Rails - Jul 2006 - Introspecting validates_presence_of

Hello people,

I''d like to detect whether an attribute of a model has
vaildates_presence_of applied to it so I can automatically apply a
mandatory (*) to the field...it doesn''t look easy...any ideas?

Cheers,

-- 
Dan Webb
http://www.danwebb.net

Dan Webb wrote the following on 27.07.2006 02:28 :
> Hello people,
>
> I''d like to detect whether an attribute of a model has
> vaildates_presence_of applied to it so I can automatically apply a
> mandatory (*) to the field...it doesn''t look easy...any ideas?
>
> Cheers,
>
My first reflex would be to override 
ActiveRecord::Base#validates_presence_of to populate a Hash in the model 
to keep track of which attribute is validated or not :

module ActiveRecord
    class Base
       alias_method :no_trancking_validates_presence_of, 
:validates_presence_of
       def validates_presence_of(*attr_names)
          @attr_presence_validated = Hash.new unless 
@attr_presence_validated
          attr_names.each {|a| @attr_presence_validated[a]=true}
          no_tracking_validates_presence_of(*attr_names)
       end
       def attr_presence_validated
          @attr_presence_validated
       end
    end
end

Put this in a lib and include it in environment.rb

Then in your view you can test with:
your_model.attr_presence_validated.include?(attr_name)

Lionel.

> Then in your view you can test with:
> your_model.attr_presence_validated.include?(attr_name)
>
> Lionel.
Yeah, I like it.  Nice and simple.  Thanks Lionel.

-- 
Dan Webb
http://www.danwebb.net

On Thursday 27 July 2006 02:28, Dan Webb wrote:
> I''d like to detect whether an attribute of a model has
> vaildates_presence_of applied to it so I can automatically apply a
> mandatory (*) to the field...it doesn''t look easy...any ideas?
Dan, below is some I''ve been using with a somewhat monkeypatched
version
of Rails pre-1.0. I''ve adapted it a bit so that it works with Rails 
1.1.4, but haven''t done any testing. All the code is under LGPL. When 
time permits, I hope to make this stuff into a plugin.

Michael


[Sorry for the mangled line breaks]

require ''active_record/reflection''

# Based on code by Sebastian Kanthak
# See http://dev.rubyonrails.org/ticket/861
module BoilerPlate
  module RailsExtensions # :nodoc:
    module ValidationReflection # :nodoc:
      VALIDATIONS = %w(
         validates_acceptance_of
         validates_associated
         validates_confirmation_of
         validates_exclusion_of
         validates_format_of
         validates_inclusion_of
         validates_length_of
         validates_numericality_of
         validates_presence_of
         validates_uniqueness_of
      ).freeze

      def self.included(base)
        base.extend(ClassMethods)

        for validation_type in VALIDATIONS
          base.module_eval <<-"end_eval"
            class << self
              
alias_method :#{validation_type}_without_reflection, :#{validation_type}

              def #{validation_type}_with_reflection(*attr_names)
                #{validation_type}_without_reflection(*attr_names)
                configuration = attr_names.last.is_a?(Hash) ? 
attr_names.pop : nil
                for attr_name in attr_names
                  write_inheritable_array "validations", [ 
ActiveRecord::Reflection::MacroReflection.new(:#{validation_type}, 
attr_name, configuration, self) ]
                end
              end

              
alias_method :#{validation_type}, :#{validation_type}_with_reflection
            end
          end_eval
        end
      end

      module ClassMethods

        # Returns an array of MacroReflection objects for all 
validations in the class
        def reflect_on_all_validations
          read_inheritable_attribute("validations") || []
        end

        # Returns an array of MacroReflection objects for all 
validations defined for the field +attr_name+ (expects a symbol)
        def reflect_on_validations_for(attr_name)
          reflect_on_all_validations.find_all do |reflection|
            reflection.name == attr_name
          end
        end

      end

    end
  end
end



require ''active_record/validations''

module BoilerPlate # :nodoc:
  module RailsExtensions # :nodoc:
    module Validations # :nodoc:
      def self.included(base)
        base.extend(ClassMethods)
      end

      module ClassMethods

        # Validates the presence of attributes and associations
        # where, according to database metadata, the corresponding
        # column must not be +null+.
        # Options:
        # <tt>:exclude</tt> - properties (as symbols) to be excluded
        def validates_presence_of_mandatory_content_columns(options = 
{})
          columns = mandatory_content_columns - Array(options[:exclude])
          validates_presence_of(*columns)
        end

