I do not want to use floats in the Go lang application, because it is
not supposed to do anything with these values other than to print and
retrieve them from the user; all computations will be performed by
PostgreSQL in cents.
That means i have to “convert” from the price format that users expect
to see (e.g., 1.234,56) to cents (e.g., 123456) and back when passing
data between Go and PostgreSQL, and that conversion depends on the
currency’s decimal places.
At first i did everything in Go, but saw that i would need to do it in
a loop when retrieving the list of products, and immediately knew it was
a mistake—i needed a PL/pgSQL function for that.
I still need to convert from string to float, however, when printing the
value to the user. Because the string representation is in C, but i
need to format it according to the locale with golang/x/text. That
package has the information of how to correctly format numbers, but it
is in an internal package that i can not use, and numbers.Digit only
accepts numeric types, not a string.
Our company is a kind-of contact, although it does not appear in the
contact section, thus i could embed the contact form inside the tax
details form to reuse all the common fields.
I implemented the Valuer and Scanner interfaces to InputField and
SelectField for better passing values between the database and Go. I
had a conflict with the Value name and renamed the struct member to Val.
I also had to change the attributes array to be of type
template.HTMLAttr or html/template would replace `form="newtax"`
attribute to `zgotmplz="newtax"` because it deems it “unsafe”. I do
not like having to use template.HTMLAttr when assigning values, but
i do not know what else i can do now.
I was worried that i was repeating the AddInputErrors function for each
form, because they were basically the same. I could create a Form type
and make all forms embed it, but i realized that with a separate
validator i would have cleaner validation functions and would not need
the Valid field in the form that i am using only for that method.
Similar to the profile form, the login form now parses and validates
itself, with the InputField structs that the templates expect.
I realized that i was doing more work than necessary when parsing fields
fro the profile form because i was repeating the operation and the field
name, so now it is a function of InputField.
This time i needed extra attributes for the login form. I am not sure
that the Go source code needs to know about HTML attributes, but it was
the easiest way to pass them to the template.
This is just to set the correct `lang` attribute on the HTML, so that
text readers can do its job and the `(optional)` suffix of labels gets
the correct ”translation”.
Let’s start first with a non-fancy validation method with just if
conditionals instead of bringing yet another complicated library. I
hope i do not regret it.
I wanted to move all the input field to a template because all that
gobbledygook with the .input div and repeating the label in the
placeholder was starting to annoy me. Now with error messages was even
more concerning.
I did not know whether the label should be a part of the input fields
or something that the template should do. At the end i decided that
it makes more sense to be part of the input field because in the error
messages i use that same label, thus the template does not have a say
in that, and, besides, it was just easier to write the template.
The same with the error messages: i’ve seen frameworks that have a map
with the field’s id/name to the error slice, but then it would be
a bit harder to write the template.
I added AddError functions instead of just using append inside the
validator function, and have a local variable for whether it all went
OK, because i was worried that i would leave out the `ok = false`
in some conditions.
I had started writing “constructors” functions for InputField and
SelectField, but then had to add other methods to change the required
field and who knows what else, and in the end it was easier to just
construct the field inline.
I have been thinking about that, and it does not make that much sense to
have the titles in the Go source anymore: most of them are static text
that i have to remember to set in the controller each time, and when
the time come i have to face a dynamic title i am sure i will manage
with only the template capabilities—worst comes worst, i can always
define a function.
On the other hand, there is no way i can define a template without its
title and i know that everytime that template is used, no matter what
controller rendered it, it will always have that title.
This is not necessary per se, but it makes my life easier because that
way i know which company the user was when she went to its profile and
can “return” back in the menu and future nav items.
At first we thought that a regular text field would do, because we were
afraid that a dropdown would be worse from the point of view of user
experience, but then we realized that we need the country code for VAT
and phone validation, and we can not expect users to input that, of
course.
