active_record_helper.rb

require 'cgi'
require 'action_view/helpers/form_helper'

module ActionView
  class Base
    @@field_error_proc = Proc.new{ |html_tag, instance| "<div class=\"fieldWithErrors\">#{html_tag}</div>" }
    cattr_accessor :field_error_proc
  end

  module Helpers
    # The Active Record Helper makes it easier to create forms for records kept in instance variables. The most far-reaching is the +form+
    # method that creates a complete form for all the basic content types of the record (not associations or aggregations, though). This
    # is a great way of making the record quickly available for editing, but likely to prove lackluster for a complicated real-world form.
    # In that case, it's better to use the +input+ method and the specialized +form+ methods in link:classes/ActionView/Helpers/FormHelper.html
    module ActiveRecordHelper
      # Returns a default input tag for the type of object returned by the method. For example, if <tt>@post</tt>
      # has an attribute +title+ mapped to a +VARCHAR+ column that holds "Hello World":
      #
      #   input("post", "title")
      #   # => <input id="post_title" name="post[title]" size="30" type="text" value="Hello World" />
      def input(record_name, method, options = {})
        InstanceTag.new(record_name, method, self).to_tag(options)
      end

      # Returns an entire form with all needed input tags for a specified Active Record object. For example, if <tt>@post</tt>
      # has attributes named +title+ of type +VARCHAR+ and +body+ of type +TEXT+ then
      #
      #   form("post") 
      #
      # would yield a form like the following (modulus formatting):
      #
      #   <form action='/posts/create' method='post'>
      #     <p>
      #       <label for="post_title">Title</label><br />
      #       <input id="post_title" name="post[title]" size="30" type="text" value="Hello World" />
      #     </p>
      #     <p>
      #       <label for="post_body">Body</label><br />
      #       <textarea cols="40" id="post_body" name="post[body]" rows="20"></textarea>
      #     </p>
      #     <input name="commit" type="submit" value="Create" />
      #   </form>
      #
      # It's possible to specialize the form builder by using a different action name and by supplying another
      # block renderer. For example, if <tt>@entry</tt> has an attribute +message+ of type +VARCHAR+ then
      #
      #   form("entry",
      #     :action => "sign",
      #     :input_block => Proc.new { |record, column|
      #       "#{column.human_name}: #{input(record, column.name)}<br />"
      #   })
      #
      # would yield a form like the following (modulus formatting):
      #
      #   <form action="/entries/sign" method="post">
      #     Message:
      #     <input id="entry_message" name="entry[message]" size="30" type="text" /><br />
      #     <input name="commit" type="submit" value="Sign" />
      #   </form>
      #
      # It's also possible to add additional content to the form by giving it a block, such as:
      #
      #   form("entry", :action => "sign") do |form|
      #     form << content_tag("b", "Department")
      #     form << collection_select("department", "id", @departments, "id", "name")
      #   end
      #
      # The following options are available:
      #
      # * <tt>:action</tt> - The action used when submitting the form (default: +create+ if a new record, otherwise +update+).
      # * <tt>:input_block</tt> - Specialize the output using a different block, see above.
      # * <tt>:method</tt> - The method used when submitting the form (default: +post+).
      # * <tt>:multipart</tt> - Whether to change the enctype of the form to "multipart/form-data", used when uploading a file (default: +false+).
      # * <tt>:submit_value</tt> - The text of the submit button (default: "Create" if a new record, otherwise "Update").
      def form(record_name, options = {})
        record = instance_variable_get("@#{record_name}")

        options = options.symbolize_keys
        options[:action] ||= record.new_record? ? "create" : "update"
        action = url_for(:action => options[:action], :id => record)

        submit_value = options[:submit_value] || options[:action].gsub(/[^\w]/, '').capitalize

        contents = form_tag({:action => action}, :method =>(options[:method] || 'post'), :enctype => options[:multipart] ? 'multipart/form-data': nil)
        contents << hidden_field(record_name, :id) unless record.new_record?
        contents << all_input_tags(record, record_name, options)
        yield contents if block_given?
        contents << submit_tag(submit_value)
        contents << '</form>'
      end

