Enough with concepts, ideas and diagrams: it’s time to start coding something. Everyone knows what’s the first step when creating a Rails applications, but anyhow, here it is:
1rails italysimplyThen I create a new development database, load it up with the schema I previously prepared and modify the config/database.yml to be able to connect to it. Nothing new here.
I actually had to modify the schema a little bit:
- I changed all the names for the foreign keys to something more evocative than “has_many” or “has_one”
- I added a level column to the states, availabilities and conditions table
- I removed the description column from the categories table
Great, but… hang on: now some of the database tables look awfully similar with each other:
- statuses
- states
- roles
- types
- tags
- conditions
- availabilities
- categories
They all have a name column, some of them have a name column as well, they’ll hold only a relative small number of records which will hardly ever be deleted. In fact, I was tempted to use Enums for some of those things…
Anyhow, I’ll still have to add and modify data in those tables, so it looks like I kinda need to create 8 controllers, 8 models and about four views for each one of them. No way. Fair enough for the controllers and models, but I’m not going to create 32 views which all look exactly the same. Rails should be smarter than that!And it is, luckily. Derek Sivers & C. came out with an interesting Shared Controller concept, which could be just what I’m looking for in this case. Actually I need something really simple in this case:
- Put all the CRUD logic into one controller
- Create only one set of views
Here’s the controller:
app/controllers/admin/lite_controller.rb
1class Admin::LiteController < ApplicationController 2 3 layout 'admin' 4 5 before_filter :prepare 6 7 def prepare 8 @item_name = model.to_s 9 end 10 11 def index 12 list 13 end 14 15 verify :method => :post, :only => [ :destroy, :create, :update ], 16 :redirect_to => { :action => :list } 17 18 def list 19 ordering = model.column_names.include?('level') ? 'level ASC' : 'name ASC' 20 @items = model.find(:all, :order => ordering) 21 render('lite/list') 22 end 23 24 def show 25 @item = model.find(params[:id]) 26 render('lite/show') 27 end 28 29 def new 30 @item = model.new 31 render('lite/new') 32 end 33 34 def create 35 @item = model.new(params[:"#{@item_name.downcase}"]) 36 if @item.save 37 flash[:notice] = @item_name+' was successfully created.' 38 redirect_to :action => 'list' 39 else 40 render('lite/new') 41 end 42 end 43 44 def edit 45 @item = model.find(params[:id]) 46 render('lite/edit') 47 end 48 49 def update 50 @item = model.find(params[:id]) 51 if @item.update_attributes(params[:"#{@item_name.downcase}"]) 52 flash[:notice] = @item_name+' was successfully updated.' 53 redirect_to :action => 'list' 54 else 55 render('lite/edit') 56 end 57 end 58end
1class Admin::LiteController < ApplicationController
2
3 layout ‘admin’
4
5 before_filter :prepare
6
7 def prepare
8item_name</span> = model.to_s <span class="line-numbers"> <a href="#n9" name="n9">9</a></span> <span class="keyword">end</span> <span class="line-numbers"><strong><a href="#n10" name="n10">10</a></strong></span> <span class="line-numbers"><a href="#n11" name="n11">11</a></span> <span class="keyword">def</span> <span class="function">index</span> <span class="line-numbers"><a href="#n12" name="n12">12</a></span> list <span class="line-numbers"><a href="#n13" name="n13">13</a></span> <span class="keyword">end</span> <span class="line-numbers"><a href="#n14" name="n14">14</a></span> <span class="line-numbers"><a href="#n15" name="n15">15</a></span> verify <span class="symbol">:method</span> => <span class="symbol">:post</span>, <span class="symbol">:only</span> => [ <span class="symbol">:destroy</span>, <span class="symbol">:create</span>, <span class="symbol">:update</span> ], <span class="line-numbers"><a href="#n16" name="n16">16</a></span> <span class="symbol">:redirect_to</span> => { <span class="symbol">:action</span> => <span class="symbol">:list</span> } <span class="line-numbers"><a href="#n17" name="n17">17</a></span> <span class="line-numbers"><a href="#n18" name="n18">18</a></span> <span class="keyword">def</span> <span class="function">list</span> <span class="line-numbers"><a href="#n19" name="n19">19</a></span> ordering = model.column_names.include?(<span class="string"><span class="delimiter">'</span><span class="content">level</span><span class="delimiter">'</span></span>) ? <span class="string"><span class="delimiter">'</span><span class="content">level ASC</span><span class="delimiter">'</span></span> : <span class="string"><span class="delimiter">'</span><span class="content">name ASC</span><span class="delimiter">'</span></span> <span class="line-numbers"><strong><a href="#n20" name="n20">20</a></strong></span> <span class="instance-variable">items = model.find(:all, :order => ordering)