        # Validates the lengths of string attributes against the
        # limit defined by their database type.
        # +Nil+ values are explicitly allowed as they are checked
        # with +validates_presence_of+
        # Options:
        # <tt>:exclude</tt> - attributes (as symbols) to be excluded
        def validates_lengths_of_string_attributes(options = {})
          columns = content_columns - Array(options[:exclude])
          columns.select { |col| col.type == :string and 
col.limit }.each do |col|
            validates_length_of(col.name.to_sym, :maximum => 
col.limit, :allow_nil => true)
          end
        end

        # Validates all associated objects.
        # +Nil+ values are explicitly allowed as they are checked
        # with +validates_presence_of+
        # Options:
        # <tt>:exclude</tt> - associations (as symbols) to be
excluded
        def validates_all_associated(options = {})
          associations = reflect_on_all_associations.map { |a| 
a.name } - Array(options[:exclude])
          validates_associated(*associations)
        end


        protected

        def mandatory_content_columns
          return @mandatory_content_columns if 
@mandatory_content_columns
          @mandatory_content_columns = []
          content_columns.find_all { |col| !col.null }.each do |col|
            @mandatory_content_columns << col.name
          end
          @mandatory_content_columns
        end

      end
    end
  end
end


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

module BoilerPlate # :nodoc:
  module RailsExtensions # :nodoc:

    module InstanceTagValidationsSupport
      def self.included(instance_tag)
        instance_tag.class_eval do
          alias_method :tag_without_validation, :tag
          alias_method :content_tag_without_validation, :content_tag
          alias_method :tag, :tag_with_validations
          alias_method :content_tag, :content_tag_with_validations
        end
      end

      def tag_with_validations(name, options = {})
        options = merge_validations!(options)
        tag_without_validation(name, options)
      end

      def content_tag_with_validations(name, content, options = {})
        options = merge_validations!(options)
        content_tag_without_validation(name, content, options)
      end


      private

      def merge_validations!(options)
        if options.delete(''ignore_validations'')
          return options
        end
        unless method_name && object.class.respond_to?
(:reflect_on_validations_for)
          return options
        end
        validations = 
object.class.reflect_on_validations_for(method_name.without_suffix(''_id'').to_sym)
        validations.each do |validation|
          case validation.macro
          when :validates_presence_of
            add_class_name!(options, ''mandatory'')
          when :validates_length_of
            if minlength = validation_minlength(validation.options)
              add_class_name!(options,
encode_validation(''minlength'',
minlength))
            end
            if maxlength = validation_maxlength(validation.options)
              add_class_name!(options,
encode_validation(''maxlength'',
maxlength))
            end
          when :validates_numericality_of
            add_class_name!(options, ''numeric'')
          when :validates_inclusion_of
            values = validation.options[:in]
            if values.kind_of?(Range)
### FIXME
              RAILS_DEFAULT_LOGGER.debug("Only inclusion validations for 
inclusive Ranges are supported") if values.exclude_end?
              add_class_name!(options,
encode_validation(''range'',
values.begin, values.end))
            else
### FIXME
              RAILS_DEFAULT_LOGGER.debug("Only inclusion validations for 
inclusive Ranges are supported")
            end
          when :validates_format_of
            add_class_name!(options,
              encode_validation(''format'',
validation.options[:with]))
          end
        end
        options
      end

      def add_class_name!(options, class_name)
        return options unless class_name
        options.stringify_keys! ### REMOVE when possible
        class_names = options[''class'']
        if class_names.blank?
          class_names = class_name
        else
          class_names += '' '' + class_name unless
class_names.include?
(class_name)
        end
        options[''class''] = class_names
        options
      end

      def encode_validation(name, *values)
        values = values.map {|v| 
CGI.escape(v.inspect).gsub(''+'',
''%20'')}.join(''_'')
        "validate_#{name}_#{values}"
      end

      def validation_minlength(options)
        minlength = options[:minimum]
        if minlength.nil?
          if range = options[:within]
            minlength = range.begin
          end
        end
        minlength
      end

      def validation_maxlength(options)
        maxlength = options[:maximum]
        if maxlength.nil?
          if range = options[:within]
            maxlength = range.exclude_end? ? range.end - 1 : range.end
          end
        end
        maxlength
      end

    end
  end
end



Then, say, in your environment.rb

ActiveRecord::Base.class_eval do
  include BoilerPlate::RailsExtensions::ValidationReflection
  include BoilerPlate::RailsExtensions::Validations
end