      # Returns a string containing the error message attached to the +method+ on the +object+ if one exists.
      # This error message is wrapped in a <tt>DIV</tt> tag, which can be extended to include a +prepend_text+ and/or +append_text+
      # (to properly explain the error), and a +css_class+ to style it accordingly. +object+ should either be the name of an instance variable or
      # the actual object. As an example, let's say you have a model <tt>@post</tt> that has an error message on the +title+ attribute:
      #
      #   <%= error_message_on "post", "title" %>
      #   # => <div class="formError">can't be empty</div>
      #
      #   <%= error_message_on @post, "title" %>
      #   # => <div class="formError">can't be empty</div>
      #
      #   <%= error_message_on "post", "title", "Title simply ", " (or it won't work).", "inputError" %>
      #   # => <div class="inputError">Title simply can't be empty (or it won't work).</div>
      def error_message_on(object, method, prepend_text = "", append_text = "", css_class = "formError")
        if (obj = (object.respond_to?(:errors) ? object : instance_variable_get("@#{object}"))) &&
          (errors = obj.errors.on(method))
          content_tag("div", "#{prepend_text}#{errors.is_a?(Array) ? errors.first : errors}#{append_text}", :class => css_class)
        else 
          ''
        end
      end

      # Returns a string with a <tt>DIV</tt> containing all of the error messages for the objects located as instance variables by the names
      # given.  If more than one object is specified, the errors for the objects are displayed in the order that the object names are
      # provided.
      #
      # This <tt>DIV</tt> can be tailored by the following options:
      #
      # * <tt>:header_tag</tt> - Used for the header of the error div (default: "h2").
      # * <tt>:id</tt> - The id of the error div (default: "errorExplanation").
      # * <tt>:class</tt> - The class of the error div (default: "errorExplanation").
      # * <tt>:object</tt> - The object (or array of objects) for which to display errors,
      #   if you need to escape the instance variable convention.
      # * <tt>:object_name</tt> - The object name to use in the header, or any text that you prefer.
      #   If <tt>:object_name</tt> is not set, the name of the first object will be used.
      # * <tt>:header_message</tt> - The message in the header of the error div.  Pass +nil+
      #   or an empty string to avoid the header message altogether. (Default: "X errors
      #   prohibited this object from being saved").
      # * <tt>:message</tt> - The explanation message after the header message and before
      #   the error list.  Pass +nil+ or an empty string to avoid the explanation message
      #   altogether. (Default: "There were problems with the following fields:").
      #
      # To specify the display for one object, you simply provide its name as a parameter.
      # For example, for the <tt>@user</tt> model:
      # 
      #   error_messages_for 'user'
      #
      # To specify more than one object, you simply list them; optionally, you can add an extra <tt>:object_name</tt> parameter, which
      # will be the name used in the header message:
      #
      #   error_messages_for 'user_common', 'user', :object_name => 'user'
      #
      # If the objects cannot be located as instance variables, you can add an extra <tt>:object</tt> paremeter which gives the actual
      # object (or array of objects to use):
      #
      #   error_messages_for 'user', :object => @question.user
      #
      # NOTE: This is a pre-packaged presentation of the errors with embedded strings and a certain HTML structure. If what
      # you need is significantly different from the default presentation, it makes plenty of sense to access the <tt>object.errors</tt>
      # instance yourself and set it up. View the source of this method to see how easy it is.
      def error_messages_for(*params)
        options = params.extract_options!.symbolize_keys
        if object = options.delete(:object)
          objects = [object].flatten
        else
          objects = params.collect {|object_name| instance_variable_get("@#{object_name}") }.compact
        end
        count   = objects.inject(0) {|sum, object| sum + object.errors.count }
        unless count.zero?
          html = {}
          [:id, :class].each do |key|
            if options.include?(key)
              value = options[key]
              html[key] = value unless value.blank?
            else
              html[key] = 'errorExplanation'
            end
          end
          options[:object_name] ||= params.first
          options[:header_message] = "#{pluralize(count, 'error')} prohibited this #{options[:object_name].to_s.gsub('_', ' ')} from being saved" unless options.include?(:header_message)
          options[:message] ||= 'There were problems with the following fields:' unless options.include?(:message)
          error_messages = objects.sum {|object| object.errors.full_messages.map {|msg| content_tag(:li, msg) } }.join