21 render(‘lite/list’)
22 end
23
24 def show
25item</span> = model.find(params[<span class="symbol">:id</span>]) <span class="line-numbers"><a href="#n26" name="n26">26</a></span> render(<span class="string"><span class="delimiter">'</span><span class="content">lite/show</span><span class="delimiter">'</span></span>) <span class="line-numbers"><a href="#n27" name="n27">27</a></span> <span class="keyword">end</span> <span class="line-numbers"><a href="#n28" name="n28">28</a></span> <span class="line-numbers"><a href="#n29" name="n29">29</a></span> <span class="keyword">def</span> <span class="function">new</span> <span class="line-numbers"><strong><a href="#n30" name="n30">30</a></strong></span> <span class="instance-variable">item = model.new
31 render(‘lite/new’)
32 end
33
34 def create
35item</span> = model.new(params[<span class="symbol"><span class="symbol">:</span><span class="delimiter">"</span><span class="inline"><span class="inline-delimiter">#{</span><span class="instance-variable">item_name.downcase}"])
36 ifitem</span>.save <span class="line-numbers"><a href="#n37" name="n37">37</a></span> flash[<span class="symbol">:notice</span>] = <span class="instance-variable">item_name‘ was successfully created.’
38 redirect_to :action => ‘list’
39 else
40 render(‘lite/new’)
41 end
42 end
43
44 def edit
45item</span> = model.find(params[<span class="symbol">:id</span>]) <span class="line-numbers"><a href="#n46" name="n46">46</a></span> render(<span class="string"><span class="delimiter">'</span><span class="content">lite/edit</span><span class="delimiter">'</span></span>) <span class="line-numbers"><a href="#n47" name="n47">47</a></span> <span class="keyword">end</span> <span class="line-numbers"><a href="#n48" name="n48">48</a></span> <span class="line-numbers"><a href="#n49" name="n49">49</a></span> <span class="keyword">def</span> <span class="function">update</span> <span class="line-numbers"><strong><a href="#n50" name="n50">50</a></strong></span> <span class="instance-variable">item = model.find(params[:id])
51 ifitem</span>.update_attributes(params[<span class="symbol"><span class="symbol">:</span><span class="delimiter">"</span><span class="inline"><span class="inline-delimiter">#{</span><span class="instance-variable">item_name.downcase}"])
52 flash[:notice] = @item_name‘ was successfully updated.’
53 redirect_to :action => ‘list’
54 else
55 render(‘lite/edit’)
56 end
57 end
58end
Then all I need to do is create eight controllers with just a few lines of code in each:
app/controllers/admin/statuses_controller.rb
1class Admin::StatusesController < Admin::LiteController 2 def model 3 Status 4 end 5end
Basically, I just need to specify which model the specific controller takes care of, Ruby’s inheritance does the rest. The model name will be passed to the views like this:
app/controllers/admin/lite_controller.rb
1def prepare 2 @item_name = model.to_s 3end
And each method uses the model method to access the model, like this:
app/controllers/admin/lite_controller.rb
1def create 2 @item = model.new(params[:"#{@item_name.downcase}"]) 3 if @item.save 4 flash[:notice] = @item_name+' was successfully created.' 5 redirect_to :action => 'list' 6 else 7 render('lite/new') 8 end 9end
1def create
2item</span> = model.new(params[<span class="symbol"><span class="symbol">:</span><span class="delimiter">"</span><span class="inline"><span class="inline-delimiter">#{</span><span class="instance-variable">item_name.downcase}"])
3 ifitem</span>.save <span class="line-numbers"> <a href="#n4" name="n4">4</a></span> flash[<span class="symbol">:notice</span>] = <span class="instance-variable">item_name+‘ was successfully created.’
