Rails - May 2010 - to "loop through" the instance variables of ActiveRecord?

to wrap each instance variable of an ActiveRecord object between
"<td>"
and "</td>", is there a way to "loop through" them, at
least in the
debug mode, no matter there is getter methods to get them or not, or at
least the ones with the getter methods?

Such as

<% @stories.each do |s| %>
  <%= "<tr>" %>
  <% s.each_property do |i| %>
    <%= "<td>#{h i}</td>\n" %>
  <% end %>
  <%= "</tr>\n" %>
<% end %>

?
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> to wrap each instance variable of an ActiveRecord object between
"<td>"
> and "</td>", is there a way to "loop through"
them, at least in the
> debug mode, no matter there is getter methods to get them or not, or at
> least the ones with the getter methods?
> 
> Such as
> 
> <% @stories.each do |s| %>
>  <%= "<tr>" %>
>  <% s.each_property do |i| %>
>    <%= "<td>#{h i}</td>\n" %>
>  <% end %>
>  <%= "</tr>\n" %>
> <% end %>
@stories.attributes....

http://api.rubyonrails.org/classes/ActiveRecord/Base.html#M002348

-philip

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Philip Hallstrom wrote:
>>    <%= "<td>#{h i}</td>\n" %>
>>  <% end %>
>>  <%= "</tr>\n" %>
>> <% end %>
> 
> @stories.attributes....
> 
> http://api.rubyonrails.org/classes/ActiveRecord/Base.html#M002348
> 
> -philip
Great thanks.

So I have come up something like this:

the row == 1 check is to print the header

<style>
  table { border-collapse: collapse }
  td, th { border: 1px solid #ccc; padding: 0.33em }
  th { background: #eee }
</style>

<%= "<table>\n" %>
<% row = 1 %>
<% @all_stories.each do |s| %>
  <% if row == 1 %>
    <%= "<tr>" %>
    <% s.attributes.each do |i| %>
    <% p i %>
    <%= "<th>#{h i[0]}</th>\n" %>
    <% end %>
    <%= "</tr>\n" %>
  <% end %>

  <%= "<tr>" %>
  <% s.attributes.each do |i| %>
  <% p i %>
  <%= "<td>#{h i[1]}</td>\n" %>
  <% end %>
  <%= "</tr>\n" %>

  <% row += 1 %>
<% end %>

<%= "</table>\n" %>


it might be better if the internal loop counter can be used for looping 
@all_stories so that now extra local variable "row" is needed.

also, the use of i[0], i[1] seems a little less structured than if 
i.attr_name, i.attr_value can be used.

the row == 1 situation also seems like somewhat not adhering to DRY.

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On May 13, 2010, at 2:51 PM, Jian Lin wrote:
> Philip Hallstrom wrote:
>>>   <%= "<td>#{h i}</td>\n" %>
>>> <% end %>
>>> <%= "</tr>\n" %>
>>> <% end %>
>> 
>> @stories.attributes....
>> 
>> http://api.rubyonrails.org/classes/ActiveRecord/Base.html#M002348
>> 
>> -philip
> 
> Great thanks.
> 
> So I have come up something like this:
> 
> the row == 1 check is to print the header
> 
> <style>
>  table { border-collapse: collapse }
>  td, th { border: 1px solid #ccc; padding: 0.33em }
>  th { background: #eee }
> </style>
> 
> <%= "<table>\n" %>
> <% row = 1 %>
> <% @all_stories.each do |s| %>
>  <% if row == 1 %>
>    <%= "<tr>" %>
>    <% s.attributes.each do |i| %>
>    <% p i %>
>    <%= "<th>#{h i[0]}</th>\n" %>
>    <% end %>
>    <%= "</tr>\n" %>
>  <% end %>
> 
>  <%= "<tr>" %>
>  <% s.attributes.each do |i| %>
>  <% p i %>
>  <%= "<td>#{h i[1]}</td>\n" %>
>  <% end %>
>  <%= "</tr>\n" %>
> 
>  <% row += 1 %>
> <% end %>
> 
> <%= "</table>\n" %>
> 
> 
> it might be better if the internal loop counter can be used for looping 
> @all_stories so that now extra local variable "row" is needed.
I''m not sure that attributes() returns an ordered hash.  That is, for
each iteration you might get the fields in a different order.  You should check
that.

