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igotimac-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org

2006-Nov-06 15:08 UTC

Yet Another request to help DRY some code

The essential element I''m missing (I think), is some sort of hook to
help me iterate through all of my model''s to_one relationships.

My model has lots of them, but for a given object only 1 matters.  So
"att_value" is supposed to represent whichever one it is that matters.
(and the one that matters is determined by another attribute called
class_name)


class PageAttribute < ActiveRecord::Base

  belongs_to :page

  has_one :boolean_page_attribute, :class_name =>
''BooleanPageAttribute'', :dependent => :destroy
  has_one :date_page_attribute, :class_name =>
''DatePageAttribute'',
:dependent => :destroy
  has_one :string_page_attribute, :class_name =>
''StringPageAttribute'',
:dependent => :destroy
  has_one :page_link_page_attribute, :class_name =>
''PageLinkPageAttribute'', :dependent => :destroy
  has_one :uploaded_file_page_attribute, :class_name =>
''UploadedFilePageAttribute'', :dependent => :destroy

  def att_value
    if(self.class_name.to_s == ''BooleanPageAttribute'')
      return self.boolean_page_attribute
    end
    if(self.class_name.to_s == ''DatePageAttribute'')
      return self.date_page_attribute
    end
    if(self.class_name.to_s == ''StringPageAttribute'')
      logger.debug "returning string_page_attribute" +
string_page_attribute.to_s
      return self.string_page_attribute
    end
    if(self.class_name.to_s == ''PageLinkPageAttribute'')
      return self.page_link_page_attribute
    end
    if(self.class_name.to_s == ''UploadedFilePageAttribute'')
      return self.uploaded_file_page_attribute
    end
  end

  def att_value=(val)
    if(self.class_name.to_s == ''BooleanPageAttribute'')
      if val.is_a? Hash
        self.boolean_page_attribute.attributes = val
      else
        self.boolean_page_attribute = val
      end
    end
    if(self.class_name.to_s == ''DatePageAttribute'')
      if val.is_a? Hash
        self.date_page_attribute.attributes = val
      else
        self.date_page_attribute = val
      end
    end
    if(self.class_name.to_s == ''StringPageAttribute'')
      if val.is_a? Hash
        self.string_page_attribute.attributes = val
      else
        self.string_page_attribute = val
      end
    end
    if(self.class_name.to_s == ''PageLinkPageAttribute'')
      if val.is_a? Hash
        self.page_link_page_attribute.attributes = val
      else
        self.page_link_page_attribute = val
      end
    end
    if(self.class_name.to_s == ''UploadedFilePageAttribute'')
      if val.is_a? Hash
        self.uploaded_file_page_attribute.attributes = val
      else
        self.uploaded_file_page_attribute = val
      end
    end
  end

...etc...

end

thanks,
Jacob


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igotimac-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org

2006-Nov-07 15:26 UTC

head link

Yet Another request to help DRY some code

Basically, I''m looking for a hook that will let me iterate through all
my has_one relationships.

The idea of this class is that each PageAttribute should have exactly
one XX_page_attribute.  There are several possibilities for this, so
it''s supposed to be encapsulated by the att_value attribute. (and
attribute that returns and sets the proper XX_page_attribute) the
decision about which XX_page_attribute is based on another column of
PageAttribute: class_name.

any ideas?
thanks,
Jacob




class PageAttribute < ActiveRecord::Base

  belongs_to :page

  has_one :boolean_page_attribute, :class_name =>
''BooleanPageAttribute'', :dependent => :destroy
  has_one :date_page_attribute, :class_name =>
''DatePageAttribute'',
:dependent => :destroy
  has_one :string_page_attribute, :class_name =>
''StringPageAttribute'',
:dependent => :destroy
  has_one :page_link_page_attribute, :class_name =>
''PageLinkPageAttribute'', :dependent => :destroy
  has_one :uploaded_file_page_attribute, :class_name =>
''UploadedFilePageAttribute'', :dependent => :destroy

  def att_value
    if(self.class_name.to_s == ''BooleanPageAttribute'')
      return self.boolean_page_attribute
    end
    if(self.class_name.to_s == ''DatePageAttribute'')
      return self.date_page_attribute
    end
    if(self.class_name.to_s == ''StringPageAttribute'')
      logger.debug "returning string_page_attribute" +
string_page_attribute.to_s
      return self.string_page_attribute
    end
    if(self.class_name.to_s == ''PageLinkPageAttribute'')
      return self.page_link_page_attribute
    end
    if(self.class_name.to_s == ''UploadedFilePageAttribute'')
      return self.uploaded_file_page_attribute
    end
  end

  def att_value=(val)
    logger.debug("setting att_value from: " + val.to_s);

