Had to do a couple of changes to the database: add the currency_code to
the payment relation, to format the price according to the payment’s
currency instead of the company’s; and the reference SQL function, to
replace the equivalent golang function, so that i can use it to index
payments.
The rest is mostly the same as any other page, except that the
individual payment’s page is not a form, but a regular info dump.
I also moved the payment settings as a sub-route of payments, as i
believe this makes more sense than an additional user menu item.
Customer wants to require a down payment of 30 % for bookings made
one week or more before the actual date, and to make the full payment
otherwise.
This would require yet another relation to keep these values. Fuck it;
i added them to the function, as they are very unlikely to change.
That forced me to change the test for draft_payment to use relative
dates, otherwise there is no way i can have stable results in the
future.
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.
I had to add the payment concept separate from the booking, unlike other
eCommerce solutions that subsume the two into a single “order”, like
WooCommerce, because bookings should be done in a separate Camper
instance that will sync to the public instance, but the payment is done
by the public instance. There will be a queue or something between
the public and the private instance to pass along the booking
information once the payment is complete, but the public instance still
needs to keep track of payments without creating bookings.
To compute the total for that payment i had to do the same as was doing
until now for the cart. To prevent duplications, or having functions
with complex return types, i now create a “draft” payment while the
user is filling in the form, and compute the cart there; from Go i only
have to retrieve the data from the relation, that simplifies the work,
actually.
Since the payment is computed way before customers enter their details,
i can not have that data in the same payment relation, unless i allow
NULL values. Allowing NULL values means that i can create a payment
without customer, thus i moved all customer details to a separate
relation. It still allows payment without customer, but at least there
are no NULL values.
Draft payments should be removed after a time, but i believe this needs
to be done in a cronjob or similar, not in the Go application.
To update the same payment while filling the same booking form, i now
have a hidden field with the payment slug. A competent developer would
have used a cookie or something like that; i am not competent.
Customer told us that there are some options, such as towels, that have
a fixed price for the whole stay, not a per night price. Thus, had to
add a boolean to know whether to use sum or max when computing the
cart’s total for each option.
It is a separate relation, instead of having a field in campsite_type,
because not all campsite types allow dogs. I could have added a new
field to campsite_type, but then its values it would be meaningless for
campsites that do not allow dogs, and a nullable field is not a valid
solution because NULL means “unknown”, but we **do** know the price —
none.
A separate relation encodes the same information without ambiguities nor
null values, and, in fact, removed the dogs_allowed field from
campsite_type to prevent erroneous status, such as a campsite type that
allows dogs without having a cost — even if the cost is zero, it has to
be added to the new relation.
Besides the dynamic final cart, that was already handled by HTMx, i had
to check the maximum number of guests, whether the accommodation allows
“overflow”, whether dogs are allowed, and that the booking dates were
within the campground’s opening and closing dates.
I could do all of this with AlpineJS, but then i would have to add the
same validation to the backend, prior to accept the payment. Would not
make more sense to have them in a single place, namely the backend? With
HTMx i can do that.
However, i now have to create the form “piecemeal”, because i may not
have the whole information when the visitor arrives to the booking page,
and i still had the same problem as in commit d2858302efa—parsing the
whole form as is would leave guests and options field empty, rather than
at their minimum values.
One of the fieldsets in that booking form are the arrival and departure
dates, that are the sames we use in the campsite type’s page to
“preselect” these values. Since now are in a separate struct, i can
reuse the same type and validation logic for both pages, making my
JavaScript code useless, but requiring HTMx. I think this is a good
tradeoff, in fact.
I have to ask number and age ranges of hosts of guests for all campsite
types, not only those that have price options for adults, children, etc.
because i must compute the tourist tax for adults. These numbers will
be used to generate de rows for guests when actually creating the
booking, which is not done already.
To satisfy the campsite types that do have a price per guest, not only
per night, i had to add the prices for each range in the
campsite_type_cost relation. If a campsite type does not have price
per person, then that should be zero; the website then does not display
the price.
The minimal price for any campsite type is one adult for one night,
thus to compute the price i need at least the campsite type, the dates,
and the number of adults, that has a minimum of one. I changed the
order of the form to ask for these values first, so i can compute the
initial price as soon as possible. To help further, i show the
<fieldset>s progressively when visitors select options.
jordi fita mas