5 redirect_to :action => ‘list’
6 else
7 render(‘lite/new’)
8 end
9end
Note how the params are collected:
1@item = model.new(params[:"#{@item_name.downcase}"])
params[:"#{item_name.downcase}"]@ at runtime becomes params[:status] or params[:role] etc. etc., depending on which controller is called. Sweet.
The views? Modified accordingly:
app/views/lite/edit.rb
1<h1>Editing <%= @item_name %></h1> 2 3<% form_tag :action => 'update', :id => @item do %> 4 <%= render :partial => 'lite/form' %> 5 <%= submit_tag 'Edit' %> 6<% end %> 7 8<%= link_to 'Show', :action => 'show', :id => @item %> | 9<%= link_to 'Back', :action => 'list' %>
1<h1>Editing <%=item_name %></h1></span></span> <span class="line-numbers"> <a href="#n2" name="n2">2</a></span><span class="string"><span class="content"></span></span> <span class="line-numbers"> <a href="#n3" name="n3">3</a></span><span class="string"><span class="content"><% form_tag :action </span><span class="delimiter">=</span></span>> <span class="string"><span class="delimiter">'</span><span class="content">update</span><span class="delimiter">'</span></span>, <span class="symbol">:id</span> => <span class="instance-variable">item do %>
4 <%= render :partial => ‘lite/form’ >
5 <= submit_tag ‘Edit’ >
6< end >
7
8<= link_to ‘Show’, :action => ‘show’, :id => @item > |
9<= link_to ‘Back’, :action => ‘list’ %>
app/views/lite/_form.rb
1<%= error_messages_for 'item' %> 2<!--[form:lite]--> 3<p><label for="<%= @item_name.downcase %>_name">Name: </label> 4<%= text_field @item_name.downcase, 'name', {:value => @item.name} %></p> 5<% if @item.methods.include?('level') then %> 6 <p><label for="<%= @item_name.downcase %>_level">Level: </label> 7 <%= text_field @item_name.downcase, 'level', {:value => @item.level} %></p> 8<% end %> 9<!--[eoform:lite]-->
1<%= error_messages_for ‘item’ >
2<!—[form:lite]—>
3<p><label for="<=item_name.downcase %>_name</span><span class="delimiter">"</span></span>><span class="constant">Name</span>: <<span class="regexp"><span class="delimiter">/</span><span class="content">label></span></span> <span class="line-numbers"> <a href="#n4" name="n4">4</a></span><span class="regexp"><span class="content"><%= text_field @item_name.downcase, 'name', {:value => @item.name} %><</span><span class="delimiter">/</span></span>p> <span class="line-numbers"> <a href="#n5" name="n5">5</a></span><<span class="string"><span class="delimiter">% </span><span class="content">if</span><span class="delimiter"> </span></span><span class="instance-variable">item.methods.include?(‘level’) then %>
6 <p><label for="<%= @item_name.downcase >_level">Level: </label>
7 <= text_field @item_name.downcase, ‘level’, {:value => @item.level} ></p>
8< end %>
9<!—[eoform:lite]—>
Legacy Comments
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@Aleksandr:
Good question!
The answer is that being it my first project in Rails, I was still a bit unsure about REST.
On a side note, I’m currently considering using ActiveScaffold for things like this now… Will blog about it soon-ish.
Why aren’t you using REST?