LoDash: isBlank and isPresent mixins
When you need to check a value for presence, don't rely on JavaScript since it considers 0 or "0" false. Also don't rely on LoDash's _.isEmpty:
if ('0') { ... } // false
if (0) { ... } // false
if (!_.isEmpty('0')) { ... } // true (= good)
if (!_.isEmpty(0)) { ... } // false (= not good)
This is because isEmpty it is only meant for objects with a length.
While the name implies that it's meant only for collections, you probably still want something like isBlank or `is…
Recommended git workflow for feature branches
This is a guide on how to effectively use git when working on a feature branch. It is designed to get out of your way as much as possible while you work, and ensure you end up with clean commits in the end.
We assume you are the only person working on this branch. We also assume the branch has never been "partially" merged into master.
You want to start a feature branch
git checkout master
git checkout -b my-feature-branch
git push -u
You've added code that works independently of your other …
Careful when using database locks in transactions
We tend to use database transactions as a magic bullet to get rid of all our concurrency problems. When things get really bad, we might even throw in some locking mechanism, but then are usually done with it.
Unfortunately, transactions semantics in databases are actually very complicated, and chances are, your making some incorrect assumptions.
The MySQL innodb engine actually has [four different modes](ht…
A common mistake in validations using regular expressions
You certainly use regular expressions for validating strings, e.g. e-mail addresses by saying
validate :email, :with => /.../
Such regular expressions often look something like the following: /^[\w+\-.]+@[a-z\d\-.]+\.[a-z]+$/i which perfectly matches as expected:
>> "foo.bar-ooops@bar.com".match /^[\w+\-.]+@[a-z\d\-.]+\.[a-z]+$/i
=> #<MatchData "foo.bar-ooops@bar.com">
… and does not match unwanted values:
?> "invalid email@invalid host.com".match /^[\w+\-.]+@[a-z\d\-.]+\.[a-z]+$/i
=> nil
I know that the express…
Auto-squashing Git Commits
git command line options for automating common rebasing tasks, like adding a fix to a commit that was already rebased into the history.
Inspecting a live Ruby process
How to get a backtrace from a running ruby process:
Rails: Overwriting default accessors
All columns of a model's database table are automagically available through accessors on the Active Record object.
When you need to specialize this behavior, you may overwrite the default accessors (using the same name as the attribute) and call read_attribute(attr_name) and write_attribute(attr_name, value) to actually change things. Example:
class Poet < ActiveRecord::Base
def name=(name)
write_attribute(:name, name.strip)
end
end
See also
- [Why belongs_to/has_many cannot overwri…
Use "overflow: hidden" to avoid floating elements from wrapping a container's text
Consider this HTML:
<div id="container">
<div id="actions">
<a href="#">Click me!</a>
</div>
<div id="content">
Hello Universe! Hello Universe! Hello Universe! Hello Universe! Hello Universe! Hello Universe!
</div>
</div>
If you want the actions element to float on the left, you'd just say this in your CSS:
#actions { float: left; }
Unfortunately, any content of the content's text will wrap underneath it:
 top/left.
- Relative to the document top/left.
It’s important to understand the difference and which type is where.
Custom error pages in Rails 3.2+
Starting with Rails 3.2, there is a nicer way to display custom error pages (i.e. "page not found") that does not interfere with ExceptionNotifier. (I'm not sure about Airbrake et al.)
José Valim has posted this on his blog, here is a slightly more verbose rundown:
-
Register your own app as the application responsible for showing error pages by adding
config.exceptions_app = self.routesto your
config/application.rb. -
Add rout…