This is the first form that uses HTMx, and can not return a 400 error
code because otherwise HTMx does not render the content.
Since now there are pages that do not render the whole html, with header
and body, i need a different layout for these, and moved the common code
to handle forms and such a new template file that both layouts can use.
I also need the request in template.MustRender to check which layout i
should use.
Closes#7.
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.
jordi fita mas