Object.find in HABTM join table?

Good morning,

is it possible to find objects by giving values for the HABTM join table
only?

Example:
menu
id name parents path
1 abc -1 /
2 def 1 /def
3 ghi 1 /ghi
4 jkl 2,1 /jkl
5 mno 2 /mno

that means when I go to /abc the menu consists of menu items with the id
2, 3 and 4. When I go to /def the menu consits of the menu items with
the id 4 and 5 but as you can see menu items can be shown in many menus
but exist only once.

So the tables would look like this:
menus
id name path
1 abc /
2 def /def
3 ghi /ghi
4 jkl /jkl
5 mno /mno

menus_parents
menu_id parent_id
2 1
3 1
4 1
4 2
5 2

So how is it possible to all menu objects that have 1 as parent?
My current approach is:
menus = Menu.all
menus = menus.select{|m| m.parents.include?(1)}

I don't really like it cause all menu items are loaded from the database
each and every time. Is there any better solution to this like some
find...?

Good morning,

is it possible to find objects by giving values for the HABTM join table
only?

Example:
menu
id name parents path
1 abc -1 /
2 def 1 /def
3 ghi 1 /ghi
4 jkl 2,1 /jkl
5 mno 2 /mno

that means when I go to /abc the menu consists of menu items with the id
2, 3 and 4. When I go to /def the menu consits of the menu items with
the id 4 and 5 but as you can see menu items can be shown in many menus
but exist only once.

So the tables would look like this:
menus
id name path
1 abc /
2 def /def
3 ghi /ghi
4 jkl /jkl
5 mno /mno

menus_parents
menu_id parent_id
2 1
3 1
4 1
4 2
5 2

So how is it possible to all menu objects that have 1 as parent?
My current approach is:
menus = Menu.all
menus = menus.select{|m| m.parents.include?(1)}

Can't you do
menus = Menu.find( :all, :include => :parents, :conditions =>
['parent.id = ?, 1] )
or something similar.

Or even better, if you have the parent object, then all the menus that
have that as a parent are parent.menus

Colin

Hey Colin,

thanks but the parent.menus doesn't work because the habtm is on the
same table:
has_and_belongs_to_many :parents, :class_name => "Menu",
:association_foreign_key => "parent_id", :join_table => "menus_parents"

The other suggestion works just fine, thanks!

This is the working code:
@menus = Menu.find(:all, :include => :parents, :conditions =>
['`menus_parents`.parent_id = ?', parent.id])

Hey Colin,

thanks but the parent.menus doesn't work because the habtm is on the
same table:
has_and_belongs_to_many :parents, :class_name => "Menu",
:association_foreign_key => "parent_id", :join_table => "menus_parents"

I think there may be a better way of doing this. If you made the join
table a proper table with a model then for Menu you could do
has_many children through menus_parents
and also
has_many parents through menus_parents
then you can go both ways more easily.

Colin