Conceptually, to logout we have to “delete the session”, thus the best
HTTP verb would be `DELETE`. However, there is no way to send a
`DELETE` request with a regular HTML form, and it seems that never will
be[0].
I could use a POST, optionally with a “method override” technique, but
i was planing to use HTMx anyway, so this was as good an opportunity to
include it as any.
In this application i am not concerned with people not having JavaScript
enabled, because it is for a customer that has a known environment, and
we do not have much time anyway. Therefore, i opted to forgo
progressive enhancement in cases like this: if `DELETE` is needed, use
`hx-delete`.
Unfortunately, i can not use a <form> with a hidden <input> for the
CSRF token, because `DELETE` requests do not have body and the value
should be added as query parameters, like a form with GET method, but
HTMx does the incorrect thing here: sends the values in the request’s
body. That’s why i have to use a custom header and the `hx-header`
directive to include the CSRF token.
Then, by default HTMx targets the triggered element for swap with the
response from the server, but after a logout i want to redirect the
user to the login form again. I could set the hx-target to button to
replace the whole body, or tell the client to redirect to the new
location. I actually do not know which one is “better”. Maybe the
hx-target is best because then everything is handled by the client, but
in the case of logout, since it is possible that i might want to load
scripts only for logged-in users in the future, i opted for the full
page reload.
However, HTMx does not want to reload a page that return HTTP 401,
hence i had to include the GET method to /login in order to return the
login form with a response of HTTP 200, which also helps when
reloading in the browser after a failed login attempt. I am not worried
with the HTTP 401 when attempting to load a page as guest, because
this request most probably comes from the browser, not HTMx, and it will
show the login form as intended—even though it is not compliant, since
it does not return the WWW-Authenticate header, but this is the best i
can do given that no cookie-based authentication method has been
accepted[1].
[0]: https://www.w3.org/Bugs/Public/show_bug.cgi?id=10671#c16
[1]: https://datatracker.ietf.org/doc/id/draft-broyer-http-cookie-auth-00.html
It is a lot of code having to check the login variables inside the POST
handler, and i could not mark each input field individually as invalid
because the generic errors array i was using did no identify which field
had the error.
Thus, i use more or less the same technique as with Numerus: a struct
with the value and the error message. This time the input field does
not have the label and extra attributes because i believe this belongs
to the template: if i want do reuse the same form template, i should
create a common template rather than defining everything in Go.
The name is a bit different, however, because it has meaning both to the
front and back ends, as it needs to be exactly the same. Writing it
twice is error-prone, as with a rename i could easily forget to change
one or the other, and here i see value in having that in Go, because
it is also used in code.
It does nothing more than to server a single page that does nothing
interesting.
This time i do not use a router. Instead, i am trying out a technique
i have seen in an article[0] that i have tried in other, smaller,
projects and seems to work surprisingly well: it just “cuts off” the
URI path by path, passing the request from handler to handler until
it finds its way to a handler that actually serves the request.
That helps to loosen the coupling between the application and lower
handlers, and makes dependencies explicit, because i need to pass the
locale, company, etc. down instead of storing them in contexts. Let’s
see if i do not regret it on a later date.
I also made a lot more packages that in Numerus. In Numerus i actually
only have the single pkg package, and it works, kind of, but i notice
how i name my methods to avoid clashing instead of using packages for
that. That is, instead of pkg.NewApp i now have app.New.
Initially i thought that Locale should be inside app, but then there was
a circular dependency between app and template. That is why i created a
separate package, but now i am wondering if template should be inside
app too, but then i would have app.MustRenderTemplate instead of
template.MustRender.
The CSS is the most bare-bones file i could write because i am focusing
in markup right now; Oriol will fill in the file once the application is
working.
[0]: https://blog.merovius.de/posts/2017-06-18-how-not-to-use-an-http-router/
jordi fita mas