper-example-of-handling-http-get-request-in-rust/34725/1 "2024-09-03T18:23:07Z")

</div>

I’m a newcomer and I’m lost in examples, can’t find proper.

I’d like a canister to handle HTTP requests. I see it should implement `http_request`. I defined did as follows:

```did
type header = record {
  name : text;
  value : text;
};
type request = record {
  method : text;
  url : text;
  headers : vec header;
  body : blob;
};
type response = record {
  status_code : nat16;
  headers : vec header;
  body : blob;
};
service : {
  http_request : (request) -> (response);
}

```

Then Rust implementation:

```Rust
#[derive(CandidType, Deserialize)]
pub struct HeaderField {
    pub name: String,
    pub value: String,
}

#[derive(CandidType, Deserialize)]
pub struct HttpRequest {
    pub method: String,
    pub url: String,
    pub headers: Vec<HeaderField>,
    pub body: Vec<u8>,
}

#[derive(CandidType)]
pub struct HttpResponse {
    pub status_code: u16,
    pub headers: Vec<HeaderField>,
    pub body: Vec<u8>,
}

```

I deploy it to `ic`. It returns the canister ID: `3sanc-...-cai`. Then I try to curl it with: `curl -X GET "https://3sanc-...-cai.raw.icp0.io/query"`. It fails with the error:

```auto
Replica Error: reject code CanisterError, message IC0503: Error from Canister 3sanc-...-cai: Canister called `ic0.trap` with message: failed to decode call arguments: Custom(Fail to decode argument 0 from table0 to record {
  url : text;
  method : text;
  body : blob;
  headers : vec record { value : text; name : text };
}

Caused by:
    Subtyping error: text).
Consider gracefully handling failures from this canister or altering the canister to handle exceptions. See documentation: http://internetcomputer.org/docs/current/references/execution-errors#trapped-explicitly, error code Some("IC0503")

```

And I have no idea where it errors with `text` subtyping. Any suggestions what’s the problem and how to fix it?

---

<div class="post-metadata">

**Author:** ![Vivienne](https://sea1.discourse-cdn.com/flex023/user_avatar/forum.dfinity.org/vivienne/32/29170_2.png) [@Vivienne](https://forum.dfinity.org/u/Vivienne)\
**Post date:** [September 4, 2024, 10:50am UTC](https://forum.dfinity.org/t/proper-example-of-handling-http-get-request-in-rust/34725/2 "2024-09-04T10:50:10Z")

</div>

From the [spec](https://internetcomputer.org/docs/current/references/http-gateway-protocol-spec#canister-http-interface):

```candid
type HeaderField = record { text; text; };

```

but you define

```candid
headers : vec record { value : text; name : text };

```

If you use a tuple instead of a struct it should work:

```rust
pub type HeaderField = (String, String);

```