Helpful Helpers

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Here is a list of helper methods that we use a lot at Plexus to make our jobs easier. A few have been referenced in previous posts, but I thought I'd list them all here in one place.

Strip text for pretty URLs

You can use this method to replace all non-alphanumeric characters to dashes in a title or name when you're including them in the URL.

This is the route I use for my posts on this blog:

            m.post_details ':year/:month/:day/:title', :action => "by_date",
              :requirements => { :year => /(19|20)\d\d/, :month => /[01]?\d/, :day => /[0-3]?\d/},
              :day => nil, :month => nil, :title => nil
            

And here is the helper to strip out characters in the title when creating the URL:

            # Replace all non-alphanumeric characters with dashes
            def strip_chars(string='')
              string.gsub(/\s+/,'-').gsub(/[^a-z0-9\-]+/i, '')
            end
            

You can call the helper when you generate the route.

            post_details_path(:year => @post.date.year, :month => @post.date.month, :day => @post.date.day, :title => strip_chars(@post.title))
            

Generate a random password of n length

I've actually got a whole other post for just this helper, but decided to include it in this list.

            def generate_password(length=6)
              chars = 'abcdefghjkmnpqrstuvwxyzABCDEFGHJKLMNOPQRSTUVWXYZ23456789'
              password = ''
              length.times { |i| password << chars[rand(chars.length)] }
              password
            end
            

It will generate a 6 digit password by default, but you can specify the desired length.

            generate_password
            => "Q6Kfze"
            
            generate_password(10)
            => "ZSJcmtRH5q"
            

Built-in rails helpers

These following helpers are built into rails, but you may not know about them.

Array#to_sentence

            ["this", "that", "the other"].to_sentence
            => "this, that, and the other"
            

number helpers

            number_to_currency(123456789)
            => "$123,456,789.00"
            
            number_to_human_size(123456789)
            => "117.7 MB"
            
            number_to_phone(1234567890, :area_code => true)
            => "(123) 456-7890"
            

There are a ton of string inflector helpers

            "under_scored".dasherize
            => "under-scored"
            
            "names_and_titles".humanize
            => "Names and titles"
            
            "lower case title".titleize
            => "Lower Case Title"
            

Tagged: helpers, rails, ruby

RESTful Routes Demystified

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RESTful application design is a rails-standard way to structure your CRUD actions. It simplifies your controllers into 7 actions: index, show, new, create, edit, update, and destroy. Here are some basics for working with RESTful routes.

The simple way to get the default routes:

            ActionController::Routing::Routes.draw do |map|
              map.resources :products
            end
            

Route Options

Several options can be passed to the route to customize it. You can use the path_prefix option to customize the appearance of your URLs. The name_prefix option is used to change the way the routes are called. The controller option is used to specify a custom controller.

            # start all of your URLs with /admin
            # '/admin/projects/:id/edit'
            map.resources :products, :path_prefix => '/admin'
            
            # start all of your routes with 'mng_'
            # mng_products_path or mng_product_path(:id)
            map.resources :products, :name_prefix => 'mng_'
            
            # if you want your URLs to say '/products/:id'
            # but your controller is called 'store_products'
            map.resources :products, :controller => 'store_products'
            

Adding Routes for Custom Actions

The resources method will generate the routes for the default REST actions, but what if you want to add your own actions to your controller? There are two options for adding custom routes: the member option is for routes that require an id to be passed, and the collection option is for actions that don't require an id. With each option, you must pass a hash with the action name and the HTTP method.

            # return_policy_products_path => '/products/return_policy'
            # submit_question_products_path => '/products/submit_question'
            map.resources :products, :collection => {:return_policy => :get, :submit_question => :post}
            
            # warranty_product_path(:id) => '/products/:id/warranty'
            map.resources :products, :member => {:warranty => :get}
            

Nested Routes

You can nest routes for objects that are related. Say the products have customer reviews with a has_many relationship. You can nest the resources call within the products route definition.

            # product_reviews_path(:product_id) => '/products/:product_id/reviews'
            # product_review_path(:product_id, :id) => '/products/:product_id/reviews/:id'
            # edit_product_review_path(:product_id, :id) => '/products/:product_id/reviews/:id/edit'
            map.resources :products do |products|
              products.resources :reviews, :controller => 'customer_reviews'
            end
            

Those are the basics, but there are a LOT more possibilities. If you're interested, there is a really great guide to all things routes.

