TIL

The rails generate (g) command is useful for quickly creating the building blocks of a Rails app. Until you misspell or otherwise mess up a command: % rails g model blurg_post invoke active_record create db/migrate/20151006162244_create_blurg_posts.rb create app/models/blurg_post.rb invoke rspec create spec/models/blurg_post_spec.rb ‘Blurg post’? I meant ‘blog post’. Luckily, we can remove those auto-generated files as fast as we created them, with destroy (d). % rails d model blurg_post invoke active_record remove db/migrate/20151006162244_create_blurg_posts.rb remove app/models/blurg_post.rb invoke rspec remove spec/models/blurg_post_spec.rb http://edgeguides.rubyonrails.org/command_line.html#rails-destroy

At the end of each day, I try to record what I did, to jog my memory during the next morning’s standup. This is a helpful aid: git log --since="24 hours ago" I SSH into my work machine and run this in my project’s root directory. Combined with an alias from the Hashrocket Dotmatrix, glg (git log --graph --oneline --decorate --color --all), I get a terse summary of the day’s work, ready to be pasted into your note-taking or project management tool of choice: ...

It’s important to fetch Ruby environmental variables rather than directly referencing them. This code depends on ‘secret_key’: key = ENV['secret_key'] When ‘secret_key’ is not set, ‘key’ will be assigned nil, which is an object. Later, a call to key.upcase will produce a NoMethodError, because Ruby doesn’t know how to uppercase nil. This is better: key = ENV.fetch('secret_key') Now, when ‘secret_key’ is not set, KeyError will be raised. The code fails fast. fetch takes a second argument as a default, which means you can even prevent KeyError entirely, if you choose. ...

‘Random’ numbers in Go don’t always seem random. This is because the rand package defaults to a seed of 1. That’s great if you need a bunch of random numbers at the start of your program. Not great if you expect a different outcome each time you run the program. A solution is to seed rand with Unix time. Try it in the init() function: package main import ( "math/rand" "time" ) func init() { rand.Seed(time.Now().UTC().UnixNano()) } ...

Want to build URLs with JavaScript? Try thewindow.location object. This came from a React.js project we’re working on. It uses ES6 template string interpolation, which isn’t necessary but definitely is nice: `${window.location.protocol}//${window.location.host}/posts/${this.props.postID}/edit` Which becomes: "https://secret-project.com/posts/42/edit"

Using a Postgres table for caching? You might want to try making it unlogged. unlogged tables are not written to the write-ahead log, which makes them much faster. This also means they are not crash-safe, and are truncated when a crash or unclean shutdown occurs. For caching purposes, that’s likely to be an acceptable tradeoff. Documentation

Go has an interesting feature called iota. When declaring a list of constants, this keyword represents successive untyped integer constants. const ( foo = iota // foo == 0 bar = iota // bar == 1 baz = iota // baz == 2 ) Anytime const is invoked, the counter resets. const foo = iota // foo == 0 const bar = iota // bar == 0 This is a cool way to quickly define a list of integer constants, such as ’true’ and ‘false’, for later use.

Ruby has a nice percent string literal for regular expressions, %r. It’s like // but allows your regex to contain backslashes without escaping them. Check it out: 2.1.0 :001 > 'http://google.com'.gsub(/http:\/\/google.com/, 'fine') => "fine" 2.1.0 :002 > 'http://google.com'.gsub(%r{http://google.com}, 'better') => "better" As the example implies, this is useful when matching URLs. Documentation

You can store a SQL query with prepare. db=# prepare posts_search as select title from posts limit 5; PREPARE Call the method with execute. db=# execute posts_search; title ----------------------------------- Hello World! My First Pull Request: HAML My First Pull Request: Sinatra My First Pull Request: Capistrano My First Pull Request: SASS (5 rows) Deallocate the query with deallocate, and you can set it again. db=# deallocate posts_search; DEALLOCATE db=# prepare posts_search as select title from posts limit 10; PREPARE

Want to change database connections from inside psql? You can! Psql, the REPL for Postgres, has a useful meta-command called \connect, or \c. This lets you establish a new connection to a Postgres server, while closing the current connection. Here is the required format: \c or \connect [ dbname [ username ] [ host ] [ port ] ] | conninfo Only \c [my_database] is required; omitted parameters are taken from the previous connection. ...