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Materialized Views in Postgres

https://hashrocket.com/blog/posts/materialized-view-strategies-using-postgresql

#postgres #sql

Custom column types in Sequel

http://sequel.jeremyevans.net/rdoc/files/doc/schema_modification_rdoc.html#label-Column+types

We made a custom postgres domain named ‘timezone’. To use it:

column :timezone, ‘timezone’

#sequel #postgres #domain

3 Things I Learned Today

- relearned the ~> syntax in Gemfiles

- RabbitMQ runs on Erlang VM (!)

- I’m still holding onto some of that perspective I always get after coming back from Burning Man. Like, “oh wow I’m thinking this way. That’s interesting to observe.”

#3thingsilearnedtoday

Sequel and Postgres time

Trying to have app use database time for everything. Sequel gem docs make it straight forward, of course not in this app. Looking to pull the CURRENT_TIMESTAMP value out of Postgres and use it as a time object in Rails. The code:

Sequel::Model.db.get(Sequel.CURRENT_TIMESTAMP)

This returns a Time class object, and you can do all the normal stuff to it (ie. .to_f, .to_datetime, etc) that you’d expect work.

Now to deal with all the broken tests that use Timecop, because Timecop doesn’t freeze our custom Clock object that pulls database time.

#sequel #postres #current_timestamp #rails

Undo anything in git

https://github.com/blog/2019-how-to-undo-almost-anything-with-git

#git #til

Wrangling with a JavaScript text parser that identifies certain tags and can toggle url shortening. Used lots of other places so it has a ton of extra complexity that makes it difficult to understand immediately.

One of those things where you’d love to rewrite it just to feel better about not having something so messy. But is it worth the cost? Usually no.

#coupling #til

Overriding primary key in Rails

http://ruby-journal.com/how-to-override-default-primary-key-id-in-rails

Depends how far you want to take it. But basic idea is that a primary key is really only a key with non null and unique constraints. There’s a syntax for doing that in migrations (not null) and with a custom index (unique constraint). Then make sure you define self.primary_key in your model. Lastly set the param in the routes file so you can do params[:name]. Don’t override the #id methods for your model, too many other Rails methods rely on them.

#til #rails #primary_key

If you’re mocking out a method, such that you’re isolating it’s behavior from hitting an external service (database, etc), you may need to just duplicate the entire logic inside the method with mocks and doubles.

Felt a bit wrong, like I was duplicating logic. But it isolates the method. Maybe there’s an even better way I will learn some day.

#rpsec #testing #mocks #isolation

3 Things I Learned Today

1. Turing Machine and lambda calculus (Jim Weirich talk)

2. Better feel for using map and reduce

3. ???

#til

Ruby Named Parameters / Keyword Arguments

It’s 2015 and I’m just now seeing code like this in the wild?!?:

def some_method(first_name:, last_name:)

Keyword arguments were added in Ruby 2.0, this particular syntax (no default values) is Ruby 2.1. Released end of Dec 2013.

https://robots.thoughtbot.com/ruby-2-keyword-arguments

#ruby #named params #keyword arguments

Count number of arithmetic sequences in an array

“Arithmetic” means, from an array with at least 3 values, the difference from one value to the next one remains the same.

eg. [-1,1,3, 5] is arithmetic. [-1,1, 3, 3] is not.

First attempt under the gun of a timed challenge took an hour, almost had a working solution. Code deleted.

Second attempt a few days later, <30 min. Solved. Some recursiveness thrown in there.

#recursion #code challenges

You can make Mocks more than just an empty object

Say you’re testing a class. It takes a collection of other objects at initialization, and there’s a class method making a call to the collection to return a subset of objects.

Instead of building out actual objects, you can build mocks that will respond to any methods you want. Can even have a method return other mocks.

Vague for anyone reading this, but it will jog my mind for the specific example.

#til #mocks #rspec

“The world breaks everyone and afterward many are strong at the broken places.” Ernest Hemingway

The world is breaking me right now.

URI encoding

Let’s say you’re trying to build url strings from a list of names, to then query the Battle.net World of Warcraft API. Let’s say some of those names have non-ASCII characters, names like ‘Doomsday’, etc.

Ruby’s open-uri gem complains hard if characters like this are not encoded correctly.

A simple URI.encode(’CrāzyNaméHére’) gets it done.

#ruby #uri #open-uri #string #encoding

Thoughtbot Playbook

playbook.thoughtbot.com

Basically how they do their entire business. Great resource.

#thoughtbot #docs #process #playbook

Sublime Text - multi-line wrap with tag

Cmd - Shift - L

Ctrl - Shift - W

Type the tag of your choice.

Incredible.

http://www.thenerdary.net/post/29835955835/st2-wrap-each-line-in-an-element

#sublime text

JavaScript puzzle

Write a function that takes a seed number and returns a function, and with every successive call of that returned function it returns a a the value of the seed plus argument.

Vague and hard to explain. I had to ask a bunch of questions to clarify. Here's what he output would look like:

var a = getIterator(10); a(2); => 12 a(4); => 16;

After some monkeying around with explicit variable declarations, we arrived at this:

var a = getIterator(seed) { return function(num) { return seed += num; } };

So how the fuck does this work? Well, lots of assumptions made here about the code is actually be interpreted and executed. After reading about variable hoisting this is how I think it works:

1. getIterator runs only once. It returns the anonymous function defined within it.

2. Before that, because of function hoisting the anonymous function it returns is declared.

3. And before that, the variables are declared.

4. So all that shit runs, and a function with the seed saved in it is retuned and assigned to var a.

5. Now here's where I'm still having questions: how the fuck does the function store state from call to call?

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