Find the right object

Rails
1

I have an application where I have a some users, some images, and all
the users can make some personal settings for each image.

I designed my database like this:

Users <–> Settings <—> Images

After googeling on the subject i found out the HABTM not always was the
best solution, I and choose to make Settings to a model.

I can now find the correct Setting-object by doing something like:

@setting = @session[‘user’].settings.find(:first, :conditions =>
[“image_id = ?”, params[:id]])
(where params[:id] = @image.image_id)

this works great as long as the row already exists in the table.
However, since i have about 10.000 images I obviously don’t want to
insert 10.000 new rows every time I add a new user to the system - and
thereby a specific setting might not exist.

I can fix the by doing something like:

@setting = @session[‘user’].settings.find(:first, :conditions =>
[“image_id = ?”, params[:id]])

if not @setting
@setting = Setting.new
@setting.user_id = @session[‘user’].id
@setting.image_id = params[:id]
end

but now it begins to become ugly :confused: isn’t there a cleaner way of doing
this?

2

isn’t there a “find_or_create” function? otherwise maybe adding your own
custom find_or_create method to the settings model would be a cleaner
solution.

3

No - I could not find a find_or_create method. And i din’t understand
how adding it tp the settings model is going to work. Then i need a
settings object to use it, but the idea of the method is to help me find
the settings object

Jeremy W. wrote:

isn’t there a “find_or_create” function? otherwise maybe adding your own
custom find_or_create method to the settings model would be a cleaner
solution.

4

you add it to the model as a class method, so you don’t need an object
to call it on. Then you can call it with
Setting.find_or_create(@session[‘user’], params[:id]) . so in your model
class you’d have something like:

self.find_or_create(user_id, image_id)
ret = Setting.find(:first, :conditions => [“user_id = ? and image_id
= ?”,user_id, image_id])
ret = Setting.create({:user_id => user_id, :image_id => image_id})
if !ret
ret
end

Then you’d always get back a valid object.