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michael_teter

2009-Jan-09 16:42 UTC

Confused about to_xml() in ActiveRecord::Base subclass

Since all my efforts to control how to_xml() is formatting dates has
failed, I''m now considering writing my own to_xml().  However, from
the limited examples I''ve found, I just don''t understand how
to
actually reference the columns for the records in my record set.

Here''s a simplified view of my ActiveRecord object:

class Errors < ActiveRecord::Base
  set_table_name "legacy_errors"

  # legacy_errors has three columns: id, msg, error_date
  # Since the default to_xml is generating error_dates in the format
"Mon Nov 03 00:00:00 -0600 2008",
  #    and I cannot seem to force a different behavior, I want to
create my own to_xml.

  # Examples online show the following as how to override to_xml:
    def to_xml(options = {})
      options[:indent] ||= 2
      xml = options[:builder] ||= Builder::XmlMarkup.new(:indent =>
options[:indent])
      xml.instruct! unless options[:skip_instruct]
      # v v v
      xml.level_one do
        xml.tag!(:second_level, ''content'')
      end
      # ^ ^ ^
    end
end

The code between the v and ^ markers is where the body of each XML
object is generated.  If I were generating by hand, I would do
something like this:
errors.each do |err|
  s << "<id>" << err.id <<
"</id>"
  s << "<msg>" << err.msg <<
"</msg>"
  s << "<error_date>" <<
err.error_date.strftime("%Y-%m-%d") << "</
error_date>"
end

I''m not at all understanding how to do my thing within the v ^ section
of to_xml().

Any help is appreciated!

Thanks.
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Rob Biedenharn

2009-Jan-09 17:20 UTC

head link

Re: Confused about to_xml() in ActiveRecord::Base subclass

On Jan 9, 2009, at 11:42 AM, michael_teter wrote:> Since all my efforts to control how to_xml() is formatting dates has
> failed, I''m now considering writing my own to_xml().  However,
from
> the limited examples I''ve found, I just don''t understand
how to
> actually reference the columns for the records in my record set.
>
> Here''s a simplified view of my ActiveRecord object:
>
> class Errors < ActiveRecord::Base
>  set_table_name "legacy_errors"
>
>  # legacy_errors has three columns: id, msg, error_date
>  # Since the default to_xml is generating error_dates in the format
> "Mon Nov 03 00:00:00 -0600 2008",
>  #    and I cannot seem to force a different behavior, I want to
> create my own to_xml.
>
>  # Examples online show the following as how to override to_xml:
>    def to_xml(options = {})
>      options[:indent] ||= 2
>      xml = options[:builder] ||= Builder::XmlMarkup.new(:indent =>
> options[:indent])
>      xml.instruct! unless options[:skip_instruct]
>      # v v v
>      xml.level_one do
>        xml.tag!(:second_level, ''content'')
>      end
>      # ^ ^ ^
>    end
> end
>
> The code between the v and ^ markers is where the body of each XML
> object is generated.  If I were generating by hand, I would do
> something like this:
> errors.each do |err|
>  s << "<id>" << err.id <<
"</id>"
>  s << "<msg>" << err.msg <<
"</msg>"
>  s << "<error_date>" <<
err.error_date.strftime("%Y-%m-%d") << "</
> error_date>"
> end
>
> I''m not at all understanding how to do my thing within the v ^
section
> of to_xml().
>
> Any help is appreciated!
>
> Thanks.

that should be the encoding of a single Errors instance.

   xml.error do |x|
     x.id(self.id)
     x.msg(self.msg)
     x.error_date(self.error_date.strftime(''%Y-%m-%d''))
   end

I think that you''d get a bunch of errors with:

   Errors.find(:all, :conditions => [...]).to_xml(:root =>
''errors'')

By default, I get output of attributes like this:
     <created-at
type="datetime">2009-01-09T02:58:31Z</created-at>
     <id type="integer">110</id>
     <reference>From Anne</reference>
When I do #to_xml.  Notice the date format for the type="datetime".   
What is the actual class of error_date?  Is it a Date or a DateTime or  
a Time?

