Recent notes
RSS feedMethod moved in 2.1 and again in 3.0 (beta)
It was moved from and back to Module#alias_method_chain
Re: IE GOTCHA
@insane-dreamer
That has nothing to do with IE. When you specify :cache => true you are saying that the files referenced should be saved to a file called all.js. When the script encounters the next line, it will overwrite the same file with the new contents.
Caching is not compressing, it doesn’t make sense to do with individual files, but it can make sense some times. I someone wants to do it, just specify a name for the cached file:
javascript_include_tag 'layout', 'typography', :cache => 'base' javascript_include_tag 'admin/layout', 'admin/extras', :cache => 'admin'
Separator default is not always "." but depends on locale
Locale en:
number_with_precision(111.2345) # => 111.235
Locale fr-FR:
number_with_precision(111.2345) # => 111,235
Same with delimiter.
Destroying Data
As far as I can tell, at least on a migration of a column from an integer to a decimal, this does not get rid of existing data.
Rails v2.1.0 has built-in time-zone support
Rails versions as of 2.1.0 have basic timezone support built-in to the Time object. However, to get a list of all the timezones you need to install the tzinfo gem.
TZInfo::Country.all.sort_by { |c| c.name }.each do |c| puts c.name # E.g. Norway c.zones.each do |z| puts "\t#{z.friendly_identifier(true)} (#{z.identifier})" # E.g. Oslo (Europe/Oslo) end end
TZInfo::TimeZone.get(identifier) returns a TimeZone -object by the identifier.
Common use
I typically use require_dependency when developing a class or module that resides in my rails app, perhaps in the lib/ dir. A normal require statement does not reload my changes, so I use require_dependency in files that reference my newly developed class or module.
Takes array
Like assert_difference this method can take an array of expressions to evaluate all of them. For example:
assert_no_difference ['Publisher.count', 'User.count', 'Membership.count'] do post :create end
It creates an assertion for each item in the array. So this will add three assertions to your test.
can return nil
I was surprised to get nil back when the right hand side (RHS) was nil. (I was expecting an exception.)
>> "abc" <=> nil => nil
Looking at the source I find you’ll get nil back in several cases when the RHS isn’t a string.
-
If the RHS doesn’t implement to_str.
-
If the RHS doesn’t implement <=>.
Assuming the RHS does implement to_str and <=>, the code delegates to the RHS and negates the result:
return - (rhs <=> self)
Can operate for both key and value for Hash
If you need to process both key and value of the Hash:
>> {"a" => "aa", "b" => "bb", "c" => "cc"}.collect {|k,v| [k,k+v]} => [["a", "aaa"], ["b", "bbb"], ["c", "ccc"]]
authenticity_token
<div style=“margin:0;padding:0”>
<input name="authenticity_token" type="hidden" value="f755bb0ed134b76c432144748a6d4b7a7ddf2b71" />
</div>
Helper generates a div element with a hidden input inside. This is a security feature of Rails called cross-site request forgery protection and form helpers generate it for every form whose action is not “get”.
Doesn't handle nested hashes
If you pass something like this:
http.set_form_data({:a => {:b => :c}})
it will completely mangle the value. So don’t use it.
Accessing controller data
You can access controller attributes from views via the @controller variable.
It has some important attributes:
-
@controller.controller_name -> the name of the controller
-
@controller.request -> returns the ActionController::Request
-
@controller.request.method -> the request method ( get, post, put, delete )
-
@controller.request.host -> the request host ( ip address or hostname ) where your server runs
-
@controller.request.ip -> the ip where your browser runs
-
how I use it
def rescue_action_in_public(exception)
case exception when ActiveRecord::RecordNotFound, ActionController::UnknownAction, ActionController::RoutingError redirect_to errors_path(404), :status=>301 else redirect_to errors_path(500) end
end
multiple attributes with the same validations
You can list multiple attributes if they share the same validations
validates :title, :body, :presence => true
sending the attributes as an array will return an error
validates [:title, :body], :presence => true #=> ArgumentError: Attribute names must be symbols
Careful when updating foreign key directly
Seems when you change key directly it doesn’t update association automatically.
