Rails - Jan 2008 - using object.find() in a loop not returning an array

I''m running a loop (illustrated below) that retrieves records from a
table based on an id that might be different with each iteration.  The
loop uses the array scrns (composed of IDs) to find the related records
in the Screens table.  I''m attempting to store the returned results in
an instance variable so I can use that data in a view.  However, this
code simply is overwriting the instance variable with each iteration.
Why?  I want to end up with an array or hash in the instance var so I
can iterate through it in my view to display.

***CODE****
for scr in scrns
  @scrs = Screen.find(:all, :conditions => [ "id = ?",
scr.screen_id ])
end
***CODE****

I''ve tried modifying the statement above in multiple ways:

***CODE****
@scrs << Screen.find( blah blah

@scrs += Screen.find( blah blah

Screen.find( blah blah).collect blah
***CODE****

Nothing is working.  Any ideas?
-- 
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On 24 Jan 2008, at 17:25, Corey Murphy wrote:
>
> I''m running a loop (illustrated below) that retrieves records from
a
> table based on an id that might be different with each iteration.  The
> loop uses the array scrns (composed of IDs) to find the related  
> records
> in the Screens table.  I''m attempting to store the returned
results in
> an instance variable so I can use that data in a view.  However, this
> code simply is overwriting the instance variable with each iteration.
> Why?  I want to end up with an array or hash in the instance var so I
> can iterate through it in my view to display.
>
> ***CODE****
> for scr in scrns
>  @scrs = Screen.find(:all, :conditions => [ "id = ?",
scr.screen_id ])
> end
> ***CODE****
>
> I''ve tried modifying the statement above in multiple ways:
>
This is all pretty much basic ruby. You''ll save yourself a lot of  
frustration by reading up on this sort of stuff and getting well  
acquainted with ruby itself.
> ***CODE****
> @scrs << Screen.find( blah blah
would work if you initially set @scrs to []
>
> @scrs += Screen.find( blah blah
would also work if you initially set @scrs to [], but wouldn''t do the  
same thing as <<. (I''m guessing the previous version does what
you
actually want)
> Screen.find( blah blah).collect blah
scrns.collect {|scr| Screen.find :all, :conditions =>[ "id = ?",  
scr.screen_id ])

Fred
>
> ***CODE****
>
> Nothing is working.  Any ideas?
> -- 
> Posted via http://www.ruby-forum.com/.
>
> >

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Frederick Cheung wrote:
> On 24 Jan 2008, at 17:25, Corey Murphy wrote:
> 
>>
>> ***CODE****
>> for scr in scrns
>>  @scrs = Screen.find(:all, :conditions => [ "id = ?",
scr.screen_id ])
>> end
>> ***CODE****
>>
>> I''ve tried modifying the statement above in multiple ways:
>>
> This is all pretty much basic ruby. You''ll save yourself a lot of
> frustration by reading up on this sort of stuff and getting well
> acquainted with ruby itself.
>> ***CODE****
>> @scrs << Screen.find( blah blah
> would work if you initially set @scrs to []
>>
>> @scrs += Screen.find( blah blah
> would also work if you initially set @scrs to [], but wouldn''t do
the
> same thing as <<. (I''m guessing the previous version does
what you
> actually want)
> 
>> Screen.find( blah blah).collect blah
> 
> scrns.collect {|scr| Screen.find :all, :conditions =>[ "id =
?",
> scr.screen_id ])
> 
> Fred
Thanks Fred,

Good to know I''m not going crazy.  I had tried your first suggestion 
last night, but I''ve apparently not been looking carefully enough at my
error. My error is in how I''m attempting to access the values in the 
view. However treating @scrs as an array and then iterating through it 
is still returning me a error of the following:

***CODE***
<% for scrs in @scrs %>
  <tr>
    <td><%= scrs.id %></td>
    <td><%= scrs.title %></td>
  </tr>
<% end %>

***ERROR***
undefined method `title'' for [#<Screen id: 2, title: "Test
Screen
Title">]:Array

I''m assuming I have an array @scrs which contains a hash for each
record
that was stored in each array indice.  So how would I go about accessing 
a hash key value pair from within an array?

scrs[''title''] maybe?
OR
scrs[:title]

Thanks again for your help.
-- 
Posted via http://www.ruby-forum.com/.

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Nevermind I figured it out.

Thanks again for the help Fred.
-- 
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On Jan 24, 2008, at 1:25 PM, Corey Murphy wrote:
> Frederick Cheung wrote:
>> On 24 Jan 2008, at 17:25, Corey Murphy wrote:
>>> ***CODE****
>>> for scr in scrns
>>> @scrs = Screen.find(:all, :conditions => [ "id = ?",  
>>> scr.screen_id ])
>>> end
>>> ***CODE****
>>>
>>> I''ve tried modifying the statement above in multiple ways:
>>>
>> This is all pretty much basic ruby. You''ll save yourself a lot
of
>> frustration by reading up on this sort of stuff and getting well
>> acquainted with ruby itself.
If scrns looks something like [ 123, 456, 987, 534 ], that is, a  
simple array of integers, then you just need to say:

   @scrs = Screen.find(scrns)
>>> ***CODE****
>>> @scrs << Screen.find( blah blah
>> would work if you initially set @scrs to []
>>>
>>> @scrs += Screen.find( blah blah
>> would also work if you initially set @scrs to [], but wouldn''t
do the
>> same thing as <<. (I''m guessing the previous version
does what you
>> actually want)
>>
>>> Screen.find( blah blah).collect blah
>>
>> scrns.collect {|scr| Screen.find :all, :conditions =>[ "id =
?",
>> scr.screen_id ])
>>
>> Fred
>
> Thanks Fred,
>
> Good to know I''m not going crazy.  I had tried your first
suggestion
> last night, but I''ve apparently not been looking carefully enough
at
> my
> error. My error is in how I''m attempting to access the values in
the
> view. However treating @scrs as an array and then iterating through it
> is still returning me a error of the following:
>
> ***CODE***
> <% for scrs in @scrs %>
>  <tr>
>    <td><%= scrs.id %></td>
>    <td><%= scrs.title %></td>
>  </tr>
> <% end %>
>
> ***ERROR***
> undefined method `title'' for [#<Screen id: 2, title: "Test
Screen
> Title">]:Array
>
> I''m assuming I have an array @scrs which contains a hash for each
> record
> that was stored in each array indice.  So how would I go about  
> accessing
> a hash key value pair from within an array?
>
> scrs[''title''] maybe?
> OR
> scrs[:title]
>
> Thanks again for your help.

I think you just need to try my first suggestion (if the assumption is  
accurate).

Since find(:all, ...) is going to return something that behaves like  
an array, you probably need to flatten the results:

<% for scrn in @scrs.flatten %>
   <tr>
     <td><%= scrn.id %></td>
     <td><%= scrn.title %></td>
   </tr>
<% end %>

-Rob

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




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