I had to add the first “i18n table” to the database with the name of all
countries in both Catalan and Spanish and Catalan; English is the
default. For now i think i do not need a view that would select the
name based on the locale of the current request, because currently i do
not plan on adding any other such table —the currency uses the code and
the symbol, thus no need for localization.
However, now i need the language tag from the locale in order to get the
correct translation, and gotext does not give me any way to access the
inner language. Thus the need for our Locale type.
I do not have more time to update the update to the company today, but i
believe this is already a good amount of work for a commit.
The company is going to be used for row level security, as users will
only have access to the data from companies they are granted access, by
virtue of being in the company_user relation.
I did not know how add a row level security policy to the company_user
because i needed the to select on the same relation and this is not
allowed, because it would create an infinite loop.
Had to add the vat, pg_libphonenumber, and uri extensions in order to
validate VAT identification numbers, phone numbers, and URIs,
repectively. These libraries are not in Debian, but i created packages
for them all in https://dev.tandem.ws/tandem.
This function does not ask for the confirmation because this is an
user-facing issue, not for the database.
Still missing: validation and proper error messages.
This is for security, just in case two users have the same cookie,
althought it is unlikely, but nevertheless less guessable.
I also need to refresh the cookie when the user changes their email
address, because it is liked toghether. It does mean that it will
logout from everywhere else, but i can not do anything about that.
I want this so that the Go application does not need to know the exact
details of the settings that the database sets when applying the cookie;
it just needs to select from the user_profile that already knows this.
Also, that way i can get the user’s language from its profile with a
single select, without having to check whether we are guest or
authenticated.
With that, i can skip the content negotiation if the user already told
us what language they want.
Had to call xgettext on Go source files because now the title comes from
there, as i assume i will have titles like "Invoice #INVxxxx" that have
to come from the database that the template does not know.
Since users do not have access to the auth scheme, i had to add a view
that selects only the data that they can see of themselves (i.e., no
password or cookie).
I wanted to use the `request.user.id` setting that i set in
check_cookie, but this would be bad because anyone can change that
parameter and, since the view is created by the owner, could see and
*change* the values of everyone just by knowing their id. Thus, now i
use the cookie instead, because it is way harder to figure out, and if
you already have it you can just set to your browser and the user is
fucked anyway; the database can not help here.
I **am** going to use the user id in row level security policies, but
not the value coming for the setting but instaed the one in the
`user_profile`, since it already is “derived” from the cookie, that’s
why i added that column to the view.
The profile includes the language, that i do not use it yet to switch
the locale, so i had to add a relation of the available languages, for
constraint purposes. There is no NULL language, and instead i added the
“Undefined” language, with ‘und’ tag’, to represent “do not know/use
content negotiation”.
The languages in that relation are the same i used to have inside
locale.go, because there is no point on having options for languages i
do not have the translation for, so i now configure the list of
available languages user in content negotiation from that relation.
Finally, i have added all font from RemixIcon because that’s what we
used in the design and i am going to use quite a lot of them.
There is duplication in the views; i will address that in a different
commit.
I did not like the idea that it was the Go server who should set values
such as request.user or set the role, because this is mostly something
that only the database wants for itself, such as when calling logout. I
am also planning to use these setings for row security with the user’s
id, that the Go application has no need for, but with the current
approach i would need to return it from check_cookie so that it can
return it back to the database when acquiring the connection.
I would have used the same function to set the settings and the role,
but security definer functions—obviously in retrospect—can not set the
role, because then could switch to any role of the user that defined the
function, not the roles they are member of. Thus, a new function.
I did not want to do that every time i needed the database connection
within the same request, because it would perform the same operations
each time—it is the same cookie, afterall—, so new connections are
request scoped and passed along in the context.
I had to choose between [1], [2], and [3].
As far as i could find, [1] is not easy to work with templates[4] and at
the moment is not maintained[5].
Both [2] and [3] use the same approach to be used from within templates:
you have to define a FuncMap with template functions that call the
message catalog. Also, both libraries seems to be reasonably
maintained, and have packages in Debian’s repository.
