:includes with condition - accessing ids

I’m quite new to Rails and I’ve come up against a little problem which
hopefully you guys can shed some light on. I have a multiple select form
element, populated with OIDs associated with a given network devices
(I’m building a small RoR SNMP app). Let me give you a quick run down of
how the models/DB is set up:

“oids” table - fields: id, oid, object, type, description
“devices” table - fields: id, ip, network_id
"devices_oids_ join table - fields: id, device_id, oid_id

The models look something like:

class Device < ActiveRecord::Base
has_many :devices_oid, :dependent => true
has_many :oids, :through => :devices_oid

belongs_to :network
end

class Oid < ActiveRecord::Base
has_many :devices_oid, :dependent => true
has_many :devices, :through => :devices_oid
end

class DevicesOid < ActiveRecord::Base
belongs_to :device
belongs_to :oid
end

To get this up and running, I’ve been using the following in a view:

<% form_tag :action => “remove_oid_from_device” do %>
<%= select_tag(‘oids_to_rem[]’,
options_from_collection_for_select(Oid.find(:all, :include =>
:devices_oid, :conditions => “oids.id = devices_oids.oid_id AND
devices_oids.device_id = #{session[:device_id]}”, :order => “oids.id”),
:id, :object), :multiple => true, :class => “oid_select”) %>
<%= submit_tag ‘Remove OID’ %>

I’ll obviously move this to a model class method later, but for the
moment while testing I’m simply using it in a view.

The problem I’m having is that the above code fragment constructs a
selection form with the value of each selection associated with a given
ID in the “OID” model. What I want to have is for each of these values
to be associated with a given ID from the “DevicesOid”. My first thought
was to change “:id, :object” to “‘devices_oids.id’, object”, but this
doesn’t work. I’m open to any ideas or suggestions you might have since
looking at it right now it appears really ugly.

The problem I’m having is that the above code fragment constructs a
selection form with the value of each selection associated with a given
ID in the “OID” model. What I want to have is for each of these values
to be associated with a given ID from the “DevicesOid”. My first thought
was to change “:id, :object” to “‘devices_oids.id’, object”, but this
doesn’t work. I’m open to any ideas or suggestions you might have since
looking at it right now it appears really ugly.

Instead of:

options_from_collection_for_select(Oid.find(:all, :include =>
:devices_oid, :conditions => “oids.id = devices_oids.oid_id AND
devices_oids.device_id = #{session[:device_id]}”, :order => “oids.id”),
:id, :object)

try this:

options_from_collection_for_select(DevicesOid.find(:all, :conditions =>
[‘device_id = ?’, session[:device_id]], :order => ‘oid_id’), :id,
‘oid.object’)

Nelson


Basedex - A Collaborative Index to organize and collect everything
related to Ruby on Rails
http://blazingrails.basedex.com/index/8

Jason M. wrote:

Nelson,

Thank you for the response! Unfortunately using your snippet throws an
undefined method error for “oid.object”, I’m not entirely sure as to
why.

Any further pointers would be greatly appreciated.

Hmm… in conjunction with my snippet, try adding a wrapper method in
the Devices0id:

def oid_object
oid.object
end

And in the snippet, change ‘oid.object’ to ‘oid_object’

This feels a bit hacky to me, but hopefully it can enable you to keep
going with your project, and hopefully someone will point out the
‘right’ way to do it.

Nelson

Nelson,

Thank you again for the response. There must be something wrong with my
models because adding that wrapper just throws a nil object error. I’ll
post if I find a solution.

Nelson H. wrote:

Jason M. wrote:

Nelson,

Thank you for the response! Unfortunately using your snippet throws an
undefined method error for “oid.object”, I’m not entirely sure as to
why.

Any further pointers would be greatly appreciated.

Hmm… in conjunction with my snippet, try adding a wrapper method in
the Devices0id:

def oid_object
oid.object
end

And in the snippet, change ‘oid.object’ to ‘oid_object’

This feels a bit hacky to me, but hopefully it can enable you to keep
going with your project, and hopefully someone will point out the
‘right’ way to do it.

Nelson

Nelson,

Thank you for the response! Unfortunately using your snippet throws an
undefined method error for “oid.object”, I’m not entirely sure as to
why.

Any further pointers would be greatly appreciated.

Nelson H. wrote:

The problem I’m having is that the above code fragment constructs a
selection form with the value of each selection associated with a given
ID in the “OID” model. What I want to have is for each of these values
to be associated with a given ID from the “DevicesOid”. My first thought
was to change “:id, :object” to “‘devices_oids.id’, object”, but this
doesn’t work. I’m open to any ideas or suggestions you might have since
looking at it right now it appears really ugly.

Instead of:

options_from_collection_for_select(Oid.find(:all, :include =>
:devices_oid, :conditions => “oids.id = devices_oids.oid_id AND
devices_oids.device_id = #{session[:device_id]}”, :order => “oids.id”),
:id, :object)

try this:

options_from_collection_for_select(DevicesOid.find(:all, :conditions =>
[‘device_id = ?’, session[:device_id]], :order => ‘oid_id’), :id,
‘oid.object’)

Nelson


Basedex - A Collaborative Index to organize and collect everything
related to Ruby on Rails
http://blazingrails.basedex.com/index/8

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