          contents = ''
          contents << content_tag(options[:header_tag] || :h2, options[:header_message]) unless options[:header_message].blank?
          contents << content_tag(:p, options[:message]) unless options[:message].blank?
          contents << content_tag(:ul, error_messages)

          content_tag(:div, contents, html)
        else
          ''
        end
      end

      private
        def all_input_tags(record, record_name, options)
          input_block = options[:input_block] || default_input_block
          record.class.content_columns.collect{ |column| input_block.call(record_name, column) }.join("\n")
        end

        def default_input_block
          Proc.new { |record, column| %(<p><label for="#{record}_#{column.name}">#{column.human_name}</label><br />#{input(record, column.name)}</p>) }
        end
    end

    class InstanceTag #:nodoc:
      def to_tag(options = {})
        case column_type
          when :string
            field_type = @method_name.include?("password") ? "password" : "text"
            to_input_field_tag(field_type, options)
          when :text
            to_text_area_tag(options)
          when :integer, :float, :decimal
            to_input_field_tag("text", options)
          when :date
            to_date_select_tag(options)
          when :datetime, :timestamp
            to_datetime_select_tag(options)
          when :time
            to_time_select_tag(options)
          when :boolean
            to_boolean_select_tag(options)
        end
      end

      alias_method :tag_without_error_wrapping, :tag
      def tag(name, options)
        if object.respond_to?("errors") && object.errors.respond_to?("on")
          error_wrapping(tag_without_error_wrapping(name, options), object.errors.on(@method_name))
        else
          tag_without_error_wrapping(name, options)
        end
      end

      alias_method :content_tag_without_error_wrapping, :content_tag
      def content_tag(name, value, options)
        if object.respond_to?("errors") && object.errors.respond_to?("on")
          error_wrapping(content_tag_without_error_wrapping(name, value, options), object.errors.on(@method_name))
        else
          content_tag_without_error_wrapping(name, value, options)
        end
      end

      alias_method :to_date_select_tag_without_error_wrapping, :to_date_select_tag
      def to_date_select_tag(options = {}, html_options = {})
        if object.respond_to?("errors") && object.errors.respond_to?("on")
          error_wrapping(to_date_select_tag_without_error_wrapping(options, html_options), object.errors.on(@method_name))
        else
          to_date_select_tag_without_error_wrapping(options, html_options)
        end
      end

      alias_method :to_datetime_select_tag_without_error_wrapping, :to_datetime_select_tag
      def to_datetime_select_tag(options = {}, html_options = {})
        if object.respond_to?("errors") && object.errors.respond_to?("on")
            error_wrapping(to_datetime_select_tag_without_error_wrapping(options, html_options), object.errors.on(@method_name))
          else
            to_datetime_select_tag_without_error_wrapping(options, html_options)
        end
      end

      alias_method :to_time_select_tag_without_error_wrapping, :to_time_select_tag
      def to_time_select_tag(options = {}, html_options = {})
        if object.respond_to?("errors") && object.errors.respond_to?("on")
          error_wrapping(to_time_select_tag_without_error_wrapping(options, html_options), object.errors.on(@method_name))
        else
          to_time_select_tag_without_error_wrapping(options, html_options)
        end
      end

      def error_wrapping(html_tag, has_error)
        has_error ? Base.field_error_proc.call(html_tag, self) : html_tag
      end

      def error_message
        object.errors.on(@method_name)
      end

      def column_type
        object.send("column_for_attribute", @method_name).type
      end
    end
  end
end