Tagged: routes, rails

Working with the flash hash

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The flash hash is what Rails uses to display messages (both notices and errors). Since it's a Hash, you can assign any key/value pair that you want, but I tend to stick with flash[:notice] for a success message, and flash[:error] for an error message.

In my opinion, using the flash hash is a little confusing. I haven't come across a book or tutorial that fully explains how to control it properly. So, here are the options for using the flash hash in Rails.

flash[:key] and flash.now[:key]

The following method shows how to best use the flash hash:

            def create
              @user = User.new(params[:user])
              respond_to do |format|
                if @user.save
                  flash[:notice] = 'User was successfully created.'
                  format.html { redirect_to admin_users_path }
                else
                  flash.now[:error] = 'The user could not be created'
                  format.html { render :action => 'new' }
                end
              end
            rescue Exception => ex
              logger.warn('ERROR: ' + ex.message)
              flash.now[:error] = 'There was an error creating the user.'
              render :action => 'new'
            end
            

Notice that I use the flash hash in two different ways: flash[:key] and flash.now[:key]. The way I use it depends on when I want it displayed. The flash[:key] usage should only be used before redirection, because it makes the object available for the current action and the next action. The flash.now[:key] usage should be used when you only want the flash object to be available to the current action.

Here's an example why you shouldn't use flash[:key] without redirection. Let's say this is your controller:

            class MainController < ApplicationController
              def index
                flash[:notice] = 'Welcome to the site!'
              end
              
              def profile
              end
            end
            

When you visit the index page, you'll see the message 'Welcome to the site!.' If you then click a link from the index page that takes you to the profile page, you'll still see the message 'Welcome to the site!' because the flash[:key] is available to the current action and the next action.

Displaying the flash

Here is a really helpful method to display the contents of the flash hash that I modified from one of Ryan Bates' awesome Railscasts:

            <%- flash.each do |key, msg| -%>
            	<div id="<%= key %>">
            		<p style="float:right;"><%= link_to_function 'X', "Effect.Fade('#{key}')" %></p>
            		<p><%= msg %></p>
            		<div class="clear"></div>
            	</div>
            <%- end -%>
            

This method will loop through each key in your flash hash and create a div with the name of the key, then put the contents inside with a link to close the message div.

I put this method in a partial called _notice_div.html.erb and include it at the top of my application layout. Here are the styles I use for notices and errors:

            #notice { background-color: #A4E7A0; border: 1px solid #26722D; }
            #error { background-color: #F0A8A8; border: 1px solid #900; }
            #notice, #error { width: 90%; margin: 0 auto 10px auto; padding: 5px; }
            #notice p, #error p { margin-left: 20px; padding: 0; font-size: .75em; color: #000; }
            #notice a, #error a { text-decoration: none; padding: 0 3px; }
            #notice a { border: 1px solid #26722D; color: #26722D; }
            #error a { border: 1px solid #900; color: #900; }
            #notice a:hover, #error a:hover { color: #333; border: 1px solid #333; }
            

Tagged: css, rails, flash

Routes Demystified

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It took me a while to discover the full potential of Rails' routes. I slowly learned more and more neat stuff that made me like them more and more. They are extremely powerful and are very useful for URL re-writing. Following is all of my route knowledge. If you notice something that I didn't cover, please leave it in the comments.

A few basic routes:

            # this will route domain.com/ to the index action of your main controller
            map.connect '', :controller => 'main'
            
            # this will create a custom URL for your about-us page
            map.connect 'custom-url/about-us', :controller => 'about_us', :action => 'index'
            

Pay attention to the order of your routes in your routes.rb file. They are evaluated in order from top to bottom. Routes at the top will be used before routes at the bottom if they are too similar.

Named Routes

Instead of saying map.connect, let's get crazy and name our routes. I'll use the same routes as above and add a few.