> also, the use of i[0], i[1] seems a little less structured than if 
> i.attr_name, i.attr_value can be used.
look into "s.attributes.each_pair |k,v|"

> the row == 1 situation also seems like somewhat not adhering to DRY.
You could consider using Story.column_names to print out the header and then
using that to loop through and print out each object''s attributes...

-philip

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Philip Hallstrom wrote:
>> also, the use of i[0], i[1] seems a little less structured than if 
>> i.attr_name, i.attr_value can be used.
> 
> look into "s.attributes.each_pair |k,v|"
> 
> 
>> the row == 1 situation also seems like somewhat not adhering to DRY.
> 
> You could consider using Story.column_names to print out the header and 
> then using that to loop through and print out each object''s 
> attributes...
> 
> -philip
yes, column_names gave a better order:

C:\Software Projects\ror\shov10>ruby script/console
Loading development environment (Rails 2.3.5)
>> Story.column_names
=> ["id", "name", "link",
"created_at", "updated_at"]

s.attributes came in the order of:

name  created_at  updated_at  id  link

with the primary index somewhere in the middle.
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On May 13, 2010, at 3:47 PM, Jian Lin wrote:
> Philip Hallstrom wrote:
> 
>>> also, the use of i[0], i[1] seems a little less structured than if 
>>> i.attr_name, i.attr_value can be used.
>> 
>> look into "s.attributes.each_pair |k,v|"
>> 
>> 
>>> the row == 1 situation also seems like somewhat not adhering to
DRY.
>> 
>> You could consider using Story.column_names to print out the header and
>> then using that to loop through and print out each object''s 
>> attributes...
>> 
>> -philip
> 
> yes, column_names gave a better order:
> 
> C:\Software Projects\ror\shov10>ruby script/console
> Loading development environment (Rails 2.3.5)
>>> Story.column_names
> => ["id", "name", "link",
"created_at", "updated_at"]
> 
> s.attributes came in the order of:
> 
> name  created_at  updated_at  id  link
> 
> with the primary index somewhere in the middle.
In either case however, make *sure* that the order they come in is consistent. 
Hashes by default do not guarantee any order when looping through them.

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Jian Lin wrote:
> yes, column_names gave a better order:
> 
> C:\Software Projects\ror\shov10>ruby script/console
> Loading development environment (Rails 2.3.5)
>>> Story.column_names
> => ["id", "name", "link",
"created_at", "updated_at"]

so the code can be:

<style>
  table { border-collapse: collapse }
  td, th { border: 1px solid #ccc; padding: 0.33em }
  th { background: #eee }
  tr:hover { background: #eee }
</style>

<%= "<p><p><p><table>\n" %>
<% row = 1 %>
<% @all_stories.each do |s| %>
  <% if row == 1 %>
    <%= "<tr>" %>
    <% @column_names.each do |i| %>
    <%= "<th>#{h i}</th>\n" %>
    <% end %>
    <%= "</tr>\n" %>
  <% end %>

  <%= "<tr>" %>
  <% @column_names.each do |k| %>
  <%= "<td>#{h s.attributes[k]}</td>\n" %>
  <% end %>
  <%= "</tr>\n" %>

  <% row += 1 %>
<% end %>

<%= "</table>\n" %>

I found that either

  s.attributes[k]

or

  s.send(k)

can be used.  the second one is to invoke the getter method and it gave 
a slight different version of the datetime object.

kind of interesting that in script/console, i get
>> s.created_at
=> Thu, 13 May 2010 09:22:50 UTC +00:00
>> s.send("created_at")
=> Thu, 13 May 2010 09:22:50 UTC +00:00

but on the webpage, i get a different format:

2010-05-13 09:23:58 UTC

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