I am much too tired to go into details, probably because I left the office at 11:15pm, but I finally finished a feature. It doesn't even sound like a particularly large or complicated feature. It sounds like a simple, 1-2 day feature until you look at it closely.

It took me an entire fucking week. and all the while I was coaching a junior dev who had just picked up Rails and was building something very similar.

It's the model, controller, and UI for creating a parent object along with 0-n child objects, with default children suggestions, a fancy ui including the ability to dynamically add/remove children via buttons. and have the entire happy family save nicely and atomically on the backend. Plus a detailed-but-simple listing for non-technicals including some absolutely nontrivial css acrobatics.

After getting about 90% of everything built and working and beautiful, I learned that Rails does quite a bit of this for you, through `accepts_nested_params_for :collection`. But that requires very specific form input namespacing, and building that out correctly is flipping difficult. It's not like I could find good examples anywhere, either. I looked for hours. I finally found a rails tutorial vide linked from a comment on a SO answer from five years ago, and mashed its oversimplified and dated examples with the newer documentation, and worked around the issues that of course arose from that disasterous paring.

like.
I needed to store a template of the child object markup somewhere, yeah? The video had me trying to store all of the markup in a `data-fields=" "` attrib. wth? I tried storing it as a string and injecting it into javascript, but that didn't work either. parsing errors! yay! good job, you two.

So I ended up storing the markup (rendered from a rails partial) in an html comment of all things, and pulling the markup out of the comment and gsubbing its IDs on document load. This has the annoying effect of preventing me from using html comments in that partial (not that i really use them anyway, but.)

Just.
Every step of the way on building this was another mountain climb.
* singular vs plural naming and routing, and named routes. and dealing with issues arising from existing incorrect pluralization.
* reverse polymorphic relation (child -> x parent)
* The testing suite is incompatible with the new rails6. There is no fix. None. I checked. Nope. Not happening.
* Rails6 randomly and constantly crashes and/or caches random things (including arbitrary code changes) in development mode (and only development mode) when working with multiple databases.
* nested form builders
* styling a fucking checkbox
* Making that checkbox (rather, its label and container div) into a sexy animated slider
* passing data and locals to and between partials
* misleading documentation
* building the partials to be self-contained and reusable
* coercing form builders into namespacing nested html inputs the way Rails expects
* input namespacing redux, now with nested form builders too!
* Figuring out how to generate markup for an empty child when I'm no longer rendering the children myself
* Figuring out where the fuck to put the blank child template markup so it's accessible, has the right namespacing, and is not submitted with everything else
* Figuring out how the fuck to read an html comment with JS
* nested strong params
* nested strong params
* nested fucking strong params
* caching parsed children's data on parent when the whole thing is bloody atomic.
* Converting datetimes from/to milliseconds on save/load
* CSS and bootstrap collisions
* CSS and bootstrap stupidity
* Reinventing the entire multi-child / nested params / atomic creating/updating/deleting feature on my own before discovering Rails can do that for you.

Just.
I am so glad it's working.
I don't even feel relieved. I just feel exhausted.

But it's done.
finally.

and it's done well. It's all self-contained and reusable, it's easy to read, has separate styling and reusable partials, etc. It's a two line copy/paste drop-in for any other model that needs it. Two lines and it just works, and even tells you if you screwed up.

I'm incredibly proud of everything that went into this.
But mostly I'm just incredibly tired.

Time for some well-deserved sleep.

(1) Datetimes. Seriously, fuck 'em.

(2) Everybody always thinking: Come on, that little feature is so simple. It couldn't possibly take a whole week to develop.

(3) Nobody really caring or understanding or forgetting after you've told them that if you cut corners and do something the dirty way, it adds to the effort and time needed to maintain or build new features.

Ok now I'm gonna tell you about my "Databases 2" exam. This is gonna be long.

I'd like to know if DB designers actually have this workflow. I'm gonna "challenge" the reader, but I'm not playing smartass. The mistakes I point out here are MY mistakes.

So, in my uni there's this course, "Databases 2" ("Databases 1" is relational algebra and theoretical stuff), which consist in one exercise: design a SQL database.

We get the description of a system. Almost a two pages pdf. Of course it could be anything. Here I'm going to pretend the project is a YouTube clone (it's one of the practice exercises).

We start designing a ER diagram that describes the system. It must be fucking accurate: e.g. if we describe a "view" as a relationship between the entities User and Video, it MUST have at least another attribute, e.g. the datetime, even if the description doesn't say it. The official reason?

"The ER relationship describes a set of couples. You can not have two elements equal, thus if you don't put any attribute, it means that any user could watch a video only once. So you must put at least something else."

Do you get my point? In this phase we're not even talking about a "database", this is an analysis phase.

Then we describe the type dictionary. So far so good, we just have to specify the type of any attribute.

And now... Constraints.
Oh my god the constraints. We have to describe every fucking constraint of our system. In FIRST ORDER LOGIC. Every entity is a set, and Entity(e) means that an element e belongs to the set Entity. "A user must leave a feedback after he saw a video" becomes like

For all u,v,dv,df,f ( User(u) and Video(v) and View(u, v, dv) and feedback(u, v, f) ) ---> dv < df

provided that dv and df are the datetimes of the view and the feedback creation (it is clear in the exercise, here seems kinda cryptic)

Of course only some of the constraints are explicitly described. This one, for example, was not in the text. If you fail to mention any "hidden" constraint, you lose a lot of points. Same thing if you not describe it correctly.

Now it's time for use cases.
You start with the usual stickman diagram. So far so good.
Then you have to describe their main functions.

In first order logic. Yes.

So, if you got the point, you may think that the following is correct to get "the average amount of feedback values on a single video" (1 to 5, like the old YT).
(let's say that feedback is a relationship with attribute between User and Video

getAv(Video v): int
Let be F = { va | feedback(v, u, va) } for any User u
Let av = (sum forall f in F) / | F |
return av

But nope, there's an error here. Can you spot it (I didn't)?

F is a set. Sets do not have duplicates! So, the F set will lose some feedback values! I can not define that as a simple set!

It has to be a set of couples, like (v, u), where v is the value and u the user; this way we can have duplicate feedback values in our set.

This concludes the analysis phase. Now, the design.

Well we just refactor everything we have done until now. Is-a relations become relationships, many-to-many relationships get an "association entity" between them, nothing new.
We write down on paper every SQL statement to build any table, entity or not. We write down every possible primary key or foreign key. The constraint that are not natively satisfied by SQL and/or foreign keys become triggers, and so on.

This exam is considered the true nightmare at our department. I just love it.

Now my question is, do actually DB designers follow this workflow? Or is this just a bloody hard training in Pai Mei style?

Another day, another datetime conversion problem.

Another day, another struggle with time zones.

How many fucking helper methods do I need to create for dates and time zones? How many components, pipes and services do I need to wrap just so two datetimes line up? Apparently another one today. At this point I'm ready to accept flat earth theory if it means no more time zones. I'm fucking sold on it if so.

It's not even the time zone that's the issue. It's business needing it formatted, but also offset properly, based on your browser locale, but with points that cross into DST observing time zones of a different locale simultaneously. Sometimes those times are the same, sometimes they're different, sometimes they're different but only in winter. And despite a plethora of libraries to help with these calculations, nothing ever seems to just work out of the box. So here's to another layer of abstraction, because time zones (and DST) are bullshit.