IRB: last return value

In a nutshell: return statements inside blocks cause a method's return value to change. This is by design (and probably not even new ...

As you know, assignable_values does not invalidate a record even when an attribute value becomes unassignable. See this example about songs:

class Song < ActiveRecord::Base
  belongs_to :artist
  belongs_to :record_label

  assign...

MySQL's MIN and MAX functions are for aggregations only. This will not work and produce an error:

SELECT id, MIN(birthday, '1978-01-01') FROM users;

In order to compute the minimum or maximum value for the current row, use [LEAST...

Sometimes you need complex expectations on method arguments like this

SomeApi.should_receive(:find).with(:query => '*foo*', :sort => 'timestamp ASC', :limit => 100).and_return(['some result'])

This is not very flexible, and failure m...

Summary

• Use return to return from a method. return accepts a value that will be the return value of the method call.
• Use break to quit from a block and from the method that yielded to the block. break accepts a value that suppl...

On the Rails console, assigning an object to a variable can lead to this strange error (without stacktrace):

irb > recipient = Recipient.find(123)
Traceback (most recent call last):
TypeError (nil can't be coerced into Integer)
irb > recipi...

Checking if a JavaScript value is of a given type can be very confusing:

• There are two operators typeof and instanceof which work very differently.
• JavaScript has some primitive types, like string literals, that are not objects (as oppose...

PostgreSQL's array data type is pretty useful, but manipulating values of arrays can be awkward because of its syntax.

Consider the following users table which each example below will sta...

In Ruby on Rails, all objects have a useful blank? method. It returns true for nil but also for empty strings or empty arrays. Th...

The Angular 1.2 way:

# By default, angular returns undefined for invalid attributes which removes
# the value from the form field's ngModel (which means it's not sent to the
# server, and old values would not be overwritten).
#
# This directi...