-Rob

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



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michael_teter

2009-Jan-09 18:01 UTC

head link

Re: Confused about to_xml() in ActiveRecord::Base subclass

Rob,

Thanks much for the good response.

To answer your question about the data type, it''s "date" in
Oracle.
When I use the default to_xml() (without suppressing types and the
dasherizer) it looks like this:
<error-date type=\"ActiveRecord::ConnectionAdapters::OracleColumn
\">Wed Nov 12 00:00:00 -0600 2008</error-date>

In fact, every element is listed as "OracleColumn".  I did try the
following to control my date presentation:
      proc = Proc.new {|options| options[:builder].tag!
(''error_date_x'',
options[:object].error_date.strftime("%Y-%m-%d"))}
      s = errs.to_xml(:dasherize => false, :skip_types => true, :procs
=> [proc])
That just blows up.
NoMethodError: You have a nil object when you didn''t expect it!
The error occurred while evaluating nil.error_date

What''s really odd is I''ve been using the default to_xml() for
months
and receiving "YYYY-MM-DD" as my format.  Now suddenly I''m
getting a
different format.  Perhaps I updated gems and got something new...

So now, if I cannot simply control the formatting of that one column,
I''ll do my own to_xml() (following your example).

On Jan 9, 11:20 am, Rob Biedenharn
<R...-xa9cJyRlE0mWcWVYNo9pwxS2lgjeYSpx@public.gmane.org>
wrote:> On Jan 9, 2009, at 11:42 AM, michael_teter wrote:
>
>
>
> > Since all my efforts to control how to_xml() is formatting dates has
> > failed, I''m now considering writing my own to_xml().
 However, from
> > the limited examples I''ve found, I just don''t
understand how to
> > actually reference the columns for the records in my record set.
>
> > Here''s a simplified view of my ActiveRecord object:
>
> > class Errors < ActiveRecord::Base
> >  set_table_name "legacy_errors"
>
> >  # legacy_errors has three columns: id, msg, error_date
> >  # Since the default to_xml is generating error_dates in the format
> > "Mon Nov 03 00:00:00 -0600 2008",
> >  #    and I cannot seem to force a different behavior, I want to
> > create my own to_xml.
>
> >  # Examples online show the following as how to override to_xml:
> >    def to_xml(options = {})
> >      options[:indent] ||= 2
> >      xml = options[:builder] ||= Builder::XmlMarkup.new(:indent =>
> > options[:indent])
> >      xml.instruct! unless options[:skip_instruct]
> >      # v v v
> >      xml.level_one do
> >        xml.tag!(:second_level, ''content'')
> >      end
> >      # ^ ^ ^
> >    end
> > end
>
> > The code between the v and ^ markers is where the body of each XML
> > object is generated.  If I were generating by hand, I would do
> > something like this:
> > errors.each do |err|
> >  s << "<id>" << err.id <<
"</id>"
> >  s << "<msg>" << err.msg <<
"</msg>"
> >  s << "<error_date>" <<
err.error_date.strftime("%Y-%m-%d") << "</
> > error_date>"
> > end
>
> > I''m not at all understanding how to do my thing within the v
^ section
> > of to_xml().
>
> > Any help is appreciated!
>
> > Thanks.
>
> that should be the encoding of a single Errors instance.
>
>    xml.error do |x|
>      x.id(self.id)
>      x.msg(self.msg)
>      x.error_date(self.error_date.strftime(''%Y-%m-%d''))
>    end
>
> I think that you''d get a bunch of errors with:
>
>    Errors.find(:all, :conditions => [...]).to_xml(:root =>
''errors'')
>
> By default, I get output of attributes like this:
>      <created-at
type="datetime">2009-01-09T02:58:31Z</created-at>
>      <id type="integer">110</id>
>      <reference>From Anne</reference>
> When I do #to_xml.  Notice the date format for the
type="datetime".  
> What is the actual class of error_date?  Is it a Date or a DateTime or  
> a Time?
>
> -Rob
>
> Rob Biedenharn          http://agileconsultingllc.com
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