However, [2] repeats the same mistakes that POSIX did with its
catalogs—using identifiers that are not the strings in the source
language—, however this time the catalogs are written in JSON or YAML!
This, somehow, makes things worse….
[3], the one i settled with, is fine and decently maintained. There are
some surprising things, such as to be able to use directly the PO file,
and that it has higher priority over the corresponding MO, or that the
order of parameters is reversed in respect to gettext. However, it uses
a saner format, and is a lot easier to work with than [3].
The problem, of course, is that xgettext does not know how to find
translatable strings inside the template. [3] includes a CLI tool
similar to xgettext, but is not a drop-in replacement[6] and does not
process templates.
The proper way to handle this would be to add a parser to xgettext, but
for now i found out that if i surround the call to the translation
functions from within the template with parentheses, i can trick
xgettext into believing it is parsing Scheme code, and extracts the
strings successfully—at least, for what i have tried. Had to add the
keyword for pgettext, because Schemed does not have it, but at least i
can do that with command line parameters.
For now i left only Spanish and Catalan as the two available languages,
even though the source text is written in English, because that way i
can make sure i do not leave strings untranslated.
[1]: https://golang.org/x/text
[2]: https://github.com/nicksnyder/go-i18n
[3]: https://github.com/leonelquinteros/gotext
[4]: https://github.com/golang/go/issues/39954
[5]: https://github.com/golang/go/issues/12750
[6]: https://github.com/leonelquinteros/gotext/issues/38
At first i thought that i would need to implement sessions, the ones
that keep small files onto the disk, to know which user is talking to
the server, but then i realized that, for now at least, i only need a
very large number, plus the email address, to be used as a lookup, and
that can be stored in the user table, in a separate schema.
Had to change login to avoid raising exceptions when login failed
because i now keep a record of login attemps, and functions are always
run in a single transaction, thus the exception would prevent me to
insert into login_attempt. Even if i use a separate procedure, i could
not keep the records.
I did not want to add a parameter to the logout function because i was
afraid that it could be called from separate users. I do not know
whether it is possible with the current approach, since the settings
variable is also set by the same applications; time will tell.
The whole application will need the same search_path, so it is wasteful
to do that in each handler.
It is possible to pass the search path as a parameter to the database’s
connection string, but then everyone would need to remember to do that,
and update the configuration in case i add another schema.
Similarly, i need to change the user’s role to match her
permissions—which are not in yet—, but this time i need it each time a
handler requests a connection from the pool, because each time the
connection is returned to the pool i reset the role back to the initial,
that hopefully will be authenticator.
I do not yet know how i will need to organize them, if indeed i need to
organize them to a finer granularity than single files, so there is no
point on doing Java-like packages.
I’ve tried to make RPM packages of numerus and pgx/v4 for AlmaLinux, so
install in a virtual server, but i was unable to break a build cycle
between golang/x/text, required by pgx, and golang/x/tools both a
dependency and a dependee of golang/x/text: once tools finished
building, it would trigger a new build for text, that in turn would
trigger a build for all its dependences, including tools.
At the end i had to create a Debian repository, because they already
have all the packages, even though i had to back port pgx/v4 from
Testing to bullseye. I did not want to try my luck with writting
packages for pgx/v5, so v4 it is.
This is a very rough test to actually check the login function outside
pgTAP; it is very ugly, in both design and code, and (i hope) does not
reflect future quality.
I was about to use Echo[0] as a “web framework”, but something feels
wrong when using a framework with Go—i do not know what. I actually
tried it and was even more put off by the JSON-formatted logger that can
not be disabled; i was already losing control of the application!
I created the folder following the apparently de facto guidelines for Go
projects, and i see no problem with mixing Go’s folders with Sqitch’s:
both are part of the same application and there are not conflicts.
[0]: https://echo.labstack.com/
[1]: https://github.com/golang-standards/project-layout
jordi fita mas