Setting a cookie server side with `use_cookie` doesn't set anything

[steadygaze]

Hello, thanks for creating all these helpers! I've been wondering if I've been doing something horribly wrong, but the use_cookie helper doesn't seem to actually be able to set cookies in server functions. Meanwhile, it is possible to set cookies in server functions using leptos_actix. I gave the source code a cursory look, and that seems to be what it's doing, so I'm not sure what's going wrong.

I've created a minimal example demonstrating this: steadygaze/start-actix-use-cookie-repro@b45e30d

So, there is this note in the Leptos-Use site

This works equally well on the server or the client. On the server this function reads the cookie from the HTTP request header and writes it back into the HTTP response header according to options (if provided). The returned WriteSignal may not affect the cookie headers on the server! It will try and write the headers buy if this happens after the headers have already been streamed to the client then this will have no effect.

but I don't think streaming is coming into play if leptos_actix is able to set the headers still.

---

Secondarily, cookies updated on the server won't update in SSR, but the docs already note this. Is there a way to say "ok, recheck the cookies now because I think they might've changed"? (For context, this is the general thing I'm trying to do: leptos-rs/leptos#3609.)

[maccesch]

This function is not meant to be used inside server functions. You can use it in a component and it will work when the component is rendered on the server as well as the browser.

I guess a helper utility for using in server functions would be helpful, but we don't have that yet.

[steadygaze]

Thanks for your reply; I will use the regular leptos_actix API in server functions for now. It is a bit of a gotcha for newbies because it builds just fine. If I have time I might help update the docs? Not sure if there is a way to detect if we're running in a server function and log a warning, but that might be nice too.

Making use_cookie or another helper work in server functions wouldn't be strictly necessary, but it would be a lot more concise. Making examples of some code I'm working on, this is what a usage of use_cookie might look like,

    let (_, set_login_email) = use_cookie_with_options::<String, FromToStringCodec>(
        "login_email",
        UseCookieOptions::default()
            .path("/"), // Must be / for SSR; server functions will be under /api.
            .same_site(SameSite::Lax)
    );
    set_login_email(Some(email));

while this is what the leptos_actix API looks like,

    let response_options = use_context::<leptos_actix::ResponseOptions>()
        .ok_or_else(|| ServerFnError::new("No response options object"))?;

    let email_cookie = Cookie::build("login_email", email)
        .path("/") // Must be / for SSR; server functions will be under /api.
        .same_site(cookie::SameSite::Lax)
        .finish();

    response_options.append_header(
        SET_COOKIE,
        HeaderValue::from_str(&email_cookie.to_string()).map_err(|err| {
            ServerFnError::new(format!(
                "Email should always encode successfully, but got: {err}"
            ))
        })?,
    );

and there's not even any consideration for codec encode/decode functionality, which is really nice.