    if(self.class_name.to_s == ''BooleanPageAttribute'')
      if val.is_a? Hash
        self.boolean_page_attribute = BooleanPageAttribute.new(val)
      else
        self.boolean_page_attribute = val
      end
    end
    if(self.class_name.to_s == ''DatePageAttribute'')
      if val.is_a? Hash
        self.date_page_attribute = DatePageAttribute.new(val)
      else
        self.date_page_attribute = val
      end
    end
    if(self.class_name.to_s == ''StringPageAttribute'')
      if val.is_a? Hash
        self.string_page_attribute = StringPageAttribute.new(val)
      else
        self.string_page_attribute = val
      end
    end
    if(self.class_name.to_s == ''PageLinkPageAttribute'')
      if val.is_a? Hash
        self.page_link_page_attribute = PageLinkPageAttribute.new(val)
      else
        self.page_link_page_attribute = val
      end
    end
    if(self.class_name.to_s == ''UploadedFilePageAttribute'')
      if val.is_a? Hash
        self.uploaded_file_page_attribute UploadedFilePageAttribute.new(val)
      else
        self.uploaded_file_page_attribute = val
      end
    end
  end


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Jacob Burkhart

2006-Nov-07 18:32 UTC

head link

Yet Another request to help DRY some code

Basically, I''m looking for a hook that will let me iterate through all 
my has_one relationships.

The idea of this class is that each PageAttribute should have exactly 
one XX_page_attribute.  There are several possibilities for this, so 
it''s supposed to be encapsulated by the att_value attribute. (and 
attribute that returns and sets the proper XX_page_attribute) the 
decision about which XX_page_attribute is based on another column of 
PageAttribute: class_name.

any ideas?
thanks,
Jacob




class PageAttribute < ActiveRecord::Base

  belongs_to :page

  has_one :boolean_page_attribute, :class_name => 
''BooleanPageAttribute'', :dependent => :destroy
  has_one :date_page_attribute, :class_name =>
''DatePageAttribute'',
:dependent => :destroy
  has_one :string_page_attribute, :class_name =>
''StringPageAttribute'',
:dependent => :destroy
  has_one :page_link_page_attribute, :class_name => 
''PageLinkPageAttribute'', :dependent => :destroy
  has_one :uploaded_file_page_attribute, :class_name => 
''UploadedFilePageAttribute'', :dependent => :destroy

  def att_value
    if(self.class_name.to_s == ''BooleanPageAttribute'')
      return self.boolean_page_attribute
    end
    if(self.class_name.to_s == ''DatePageAttribute'')
      return self.date_page_attribute
    end
    if(self.class_name.to_s == ''StringPageAttribute'')
      logger.debug "returning string_page_attribute" + 
string_page_attribute.to_s
      return self.string_page_attribute
    end
    if(self.class_name.to_s == ''PageLinkPageAttribute'')
      return self.page_link_page_attribute
    end
    if(self.class_name.to_s == ''UploadedFilePageAttribute'')
      return self.uploaded_file_page_attribute
    end
  end

  def att_value=(val)
    logger.debug("setting att_value from: " + val.to_s);

    if(self.class_name.to_s == ''BooleanPageAttribute'')
      if val.is_a? Hash
        self.boolean_page_attribute = BooleanPageAttribute.new(val)
      else
        self.boolean_page_attribute = val
      end
    end
    if(self.class_name.to_s == ''DatePageAttribute'')
      if val.is_a? Hash
        self.date_page_attribute = DatePageAttribute.new(val)
      else
        self.date_page_attribute = val
      end
    end
    if(self.class_name.to_s == ''StringPageAttribute'')
      if val.is_a? Hash
        self.string_page_attribute = StringPageAttribute.new(val)
      else
        self.string_page_attribute = val
      end
    end
    if(self.class_name.to_s == ''PageLinkPageAttribute'')
      if val.is_a? Hash
        self.page_link_page_attribute = PageLinkPageAttribute.new(val)
      else
        self.page_link_page_attribute = val
      end
    end
    if(self.class_name.to_s == ''UploadedFilePageAttribute'')
      if val.is_a? Hash
        self.uploaded_file_page_attribute = 
UploadedFilePageAttribute.new(val)
      else
        self.uploaded_file_page_attribute = val
      end
    end
  end

-- 
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Rob Biedenharn

2006-Nov-07 19:19 UTC

head link

Re: Yet Another request to help DRY some code

On Nov 7, 2006, at 1:32 PM, Jacob Burkhart wrote:
>
> Basically, I''m looking for a hook that will let me iterate through
all
> my has_one relationships.
>
> The idea of this class is that each PageAttribute should have exactly
> one XX_page_attribute.  There are several possibilities for this, so
> it''s supposed to be encapsulated by the att_value attribute. (and
> attribute that returns and sets the proper XX_page_attribute) the
> decision about which XX_page_attribute is based on another column of
> PageAttribute: class_name.
>
> any ideas?
> thanks,
> Jacob
Check out ActiveRecord::Reflection#reflect_on_association(:has_one)

http://api.rubyonrails.org/classes/ActiveRecord/Reflection/ 
ClassMethods.html#M000592

But I wonder if you might not want STI for all the XxxPageAttributes  
if there should only be one of them.