ActionView::Helpers::InstanceTag.class_eval do
  include BoilerPlate::RailsExtensions::InstanceTagValidationsSupport
end

-- 
Michael Schuerig
mailto:michael@schuerig.de
http://www.schuerig.de/michael/

Is this really enough? What if you have:

validates_length_of :foo, :minimum => 10

or any other number of validations that may not allow nil but can be used as
a more restrictive validator for presence of data.
-- 
View this message in context:
http://www.nabble.com/Introspecting-validates_presence_of-tf2008440.html#a5526552
Sent from the RubyOnRails Users forum at Nabble.com.

On Thursday 27 July 2006 19:56, Michael Schuerig wrote:
> I hope to make this stuff into a plugin.
And so I did. A first, rough version. What I don''t understand is how to
publish it, although I had a look at the RailsPluginPackageTask[*]. For 
the time being I just want to upload all that''s needed to my personal 
web site where I don''t have SVN support.

Michael

[*] 
http://www.mandhro.com/2006/07/03/publising-rails-plug-ins-with-rake/

-- 
Michael Schuerig
mailto:michael@schuerig.de
http://www.schuerig.de/michael/

I''d recommend using Google''s new SVN hosting
(http://code.google.com/
hosting/) and then posting it at http://www.agilewebdevelopment.com/ 
plugins/.

--
Benjamin Curtis
http://www.bencurtis.com/
http://www.tesly.com/ -- Collaborative test case management
http://www.agilewebdevelopment.com/ -- Resources for the Rails community



On Jul 27, 2006, at 4:49 PM, Michael Schuerig wrote:
> On Thursday 27 July 2006 19:56, Michael Schuerig wrote:
>> I hope to make this stuff into a plugin.
>
> And so I did. A first, rough version. What I don''t understand is  
> how to
> publish it, although I had a look at the RailsPluginPackageTask[*].  
> For
> the time being I just want to upload all that''s needed to my
personal
> web site where I don''t have SVN support.
>
> Michael
>
> [*]
> http://www.mandhro.com/2006/07/03/publising-rails-plug-ins-with-rake/
>
> -- 
> Michael Schuerig
> mailto:michael@schuerig.de
> http://www.schuerig.de/michael/
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
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On Friday 28 July 2006 18:00, Benjamin Curtis wrote:
> I''d recommend using Google''s new SVN hosting
(http://code.google.com/
> hosting/) and then posting it at http://www.agilewebdevelopment.com/
> plugins/.
Why Google over RubyForge?

Michael

-- 
Michael Schuerig
mailto:michael@schuerig.de
http://www.schuerig.de/michael/

Oh, no reason, I assumed since you were asking the question that  
either rubyforge or sourceforge weren''t appealing to you.

--
Benjamin Curtis
http://www.bencurtis.com/
http://www.tesly.com/ -- Collaborative test case management
http://www.agilewebdevelopment.com/ -- Resources for the Rails community



On Jul 28, 2006, at 9:21 AM, Michael Schuerig wrote:
> On Friday 28 July 2006 18:00, Benjamin Curtis wrote:
>> I''d recommend using Google''s new SVN hosting
(http://code.google.com/
>> hosting/) and then posting it at http://www.agilewebdevelopment.com/
>> plugins/.
>
> Why Google over RubyForge?
>
> Michael
>
> -- 
> Michael Schuerig
> mailto:michael@schuerig.de
> http://www.schuerig.de/michael/
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
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On Friday 28 July 2006 19:10, Benjamin Curtis wrote:
> Oh, no reason, I assumed since you were asking the question that
> either rubyforge or sourceforge weren''t appealing to you.
Ah, that''s been a misunderstanding, then. I just don''t want to
go to the
trouble of publishing a plugin on *any* of these sites right now. I''m 
just trying to put it on my own website. I''ve finally figured out what 
the index listings ought to look like after reading the source code of 
the plugin installer.

Michael

-- 
Michael Schuerig
mailto:michael@schuerig.de
http://www.schuerig.de/michael/