rails find model class from controller

_search_form.html.erb

<%= form_tag(common_search_url,:class=>"navbar-search") do %>
  <%= text_field_tag(:q,params[:q] || I18n.t("menu.search"), :class => "search-query") %>
  <!--%- @model_class = params[:controller].capitalize.singularize if params[:controller].capitalize.singularize.class_exists? -%-->
  <%- @type_choose = params[:type] if (params.has_key? :type) and params[:type].present? -%>
  <%- @model_class = params[:controller].classify.constantize if params[:controller].classify.class_exists?  -%>
  <%- @model_class = params[:controller].gsub(/\w+([@\s\/]+)/,"").classify.constantize if params[:controller].gsub(/\w+([@\s\/]+)/,"").classify.class_exists?  -%>
  <% unless @model_class.nil? %>
    <%= hidden_field_tag 'model', @model_class.to_s %>
    <% if (@model_class.method_defined? :columns) or (@model_class.respond_to? :columns) %>
     <!--%= select_tag "type", options_from_collection_for_select(@model_class.columns, "name", "name")%-->
     <%= select_tag "type", options_for_select(model_columns_collection(@model_class),@type_choose)%>
    <% else %>
      <% if (@model_class.method_defined? :fields) or (@model_class.respond_to? :fields) %>
        <%= select_tag "type", options_for_select(model_columns_collection(@model_class),@type_choose) %>
        <!--%= select_tag "type", options_from_collection_for_select(@model_class.fields.to_a, "first", "first")%-->
      <% end %>
    <% end %>
  <% end %>
<% end %>

common_controller.rb

class CommonController < ApplicationController
  authorize_resource :class => false
  def search
    if (params.has_key? "model") and (params["model"].present?)
      @model_class = params[:model].constantize
      @results = @model_class.where params[:type] => params[:q]
      if @results.empty?
        @results = @model_class.where("#{params[:type].to_s}. like '%#{params[:q]}%'")
      end
    end
    render :template => 'common/search_result.html.erb'
  end
end

common_helper.rb

module CommonHelper
  def model_columns_collection(model_class = nil, whitelist = false )
    if (model_class.method_defined? :columns) or (model_class.respond_to? :columns)
      if whitelist
      #model_class.columns.collect{|column| [model_class.human_attribute_name(column.name),column.name]}
      #model_class.attribute_names.collect{|column| [model_class.human_attribute_name(column),column]}
        model_class.attr_accessible[:default].collect{|column| [model_class.human_attribute_name(column),column]}
      else
        model_class.column_names.collect{|column| [model_class.human_attribute_name(column),column]}
      end

    else
      if (model_class.method_defined? :fields) or (model_class.respond_to? :fields)
      model_class.fields.to_a.collect{|field| [model_class.human_attribute_name(field.first),field.first]}
      end
    end
  end
end

lib_core.rb

1.9.2p290 :026 > Object.const_defined? :Knowledge
 => true 
1.9.2p290 :027 > Rails.const_defined? :Knowledge
 => true 
 1.9.2p290 :030 > Rails.const_defined? :Recommend::RecommendTag
TypeError: :Recommend is not a class/module
1.9.2p290 :033 > Recommend::RecommendTag
 => Recommend::RecommendTag 
1.9.2p290 :034 > Recommend::RecommendTag.class
 => Class 
1.9.2p290 :039 > Object.const_defined? "User"
 => true
1.9.2p290 :045 > defined?( Recommend::RecommendTagasd)
 => nil 
1.9.2p290 :046 > defined?( Recommend::RecommendTag)
 => "constant" 
 
if defined?(MyClassName) == 'constant' && MyClassName.class == Class  
   puts "its a class" 
end

 class String
  def split_all(content = '')
    content = self if content.empty?
    content.split(/、|，|,|;|；|\ +|\||\r\n/) if content.class.eql? self.class
  end

  def to_class
      Kernel.const_get self
  rescue NameError 
      nil
  end

    class_name = self if class_name.nil?
    #defined? Knowledge => nil
    # "Knowledge".constantize
    # Knowledge(id: integer, title: string, summary: text, content: text, body: text, timeline_ids: text, knowledgebase_category_id: integer, created_by: integer, created_name: string, updated_by: integer, deleted_at: datetime, deleted_by: integer, delta: boolean, created_at: datetime, updated_at: datetime, thanks_count: integer, forwarding_count: integer, comments_count: integer, views_count: integer, source_info: string, auto_tags: text, face_file_name: string, face_content_type: string, face_file_size: string)
    #defined? Knowledge  => "constant"
    #eval("#{class_name}.is_a?(Class)") if eval("defined?(#{class_name})") == "constant"
    begin
      class_obj = class_name.classify.constantize
    rescue
      # failure handling goes here
      return false
    end
    class_obj.is_a?(Class)
  end

  def is_a_defined_class?
      true if self.to_class
  rescue NameError
      false
  end
end

