When i wrote the functions to import contact, i already created a couple
of “temporary” functions to validate whether the input given from the
Excel files was correct according to the various domains used in the
relations, so i can know whether i can import that data.
I realized that i could do exactly the same when validating forms: check
that the value conforms to the domain, in the exact same way, so i can
make sure that the value will be accepted without duplicating the logic,
at the expense of a call to the database.
In an ideal world, i would use pg_input_is_valid, but this function is
only available in PostgreSQL 16 and Debian 12 uses PostgreSQL 15.
These functions are in the public schema because initially i wanted to
use them to also validate email, which is needed in the login form, but
then i recanted and kept the same email validation in Go, because
something felt off about using the database for that particular form,
but i do not know why.
This allows to import an Excel file exported from Holded, because it is
our own user case. When we have more customers, we will give out an
Excel template file to fill out.
Why XLSX files instead of CSV, for instance? First, because this is the
output from Holded, but even then we would have more trouble with CSV
than with XLSX because of Microsoft: they royally fucked up
interoperability when decided that CSV files, the files that only other
applications or programmers see, should be “localized”, and use a comma
or a **semicolon** to separate a **comma** separated file depending on
the locale’s decimal separator.
This is ridiculous because it means that CSV files created with an Excel
in USA uses comma while the same Excel but with a French locale expects
the fields to be separated by semicolon. And for no good reason,
either.
Since they fucked up so bad, decided to add a non-standard “meta” field
to specify the separator, writing a `sep=,` in the first line, but this
only works for reading, because saving the same file changes the
separator back to the locale-dependent character and removes the “meta”
field.
And since everyone expects to open spreadsheet with Excel, i can not
use CSV if i do not want a bunch of support tickets telling me that the
template is all in a single line.
I use an extremely old version of a xlsx reading library for golang[0]
because it is already available in Debian repositories, and the only
thing i want from it is to convert the convoluted XML file into a
string array.
Go is only responsible to read the file and dump its contents into a
temporary table, so that it can execute the PL/pgSQL function that will
actually move that data to the correct relations, much like add_contact
does but in batch.
In PostgreSQL version 16 they added a pg_input_is_valid function that
i would use to test whether input values really conform to domains,
but i will have to wait for Debian to pick up the new version.
Meanwhile, i use a couple of temporary functions, in lieu of nested
functions support in PostgreSQL.
Part of #45
[0]: https://github.com/tealeg/xlsx
These two fields are just for information purposes, as Numerus does not
have any way to wire transfer using these, but people might want to keep
these in the contact’s info as a convenience.
Since not every contact should have an IBAN, e.g., customers, and inside
SEPA (European Union and some more countries) the BIC is not required,
they are in two different relations in order to be optional without
using NULL.
For the IBAN i found an already made PostgreSQL module, but for BIC i
had to write a regular expression based on the information i gathered
from Wikipedia, because the ISO standard is not free.
These two parameters for the add_contact and edit_contact functions are
TEXT because i realized that these functions are intended to be used
from the web application, that only deals with texts, so the
ValueOrNil() function was unnecessarily complex and PostreSQL’s
functions were better suited to “convert” from TEXT to IBAN or BIC.
The same is true for EMAIL and URI domains, so i changed their parameter
types to TEXT too.
Closes#54.
We need to have contacts with just a name: we need to assign
freelancer’s quote as expense linked the government, but of course we
do not have a phone or email for that “contact”, much less a VATIN or
other tax details.
It is also interesting for other expenses-only contacts to not have to
input all tax details, as we may not need to invoice then, thus are
useless for us, but sometimes it might be interesting to have them,
“just in case”.
Of course, i did not want to make nullable any of the tax details
required to generate an invoice, otherwise we could allow illegal
invoices. Therefore, that data had to go in a different relation,
and invoice’s foreign key update to point to that relation, not just
customer, or we would again be able to create invalid invoices.
We replaced the contact’s trade name with just name, because we do not
need _three_ names for a contact, but we _do_ need two: the one we use
to refer to them and the business name for tax purposes.
The new contact_phone, contact_web, and contact_email relations could be
simply a nullable field, but i did not see the point, since there are
not that many instances where i need any of this data.
