has_many, find_all problem

rubyonrails-talk
1

ruby 1.8.5, Rails 1.2.1 Caution - I'm a ruby noob.

I have 2 models - Meeting and Meeting_Items. As you would expect a meeting has_many :meeting_items and a meeting_item belongs_to :meeting.

When trying to use find_all to return an array which only includes "agenda items" I found that it always returned the full array of meeting_items. To try to find the fault I have reduced the problem to its' simplest form that still gives me the problem.

@meeting.meeting_items.find_all{ |m| false}

The code above still returns the full array of meeting_items for the meeting, I would expect it to return an empty array.

When I do the following I get an empty array returned, which is what I expect. [1,2,3,4,5].find_all{|x| false}

Any help appreciated.

Reed

2

ruby 1.8.5, Rails 1.2.1 Caution - I’m a ruby noob.

I have 2 models - Meeting and Meeting_Items. As you would expect a meeting has_many :meeting_items and a meeting_item belongs_to :meeting.

When trying to use find_all to return an array which only includes “agenda items” I found that it always returned the full array of meeting_items. To try to find the fault I have reduced the problem to its’ simplest

form that still gives me the problem.

@meeting.meeting_items.find_all{ |m| false}

The find_all is an Array method but meeting_items is not strictly an array even though it behaves a bit like one. The find all on a collection of AR models is a depricated method. Intead you should use find(:all, :conditions => … )

The code above still returns the full array of meeting_items for the

meeting, I would expect it to return an empty array.

When I do the following I get an empty array returned, which is what I expect. [1,2,3,4,5].find_all{|x| false}

Any help appreciated.

Reed I think there are a couple of ways to achive this functionality i think you’re looking for…

Using Meeting.find(:all, :conditions => { :field => ‘value’ } )

Or you can set this up in the meeting class as a has_many

class Meeting < AR::B has_many :meeting_items has_many :agenda_items, :class_name => ‘meeting_item’, :conditions => “field=‘value’” end

then call this by

@meeting.agenda_items

I hope this helps.

3

Wow, thanks for the info.

has_many :agenda_items, :class_name => 'meeting_item', :conditions =>

... is exactly what I am after but I was implementing it in a lame manner, when compared to this solution.

Cheers, Reed

4

another thing you might want to look into is using association extensions

has_many :items, :class_name => 'meeting_item' do   def agendas     find(:all, :conditions => ...)   end

  def some_other_type     find(:all, :conditions => ...)   end end

what's nice about this is you can now say

# all meeting items meeting.items

# all agenda meeting items meeting.items.agendas

# all 'some_other_type' items meeting.items.some_other_type