            # you can now call this route with home_path or home_url
            map.home '', :controller => 'main'
            
            # call this route with about_us_path or about_us_url
            map.about_us 'custom-url/about-us', :controller => 'about_us', :action => 'index'
            
            # symbols in the routes define options you pass when calling the route
            # call product_details_path(:id => @product) to access this route
            map.product_details 'products/detail-view/:id', :controller => 'products', :action => 'show'
            # all-purpose route for the products controller : products_path(:action => 'search') or products_path(:action => 'buy', :id => product)
            map.products 'products/:action/:id', :controller => 'products'
            

Route Blocks Using with_options

If we have several routes for the same controller, it makes sense to use with_options to simplify the definitions.

            map.with_options :controller => 'news' do |m|
              m.news 'news-releases/list', :action => 'index' # news_path
              m.news_details 'news-releases/details/:id', :action => 'show' # news_details_path(:id => news_release)
              m.news_author 'news-releases/by-author/:name', :action => 'author' # news_author_path(:name => 'Bill')
            end
            

Better URLs with Routes

Routes are great for creating search engine friendly URLs. Supposed you'd like to add the title of your blog post to the URL.

            map.blog_details 'blog/details/:id/:title', :controller => 'blog', :action => 'show', :title => nil
            

Now you can call the blog_details path and give it the :id and :title as options for the URL. Also notice that I set :title => nil at the end of the route. This marks that option as optional for the route call.

            # this call will generate the following URL: http://domain.com/blog/details/1/My-First-Blog-Post
            # I'm using a helper method in this call entitled 'strip_chars', it is below
            blog_details_path(:id => post, :title => strip_chars(post.title)) %>
            
            # you can also omit the title when invoking the route because it is optional.
            # since your 'details' method will be using the :id parameter to find the record
            # we don't really need the title, it's just for search engines
            blog_details_path(:id => post) %>
            
            # this helper method takes a string, replaces all spaces with dashes, then strips out all non-letter, non-number, non-dashes
            # it's good for generating URL-friendly titles
            def strip_chars(string='')
              return '' if string.blank?
              string.gsub(' ','-').gsub(/[^a-z0-9\-]+/i, '')
            end
            

Caching and Pagination

If we cache our site, and certain actions show a paginated list, then we need to add the :page attribute to the route to ensure that the cache is recorded properly. After all, to our server /blog/list looks the exact same as /blog/list?page=2 when retrieving cached pages.

            map.blog 'blog/list/:page',
                     :controller => 'blog',
                     :action => 'list',
                     :requirements => {:page => /\d+/},
                     :page => nil
            # blog_path
            # blog_path(:page => 1)
            

Notice that we added something new, the :requirements option. For :page, it's a regular expression telling us the supplied value must be a number. I've also set :page => nil so that we don't always have to specify it when invoking the route.

One thing to watch out for when calling a paged route is to be careful when you're on another paged section of your site. Say I have the route above for blogs and a similar route for news releases. If I'm on the page /news/list/5 and I call blog_path it will take the :page parameter from the current URL and you'll end up on page 5 of your blog post list. Confused? Just make sure when you are calling a paged route to specify it as blog_path(:page => 1) to explicitly go to /blog/list/1 or call blog_path(:page => nil) to go to /blog/list. Both will work.

Route Conditions

Similar to RESTful routes, you can specify the method of the request with the :requirements option. While this is useful, it makes much more sense to just use map.resources to get real RESTful routes.

            map.connect 'blog-post/:id', :controller => 'blog', :action => 'show', :requirements => { :method => :get }
            map.connect 'blog-post/:id', :controller => 'blog', :action => 'update', :requirements => { :method => :post }
            
            # a GET method to /blog-post/1 will route to the 'show' action
            # a POST method to /blog-post/1 will route to the 'update' action
            

I think that's enough for normal routes. Hopefully soon I can write a post on RESTful routes, which are a whole different beast.

Tagged: rails, routes

Rails Tips

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While there are no shortages of posts listing tips for Rails, or lesser-known Ruby methods, I decided to write this post because these are shortcuts or helpers that I didn't know about until fairly recently. I'm going to try and update this post as I discover new railties and rubyisms along the way, so check back every now and then.

Symbol#to_proc

This is really a Ruby method, but it makes running a collect or map on ActiveRecord objects much easier. Whereas before, you would do this:

            @members = Member.find(:all).map { |member| member.name }
            

Now, you can simplify it to this:

            @members = Member.find(:all).map(&:name)
            

Model Calculations

This will let you do simple calculations on any ActiveRecord model (as long as the field you're calculating is numeric).

