Hack of the day: A reverse for Rails' &:
Ever wondered if there is a reverse for Rails' .each(&:to_s)
idiom? Turns out there is...
You probably already know, that you can abbreviate code like
dogs.each { |dog| dog.bark! }
with
dogs.each(&:bark!)
Now suppose it is the other way round and you have
bones.each { |bone| dog.eat!(bone) }
Good old Ruby already has a solution:
bones.each(&dog.method(:eat!))
Related cards:
Hack of the day: Find all classes that define a method with a given name
If (for some reason that you don't want to ask yourself) you need to know all classes that define a method with a given name, you can do it like this:
def classes_defining_method(method_name)
method_name = method_name.to_sym
Objec...
Security issues with hash conditions in Rails 2 and Rails 3
Find conditions for scopes can be given either as an array (:conditions => ['state = ?', 'draft']
) or a hash (:conditions => { 'state' => 'draft' }
). The later is nicer to read, but has horrible security implications in some versions of Ru...
Hack of the day: One-liner to run all Cucumber features matching a given string
The following will search for all .feature
files containing a search term and run them using geordi.
find features/ -name '*.feature' | xargs grep -li 'YOUR SEARCH TERM' | sort -u | tr '\n' ' ' | xargs ...
How to get the hostname of the current machine in Rails or a Ruby script
Use Socket.gethostname
. So for a machine whose hostname is "happycat", it will look like this:
>> Socket.gethostname
=> "happycat"
That should work right away for your Rails application. For plain Ruby, you first need to do:
requi...
Rails: render a template that accepts a block by using the layout option of render
Let's say you have a form that you render a few times but you would like to customize your submit section each time. You can achieve this by rendering your form partial as layout and passing in a block. Your template or partial then serves as the ...
Hack of the day: One-liner to run all changed Cucumber features
Similar to our snippet that runs all Cucumber features matching a given string, the following will run all modified or new Cucumber features by looking at your git status:
git status --short | grep -v '^ D ' | grep '.featur...
Creating the inverse of a Rails migration
Let's say you need to revert a migration that happened a while back. You'd create a new migration that removes what was added back then in the up
path, while its down
path restores the old functionality.
While you could just copy&paste the `d...
Github: How to find the Readme for a certain version of a gem
When a gem author releases a new version to Rubygems, usually a tag with the version number (e.g. v1.2.0
) is created an pushed to Github, so everyone can check out or take a look at the source code at this point version release at a later time.
...
How to build the perfect number of blank records for a nested form
When you render a nested form for a Movie
which has_many :actors
, you want to render the right number of blank Actor
forms. The right number means:
- A minimum number of blank forms so the user can add more
Actors
to an existingMovie
, ...
Extracting the conditions of a named scope in Rails 2.3
See attached link for a way to extract the conditions of a named scope in Rails 2.3.