This way i can use the function in the from clause of the query that
i already had to do to get the totals formatted with to_price. In this
case, i believe it is better to leave out Go’s function because it would
force me to perform two queries.
Instead of binding a nullable string pointer with the payment’s slug,
i wanted to use pgtype’s zeronull.Text type, but it can not work in this
case because it encodes the value as a text, while the parameters is
uuid. I can not use zero.UUID, because it is a [16]byte array, while i
have it in a string.
Thus, had to create my own ZeroNullUUID type that use a string as a base
but encodes it as a UUID.
This is the image that is shown at the home page, and maybe other pages
in the future. We can not use a static file because this image can be
changed by the customer, not us; just like name and description.
I decided to keep the actual media content in the database, but to copy
this file out to the file system the first time it is accessed. This is
because we are going to replicate the database to a public instance that
must show exactly the same image, but the customer will update the image
from the private instance, behind a firewall. We could also synchronize
the folder where they upload the images, the same way we will replicate,
but i thought that i would make the whole thing a little more brittle:
this way if it can replicate the update of the media, it is impossible
to not have its contents; dumping it to a file is to improve subsequent
requests to the same media.
I use the hex representation of the media’s hash as the URL to the
resource, because PostgreSQL’s base64 is not URL save (i.e., it uses
RFC2045’s charset that includes the forward slash[0]), and i did not
feel necessary write a new function just to slightly reduce the URLs’
length.
Before checking if the file exists, i make sure that the given hash is
an hex string, like i do for UUID, otherwise any other check is going
to fail for sure. I moved out hex.Valid function from UUID to check for
valid hex values, but the actual hash check is inside app/media because
i doubt it will be used outside that module.
[0]: https://datatracker.ietf.org/doc/html/rfc2045#section-6.8
I really doubt that they are going to use more than a single company,
but the application is based on Numerus, that **does** have multiple
company, and followed the same architecture and philosophy: use the URL
to choose the company to manage, even if the user has a single company.
The reason i use the slug instead of the ID is because i do not want to
make the ID public in case the application is really used by employees
of many unrelated companies: they need not need to guess how many
companies there are based on the ID.
I validate this slug to be a valid UUID instead of relaying on the
query’s empty result because casting a string with a malformed value to
UUID results in an error other than data not found. Not with that
select, but it would fail with a function parameter, and i want to add
that UUID check to all functions that do use slugs.
I based uuid.Valid function on Parse() from Google’s uuid package[0]
instead of using regular expression, as it was my first idea, because
that function is an order of magnitude faster in benchmarks:
goos: linux
goarch: amd64
pkg: dev.tandem.ws/tandem/numerus/pkg
cpu: Intel(R) Core(TM) i5-6200U CPU @ 2.30GHz
BenchmarkValidUuid-4 36946050 29.37 ns/op
BenchmarkValidUuid_Re-4 3633169 306.70 ns/op
The regular expression used for the benchmark was:
var re = regexp.MustCompile("^[a-fA-F0-9]{8}-[a-fA-F0-9]{4}-4[a-fA-F0-9]{3}-[8|9|aA|bB][a-fA-F0-9]{3}-[a-fA-F0-9]{12}$")
And the input parameter for both functions was the following valid UUID,
because most of the time the passed UUID will be valid:
"f47ac10b-58cc-0372-8567-0e02b2c3d479"
I did not use the uuid package as is, even though it is in Debian’s
repository, because i only need to check whether the value is valid,
not convert it to a byte array. As far as i know, that package can not
do that.
Adding the Company struct into auth was not my intention, as it makes
little sense name-wise, but i need to have the Company when rendering
templates and the company package has templates to render, thus using
the company package for the Company struct would create a dependency
loop between template and company. I’ve chosen the auth package only
because User is also there; User and Company are very much related in
this application, but not enough to include the company inside the user,
or vice versa, as the User comes from the cookie while the company from
the URL.
Finally, had to move methodNotAllowed to the http package, as an
exported function, because it is used now from other packages, namely
campsite.
[0]: https://github.com/google/uuid
jordi fita mas