            Student.average(:grade) # finds the average grade for all students (returns a float)
            Student.maximum(:grade) # finds the highest grade
            Student.minimum(:grade) # finds the lowest grade
            Student.sum(:grade) # the sum of all grades
            

Custom ActiveRecord Associations

Let's say you have a model called BlogPost and one called Comment. A blog post has many comments, but you also have a boolean field on comments called approved that signifies if it's been decided that the comment is not spam (like most comments are). This is what your BlogPost model might look like:

            class BlogPost < ActiveRecord::Base
              has_many :comments
            end
            

You can add custom associations for approved_comments and unapproved_comments to your model to make fetching these comments a lot easier.

            class BlogPost < ActiveRecord::Base
              has_many :comments
              has_many :approved_comments, :class_name => 'Comment', :conditions => 'approved=1'
              has_many :unapproved_comments, :class_name => 'Comment', :conditions => 'approved=0'
            end
            

All you have to do is specify the class name of the associated model and the conditions of the find. This makes it possible to easily access these associations from within your views.

You can now show the number of approved comments for each post.

            <%= @blog_post.title %> - <%= @blog_post.approved_comments.count %> Comments
            

You can also easily list out the approved comments.

            <%- @blog_post.approved_comments.each do |comment| -%>
              <%= comment.author %> said:
              <%= comment.content %>
            <%- end -%>
            

UPDATE: Shawn reminded me this week about named_scope, which was added in Rails 2.1. It makes custom associations a bit easier and more full-featured. You can get the same approved and non-approved comments with named_scope:

            class Comment < ActiveRecord::Base
              belongs_to :blog_post
              named_scope :approved, :conditions => ["approved = ?", true]
              named_scope :unapproved, :conditions => ["approved = ?", false]
            end
            

Notice that now the named_scope declarations go in the Comment model instead of the BlogPost model like the custom associations. You get the approved comments for a post with this line:

            <%= blog_post.comments.approved %>
            

You can also combine named_scope calls when selecting records. Suppose our Comment model now has a named_scope for both approved and unapproved comments, as well as comments made by anonymous authors.

            class Comment < ActiveRecord::Base
              belongs_to :post
              named_scope :approved, :conditions => ["approved = ?", true]
              named_scope :unapproved, :conditions => ["approved = ?", false]
              named_scope :anonymous, :conditions => ["name = ?", 'Anonymous']
            end
            

You can use this to find all of the approved comments for a post where the author is 'Anonymous'.

            <%= blog_post.comments.approved.anonymous %>
            

To add even more functionality to named_scope, you can add conditions to the call on the fly.

            <%= post.comments.approved.all(:conditions => ["created_at > ?", 2.weeks.ago]) %>
            

This will pass the additional date condition to the find, making it possible to refine your searches even more.

Render Partial with Collection/Object

This is how I've always done my partials.

The view (index.html.erb):

            <%- @posts.each do |post| -%>
              <%= render :partial => 'post', :locals => {:post => post} %>
            <%- end -%>
            

The partial (_post.html.erb):

            <%= post.title %> written by <%= post.author %>
            

I can simplify the call to the partial down to only one line of code (the partial itself will stay the same).

            <div id="all_posts">
              <%= render :partial => 'post', :collection => @posts %>
            </div>
            

By specifying the collection option, the view will call the partial post for each item in the @posts array.

But, let's say I wanted to call the partial for only one post. The old way:

            <div id="single_post">
              <%= render :partial => 'post', :locals => {:post => @post} %>
            </div>
            

Not terrible, but we can make it easier with the object option.

            <div id="single_post">
              <%= render :partial => 'post', :object => @post %>
            </div>
            

This will call the partial, and pass it only the object that we specify. Shorter and cleaner.

RJS with link_to_function

If you have several things on your page that need to be updated, and you want to do it with a javascript call instead of an AJAX call to the server, you can do it by passing a block to the link_to_function method.

Suppose this is my view:

            <div id="list">
              <p id="list_title"><%= @list.title %></p>
              <div id="list_items">
                <%= render :partial => 'item', :collection => @list.items %>
              </div>
              <%= link_to_function 'Change it up' do |page|
                page.replace_html 'list_items', 'New Item Title'
                page.hide 'list_items'
              end %>
            </div>
            

This is a poor example, but hopefully you can see what I'm trying to illustrate here.

Simplified FIND in Rails 2.1

With the release of Rails 2.1, they've added some much-needed find methods for easily getting all, first and last records for a model.

            @all_posts = Post.all
            @first_post = Post.first
            @last_post = Post.last
            

And, of course, you can pass conditions and order options to the new find methods.

            @all_posts = Post.all(:order => :updated_at)
            @first_post = Post.first(:conditions => ["title LIKE ?", '%Rails%'])
            @last_post = Post.last(:order => 'created_at DESC')
            

Tagged: tips, ruby, rails