 'String'.to_class
=> String
'unicorn'.to_class
=> nil
'puppy'.is_a_defined_class?
=> false
'Fixnum'.is_a_defined_class?
=> true

rails中处理复数单词的pluralize方法.rb

#在日常开发中，有时候会碰到要将一些单词按照它的数量来按单复数显示
 
#所幸rails已经考虑到了这一点，在ActionView中有一个方法
There are <%= pluralize @user.size, "user" %>.  

 pluralize(1, 'person') 
 # => 1
 person  pluralize(2, 'person') 
 # => 2 people  
 pluralize(3, 'person', 'users') 
 # => 3 users  
 pluralize(0, 'person') 
 # => 0 people 

"post".pluralize 
# => "posts" 
"octopus".pluralize 
# => "octopi"
"sheep".pluralize 
# => "sheep" 
"words".pluralize 
# => "words" 
"CamelOctopus".pluralize 
# => "CamelOctopi" 

1.9.2p290 :020 > "methods".singularize
 => "method" 
# http://zool.iteye.com/blog/900729

search_result.html.erb

<%- model_class = @model_class unless @model_class.nil? -%>

<div class="page-header">
  <h1><%=t 'common.search_result.title' %></h1>
</div>
<% unless model_class.nil?%>
  <div class = "results box">
    <table class="table table-condensed">
      <thead>
        <tr>
          <% model_columns_collection(@model_class,whitelist = true).each do |column|%>
            <th><%= model_class.human_attribute_name(column[1]) %></th>
          <% end %>
          <th><%=t '.actions', :default => t("helpers.actions") %></th>
        </tr>
      </thead>
      <tbody>
        <% if @results.present? %>
          <% @results.each do |result| %>
            <tr>
            <% model_columns_collection(@model_class,whitelist = true).each do |column|%>
              <td><%= result.read_attribute(column[1]) %></td>
            <% end %>
              <td>
                <% if self.respond_to? "auth_#{result.class.to_s.underscore.gsub("/","_")}_path" %>
                          <%= link_to t('.show', :default => t("helpers.links.show", :model => model_class.model_name.human)),
                             send("auth_#{result.class.to_s.underscore.gsub("/","_")}_path", result), :class => 'btn btn-mini' %>
                <%= link_to t('.edit', :default => t("helpers.links.edit", :model => model_class.model_name.human)),
                            send("edit_auth_#{result.class.to_s.underscore.gsub("/","_")}_path", result), :class => 'btn btn-mini' %>
                <!--%= link_to t('.destroy', :default => t("helpers.links.destroy", :model => model_class.model_name.human)),
                             send("auth_#{result.class.to_s.underscore.gsub("/","_")}_path", result)
                            :method => :delete,
                            :confirm => t('.confirm', :default => t("helpers.links.confirm", :default => 'Are you sure?')),
                            :class => 'btn btn-mini btn-danger' %-->
                <% else %>
                  <%= link_to t('.show', :default => t("helpers.links.show", :model => model_class.model_name.human)),
                               send("#{result.class.to_s.underscore.gsub("/","_")}_path", result), :class => 'btn btn-mini' %>
                  <%= link_to t('.edit', :default => t("helpers.links.edit", :model => model_class.model_name.human)),
                              send("edit_#{result.class.to_s.underscore.gsub("/","_")}_path", result), :class => 'btn btn-mini' %>
                  <!--%= link_to t('.destroy', :default => t("helpers.links.destroy", :model => model_class.model_name.human)),
                               send("#{result.class.to_s.underscore.gsub("/","_")}_path", result)
                              :method => :delete,
                              :confirm => t('.confirm', :default => t("helpers.links.confirm", :default => 'Are you sure?')),
                              :class => 'btn btn-mini btn-danger' %-->
                  <% end %>
              </td>
            </tr>
          <% end %>
        <% end %>
      </tbody>
    </table>

  </div>
<% end %>