Now company.taxDetailsForm is no longer “the same as contactForm with
some extra fields”, because i have to add a check whether the user needs
to invoice the contact, to check that the required values are there.
I have an additional problem with the contact form when not using
JavaScript: i must set the required field to all tax details fields to
avoid the “(optional)” suffix, and because they _are_ required when
that checkbox is enabled, but i can not set them optional when the check
is unchecked. My solution for now is to ignore the form validation,
and later i will add some JavaScript that adds the validation again,
so it will work in all cases.
They are mostly the same as invoices, but the contact and payment method
are optional, thus, like other optionals fields, i created relations to
link these that have payment method or contact, to avoid NULL columns in
quote.
Still missing functions to add and edit quotations, and views to compute
their tax and total amount.
This is for new users that do not start using the application from the
beginning of the current fiscal year and, therefore, need to create
invoices starting from a specific number.
I had to change the constraint on the currval to allow zero, otherwise
it would not be possible to set 1 as the next number, because users
can also not delete the row.
It is a separate table because we allow expenses to not have such an
attachment, although we allow only an attachment per expense, and i do
not want to have a bunch of nullable columns for that.
I decided to keep the files in the database, contrary to “conventional
wisdom” of storing files in the filesystem, because these attachments
are invoices and such documets that are an integral part of the expense
relation. In other words, losing these files would render the expense
(almost) useless. Thus, the ACID guarantees of the database are the
most appropriate place for them.
We are going to allow invoices with products that are not (yet) inserted
into the products table.
We always allowed to have products in invoices with a totally different
name, description, price, and whatnot, but until now we had the product
id in these invoice lines for statistics purposes.
However, Oriol raised the concern that this requires for the products
to be inserted before we can create an invoice with them, and we do not
plan to have a “create product while invoicing” feature, thus it would
mean that people would need to cancel the new invoice, create the new
product, and then start the invoice again from scratch.
The compromise is to allow products in the invoice that do not have a
product_id, meaning that at the time the invoice was created they were
not (yet) in the products table. Oriol sees this stop-invoice-create-
product issue more important than the accurate statistics of product
sales, as it will probably be only one or two units off, anyway.
I did not want to allow NULL values to the invoice product’s product_id
field, because NULL means “dunno” instead of “no product”, so i had to
split that field to a separate table that relates an invoice product
with a registered product.
It all started when i wanted to try to filter invoices by multiple tags
using an “AND”, instead of “OR” as it was doing until now. But
something felt off and seemed to me that i was doing thing much more
complex than needed, all to be able to list the tags as a suggestion
in the input field—which i am not doing yet.
I found this article series[0] exploring different approaches for
tagging, which includes the one i was using, and comparing their
performance. I have not actually tested it, but it seems that i have
chosen the worst option, in both query time and storage.
I attempted to try using an array attribute to each table, which is more
or less the same they did in the articles but without using a separate
relation for tags, and i found out that all the queries were way easier
to write, and needed two joins less, so it was a no-brainer.
[0]: http://www.databasesoup.com/2015/01/tag-all-things.html
Initially, this field was meant to be left almost always blank, except
for when we deleted invoiced and had to “replace” its number with a new
invoice; using the automatic numbering in this cas would not “fill in”
the missing number in the sequence.
However, we decide to not allow removing invoicer not edit their
numbers, therefore, if everything goes as planned, there should not be
any gap in the sequence, and that field is rendered useless.
Oriol suggested making it a read-only field, both for new and edit
forms, but i do not think it makes sense to have a field if you can not
edit it at all, specially in the new invoice dialog, where it would
always be blank. In the edit form we already show the number in the
title and breadcrumbs, thus no need for the read-only field as
reference.
I still keep a Number member to the form struct, but is now a string
(kind of “a read-only field”, in a way) and just to be written in the
title or breadcrumbs. I did not like the idea of adding a new SQL
query just for that value.
With Oriol we agreed that products should have tags, too, and that the
“tag pool”, as it were, should be shared with the one for invoices and
contacts.
Had to add the `company_id` attribute in the `using` clause for `tag` in
`MustFillFromDatabase`, even though it’s not strictly necessary, because
then PostgreSQL does not know which `company_id` attribute use for the
join with `company`—the one from `product` or the one from `tag`.
With Oriol we agreed that contacts should have tags, too, and that the
“tag pool”, as it were, should be shared with the one for invoices (and
all future tags we might add).