-Rob

Rob Biedenharn		http://agileconsultingllc.com
Rob-xa9cJyRlE0mWcWVYNo9pwxS2lgjeYSpx@public.gmane.org




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igotimac-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org

2006-Nov-07 20:17 UTC

head link

Re: Yet Another request to help DRY some code

What''s STI?  I''d love if I could make DatePageAttribute and
StringPageAttribute simply subclasses of PageAttribute (but use the
table structure I have already).  Is this possible?  To make a Model
who is backed by a pair of tables?


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Wes Rogers

2006-Nov-07 20:25 UTC

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Re: Yet Another request to help DRY some code

STI means Single Table Inheritance.

You may want to look into Polymorphic Associations for this particular 
case. I recently encountered a similar problem in where using STI was 
just too ugly. Polymorphic Associations allow me to subclass out a 
"Content" model to a "Page" model and "Article",
etc.

http://wiki.rubyonrails.org/rails/pages/PolymorphicAssociations

Jacob Burkhart wrote:> What''s STI?  I''d love if I could make DatePageAttribute
and
> StringPageAttribute simply subclasses of PageAttribute (but use the
> table structure I have already).  Is this possible?  To make a Model
> who is backed by a pair of tables?

-- 
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Rob Biedenharn

2006-Nov-20 14:08 UTC

head link

Re: Yet Another request to help DRY some code

On Nov 7, 2006, at 10:26 AM, igotimac-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
wrote:
> Basically, I''m looking for a hook that will let me iterate through
all
> my has_one relationships.
http://rdoc.caboo.se/doc/classes/ActiveRecord/Reflection/ 
ClassMethods.html

In particular, you probably want to look at  
reflect_on_all_associations(:has_one)
> The idea of this class is that each PageAttribute should have exactly
> one XX_page_attribute.  There are several possibilities for this, so
> it''s supposed to be encapsulated by the att_value attribute. (and
> attribute that returns and sets the proper XX_page_attribute) the
> decision about which XX_page_attribute is based on another column of
> PageAttribute: class_name.
>
> any ideas?
> thanks,
> Jacob
Hope that helps.

-Rob

Rob Biedenharn		http://agileconsultingllc.com
Rob-xa9cJyRlE0mWcWVYNo9pwxS2lgjeYSpx@public.gmane.org




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Matt Jones

2006-Nov-20 14:54 UTC

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Re: Yet Another request to help DRY some code

On 11/7/06, igotimac-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
<igotimac-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:>
>
> Basically, I''m looking for a hook that will let me iterate through
all
> my has_one relationships.
>
> The idea of this class is that each PageAttribute should have exactly
> one XX_page_attribute.  There are several possibilities for this, so
> it''s supposed to be encapsulated by the att_value attribute. (and
> attribute that returns and sets the proper XX_page_attribute) the
> decision about which XX_page_attribute is based on another column of
> PageAttribute: class_name.
>
>This sounds like a classic use case for STI - have you considered using
that?
Essentially, all the various models (BooleanPageAttribute, etc.) would look
like
this:

class BooleanPageAttribute < PageAttribute
# any extra stuff
end

And PageAttribute would be:

class PageAttribute < ActiveRecord::Base
  belongs_to :page
  inheritance_column :class_name
end

(If you name your type indicator "type", then you don''t need
the
inheritance_column statement)

The schema for the page_attributes table would contain all of the data from
the various types.
The att_value methods above would be replaced with the normal page_attribute
(from belong_to)
methods on Page. And you can use the standard create()/new() syntax to
initialize PageAttributes;
just call them on the desired type. Example:

p = Page.new()
p.page_attribute = BooleanPageAttribute.new(options)

etc.

Alternately, you could always use a serialized column to store a typed
object opaquely (see
the discussion in AWDWR, and/or the AR docs). This loses a lot of
searchability, however.

And if you''re stuck with this as a legacy schema, well, we''ll
pray for
you... :)

Hope this helps,
-- 
Matt Jones
mdj.acme-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
President/Technical Director, Acme Art Company (acmeartco.org)


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Rails - Nov 2006 - Yet Another request to help DRY some code

Yet Another request to help DRY some code

Yet Another request to help DRY some code

Yet Another request to help DRY some code

Re: Yet Another request to help DRY some code

Re: Yet Another request to help DRY some code

Re: Yet Another request to help DRY some code

Re: Yet Another request to help DRY some code

Re: Yet Another request to help DRY some code