>> chicken = Chicken.first >> chicken.head => old_head >> chicken.head_id = new_head.id >> chicken.head => old_head
Easy (stupid?) way to fix it:
class Chicken def head_id=(value) self.head = Head.find_by_id(value) end end
writes the file to disk even if you pass a block
I was surprised to find that the local file is opened and written even if you pass the block. If you’re local working directory isn’t writeable or doesn’t have the space, you’re out of luck.
writes the file to disk even if you pass a block
I was surprised to find that the local file is opened and written even if you pass the block. If you’re local working directory isn’t writeable or doesn’t have the space, you’re out of luck.
Add requires!
Useful for methods that take options = {}
class Hash def requires!(*params) params.each do |param| raise ArgumentError.new("Missing required parameter: #{param}") unless self.has_key?(param) end end end
keys to/from symbols
There’s probably a more effecient way to do this…
class Hash def keys_to_strings res = {} self.keys.each do |k| if self[k].is_a?(Hash) res[k.to_s] = self[k].keys_to_strings else res[k.to_s] = self[k] end end return res end def keys_to_symbols res = {} self.keys.each do |k| if self[k].is_a?(Hash) res[k.to_sym] = self[k].keys_to_symbols else res[k.to_sym] = self[k] end end return res end end
Positioning the column. MySQL only
Add support for MySQL column positioning via #add_column and #change_column
add_column and change_column in the MySQL adapter now accept some additional options:
:first => true # Put the column in front of all the columns
:after => column_name # Put the column after ‘column_name’
class AddLastNameToUsers < ActiveRecord::Migration def self.up add_column :users, :last_name, :after => :first_name end def self.down remove_column :users, :last_name end end
or
class AddIdToUsers < ActiveRecord::Migration def self.up add_column :urers, :id, :first => true end def self.down remove_column :users, :id end end
No security
One important thing to remember is that this is NOT hidden in the source code and can be modified by an evil user so all input in a hidden field should be considered as untrustworthy and checked just like a visible field.
database exceptions will still be raised
Note that save() only returns false on validation errors (when valid? returns false). If other errors occur at the database level, like a database deadlock or trying to insert null into a column that doesn’t allow it, that will still raise an exception.
Testing Net:HTTP connections
You can use this excellent library to stub Net:HTTP connections in your automatic tests:
Naming fragment cache
One of the common ways of using fragment caching is to cache content that’s shared across the site (eg. left navigation, menus, widgets etc.) that looks and works the same regardless of the name of the action or controller calling it. In such cases it’s very easy to just use named fragment caching eg.:
<% cache('left_nav') do -%> <%= display_left_nav -%> <% end -%>
Use :path_prefix for the namespace
Resources are added after the :path_prefix. However if you use a :path_prefix on a resource, it overrides the namespace path instead of appending to it (as I think it should).
Here is what I wrote to create a versioned API access path.
map.namespace :api3, :path_prefix=>"/api/v3" do |api| api.resources :posts api.resources :comments, :path_prefix=>"/api/v3/post/:post_id" end
This will create routes like
path: /api/v3/posts/1 named_route: api3_post() controller=>"api3/posts"
Prevent transactional fixtures for a specific test class
If you want to prevent a specific group of tests from being run inside a transaction, just define inside your test class the methods teardown_fixtures and setup_fixtures with empty bodies.
Prevent transactional fixtures for a specific suite
If you want to prevent a specific group of tests from being run inside a transaction, just define inside your test class the methods teardown_fixtures and setup_fixtures with empty bodies.
Looking for "to the power of"?
If you’re trying to calculate 2 to the power of 2, the ^ method is not what you want. Try ** instead.
2^2 #=> 0 2^8 #=> 10 2**2 #=> 4 2**8 #=> 256
How using Array methods
It’s not possible to use Array methods with a scope because it’s not an Array but an ActiveRecord::NamedScope::Scope :
this
Article.promotion.sum(&:price)
doesn’t run.
But you can use the to_a method to transform the ActiveRecord::NamedScope::Scope to an Array :
Article.promotion.to_a.sum(&:price)