I added the contact_tag relation and tag_contact function, just like
with invoices, and then realized that the SQL queries that Go had to
execute were becoming “complex” enough: i had to get not only the slug,
but the contact id to call tag_contact, and all inside a transaction.
Therefore, i opted to create the add_contact and edit_contact functions,
that mirror those for invoice and products, so now each “major” section
has these functions. They also simplified a bit the handling of the
VATIN and phone numbers, because it is now encapsuled inside the
PL/pgSQL function and Go does not know how to assemble the parts.
We plan to tag also contacts and products using the same tag relation,
but different invoice_tag, contact_tag, and product_tag relations for
each one. However, the logic is the same for all three, hence it makes
more sense to put it into a PL/pgSQL with dynamic SQL. Moreover, the
SQL for tagging in add_invoice and edit_invoice where almost exactly
the same, the only difference was deleting the existing tags when
editing.
I do not execute the tag_relation function in its test suite because
by itself it does nothing without supporting invoice_tag, contact_tag,
or any such relation, so it is being tested in the suite for
tag_invoice.
I had to use a deferrable foreign key because the payment methods have
a reference to the company, and the company now a circular reference to
payment method.
This was actually the (first) reason we added the tax classes: to show
them in columns on the invoice—without the class we would need a column
for each tax rate, even though they are the same tax.
The invoice design has the product total with taxes at the last column,
above the tax base, that i am not so sure about, but it seems that it
has not brought any problem whatsoever so far, so it remains as is.
Had to reduce the invoice’s font size to give more space to the table
or the columns would be right next to each other. Oriol also told me
to add more vertical spacing to the table’s footer.
We want to show the percentage of the tax as columns in the invoice,
but until now it was not possible to have a single VAT column when
products have different VAT (e.g., 4 % and 10 %), because, as far
as the application is concerned, these where ”different taxes”. We
also think it would be hard later on to compute the tax due to the
government.
So, tax classes is just a taxonomy to be able to have different names
and rates for the same type of tax, mostly VAT and retention in our
case.
The design calls for rendering all amounts with their currency symbol,
but golang.org/x/text’s currency package always render the symbol in
front, which is wrong in Catalan and Spanish, and a lot of other
languages.
Consulting the Internet, the most popular package for that is
accounting[0], which is almost as useless because they confuse locale
with the currency’s country of origin’s “usual locale” (e.g., en-US for
USD), which is also wrong: in Catalan i need to write USD prices as
"1.234,56 $" regardless of what Americans do.
With accounting i have the recourse of initializing the struct that
holds all the “locale” information, which is also wrong because i have
to define the decimal and thousands separators, something that depends
only on the locale, next to the currency’s precision, that is
locale-independent. But, since all CLDR data from golang.org/x/text
is inside an internal package, i can not access it and would need to
define all that information myself, which defeats the purpose of using
an external package.
Since for now i only need the format pattern for currency, i just saved
it into the database of available languages, that i do not expect to
grow too much.
[0]: https://github.com/leekchan/accounting
They are not functions because i need to join them with the main
invoice relation, and although possible is a bit more awkward with
functions.
The taxes have their own relation because i will need them grouped by
their name in the PDF, so it will probably be a select for that
relation.
I can not use a PostgreSQL sequence because invoices need to be gapless,
and sequences are designed to not rollback, for performance reasons. In
this case, the performance is secondary because the law does not care.
I am going to add similar functions for invoices, as i will need to
add the taxes for their products and their own taxes, thus the Go code
will begin to be “too much work” and i feel better if that is in
PL/pgSQL.
If i have these functions for invoices, there is no point on having to
do almost the same work, albeit less, for products.
I store again the product’s name, description, and prices, because they
are bound to change, but the invoice should remain the same always.
That makes me wonder if i should do the same for seller’s and buyer’s
data, but that should be a different commit.
I’ve added the discount_rate domain because then i can test it
independently of the invoice_product relation, moreover i am sure i will
need it for simplified invoices too.
It seems that we do not agree en whether the IRPF tax should be
something of the product or the contact, so we decided to make the
product have multiple taxes, just in case, and if only one is needed,
then users can just select one; no need to limit to one.
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.
jordi fita mas