From: Josh Cheek <josh.cheek@...>
Date: 2011-09-03T22:53:07+09:00
Subject: Re: help on find over find

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On Thu, Jan 20, 2011 at 5:05 PM, Mauricio Alcayaga <gusantor@hotmail.com>wrote:

> class User < ActiveRecord::Base
>  has_many :requests
> end
>
> finally at view:
> <%= yearsCalendar(User.requests) # WORKS FINE %>
>
>
This doesn't make sense, an instance of user should have a method
`requests`, but not the user class itself. I assume this code doesn't
actually work, or it works for some unrelated reason (maybe there is a
method requests defined on ActiveRecord::Base or something)


On Thu, Jan 20, 2011 at 5:05 PM, Mauricio Alcayaga <gusantor@hotmail.com>
 wrote:

> class Request < ActiveRecord::Base
>  def unRequested
>  find(:all, conditions => {:state => "unrequested"})
>  end
> end
>
> <%= yearsCalendar(Request.unRequested) #WONT WORK , RETURN ERROR:
> "LocalJumpError: no block given" %>
>
>
This also doesn't make sense, for the same reason. unRequested is an
instance method, not a class method. It should be `def self.unRequested`



Anyway, I think Eric probably had it right.
http://api.rubyonrails.org/classes/ActiveRecord/FinderMethods.html#method-i-findit
says that all returns an array. There should be a way to return a lazy
finder object that you can then add further queries to, but I don't really
feel like loading Rails up to figure it out (I'd start by looking here
http://guides.rubyonrails.org/active_record_querying.html). But you don't
want to be creating in memory arrays and then using Ruby's collection
methods, that is not a scalable solution.


On Sat, Sep 3, 2011 at 8:07 AM, Mauricio Alcayaga <gusantor@hotmail.com>
 wrote:

> Ryan Davis wrote in post #1019657:
> > On Sep 1, 2011, at 11:31 , Mauricio Alcayaga wrote:
> >
> >> @activityPeriods = coleccion.map{ |x| [x.VARIABLEFIELDNAME.year,
> >> x.VARIABLEFIELDNAME.month] }.uniq
> >
> > I'm not sure I entirely understand your question... but I think you want
> > to look at Object.send.
>
> thank you Ryan
>
> anyway, a friend of mine, cristian (zany) zaninovic, gently answer me,
> he spoke as: hey bastard, you should use :
>
> paramA = 'year'
> paramB = 'month'
> dateFieldName = 'name_of_da_field'
> @activityPeriods = coleccion.map{ |x|
> [eval("x.#{dateFieldName}.#{paramA}"),
> eval("x.#{dateFieldName}.#{paramB}")] }.uniq
>
> I didn't try already, but think it will work
>
> --
> Posted via http://www.ruby-forum.com/.
>
>
This is a bad plan. First, you should be selecting these objects through
ActiveRecord's query interface. Second, even if you want to use Ruby's
collection methods like #map and #uniq, you should do what Ryan said and use
send:

[x.send("name_of_da_field", "year"), x.send("name_of_da_field", "month")]

This will be faster because you don't have to parse Ruby code, and it will
be safer because there's no possibility of accidentally evaluating arbitrary
code.

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