Rails - May 2006 - noobie activerecord find query

In my webapp a todolist has many todo items. I am trying to display
lists that are completed. By incomplete I mean that all the items in
that list are done (booolean = true). I hope to have a list of active
lists and complete lists on one page.
I''m no ruby expert by any means so I think I have to
''pipe'' some results
into another query??

Can you help please?

-- 
Posted via http://www.ruby-forum.com/.

So you want to populate an instance variable with all the items which are
done, basically. Here we go:

@todos = Todo.find(:all, :conditions => ''done = Y'')

(or whatever the flag for done is).

Alternatively, you could use

@todos = Todo.find_all_by_done(''Y'')

but the former will probably get you into better habits.

It''s not a Ruby problem at all, it''s basic database stuff.
There''s no need
to "pipe" anything to a second query, it''s a basic WHERE
clause.

How much do you know about development, and SQL in particular? You might
find Rails pretty rough going if this is tricky, just as a warning.

t.

On 10/05/06, James Whittaker <jmwhittaker@gmail.com>
wrote:
>
> In my webapp a todolist has many todo items. I am trying to display
> lists that are completed. By incomplete I mean that all the items in
> that list are done (booolean = true). I hope to have a list of active
> lists and complete lists on one page.
> I''m no ruby expert by any means so I think I have to
''pipe'' some results
> into another query??
>
> Can you help please?
>
> --
> Posted via http://www.ruby-forum.com/.
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>
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Tom Armitage wrote:
> So you want to populate an instance variable with all the items which 
> are
> done, basically. Here we go:
> 
> @todos = Todo.find(:all, :conditions => ''done = Y'')
> 
> (or whatever the flag for done is).
> 
> Alternatively, you could use
> 
> @todos = Todo.find_all_by_done(''Y'')
> 
> but the former will probably get you into better habits.
> 
> It''s not a Ruby problem at all, it''s basic database
stuff. There''s no
> need
> to "pipe" anything to a second query, it''s a basic WHERE
clause.
> 
> How much do you know about development, and SQL in particular? You might
> find Rails pretty rough going if this is tricky, just as a warning.
> 
> t.
Thanks, sorry probably did not explain it correctly. My todo_list Has 
Manay todo_items. each item has a done flag (boolean). A todo_list 
becomes complete when all of its todo_items are marked as done, 
otherwise it is not done. The todo_list does not have a done field in 
the database.


-- 
Posted via http://www.ruby-forum.com/.

OK, try pasting the following into your Todo_list model (todo_list.rb)
at the top

has_many :completed_items,
         :class_name => ''Todo_item'',
         :conditions => ''done is not null''

def completed?
   if self.todo_items == self.completed_items
       true
   else
       false
   end
end

Then you''ll find that Todo_list.completed? should return
''true'' if all
the items are completed, and false if not. So now you can seperate out
completed and uncompleted lists

I think that''ll work, anyhow. If it does, do you understand why?

(Hope you didn''t think I was condescending last time).

Tom Armitage wrote:
> OK, try pasting the following into your Todo_list model (todo_list.rb)
> at the top
> 
> has_many :completed_items,
>          :class_name => ''Todo_item'',
>          :conditions => ''done is not null''
> 
> def completed?
>    if self.todo_items == self.completed_items
>        true
>    else
>        false
>    end
> end
> 
> Then you''ll find that Todo_list.completed? should return
''true'' if all
> the items are completed, and false if not. So now you can seperate out
> completed and uncompleted lists
> 
> I think that''ll work, anyhow. If it does, do you understand why?
> 
> (Hope you didn''t think I was condescending last time).
Thanks for the help. It is very similar to what I have in the model 
already:
def complete?
	   todo_items.each do |todoitem|
	      return false if not taskitem.done?
	   end
	   true
	end

What I was trying to do was get a has of each like this:

@active_lists = TodoList.find(:all,

@completed_lists = TodoList.find(:all,

The only way I can guess to do it it to return all the todolists then 
ittterate over them one by one and add them to an 2 new arrays. Seems a 
little complex. I need two variables because of the way the view is 
listing them out.

-- 
Posted via http://www.ruby-forum.com/.

Aha.

OK, try this: you could set a new field in your database/model called
"done". Then what you do is you have an ActiveRecord observer watch
the model, and every time one of its Todo_items gets marked as done,
the observer checks if they''re all done, and if they''re all
done, it
sets Todo_list.done to be true. If any of them change status, it
unsets the done status on the list.

Then you CAN just say @active_list = TodoList.find_all(:conditions =>
"done is not null").

You could either use an observer or a callback on before_save. Have a
look in the agile book or the API documentation - off the top of my
head, I can''t help you.

You don''t need two variables for your view necessarily, but
it''s
better practice to have them.

I think this is getting near solving your problem: the extra field in
the DB will make the app so much faster, but you don''t have to worry
about updating it, you can make it update itself.

Tom Armitage wrote:
> Aha.
> 
> OK, try this: you could set a new field in your database/model called
> "done". Then what you do is you have an ActiveRecord observer
watch
> the model, and every time one of its Todo_items gets marked as done,
> the observer checks if they''re all done, and if they''re
all done, it
> sets Todo_list.done to be true. If any of them change status, it
> unsets the done status on the list.
> 
> Then you CAN just say @active_list = TodoList.find_all(:conditions =>
> "done is not null").
> 
> You could either use an observer or a callback on before_save. Have a
> look in the agile book or the API documentation - off the top of my
> head, I can''t help you.
> 
> You don''t need two variables for your view necessarily, but
it''s
> better practice to have them.
> 
> I think this is getting near solving your problem: the extra field in
> the DB will make the app so much faster, but you don''t have to
worry
> about updating it, you can make it update itself.
Tom, thats brilliant. I am just looking again at the Agile book trying 
to get my head around the observers. It may take a while. (page 280 
onwards).

Tell me Tom, could this help with my other problem I have looming. I 
have an overview page that is going to list each of the users projects 
and underneath each project there will be a list of the latest 10 
updated/created items. These items will be from one of 4 ActiveRecord 
models (like messages, todos, tickets) I was trying to work oyt how to 
query each project then find the top 10 for each of the has_maany items, 
then re iterate over the array of results ordering them in date order. 
This would be for each project. Similar to basecamps dashboard (in 
function anyway). This is the next hurdle! Would your suggestion here 
help as well?

-- 
Posted via http://www.ruby-forum.com/.

> Tom, thats brilliant. I am just looking again at the Agile book trying
> to get my head around the observers. It may take a while. (page 280
> onwards).
>
> Tell me Tom, could this help with my other problem I have looming. I
> have an overview page that is going to list each of the users projects
> and underneath each project there will be a list of the latest 10
> updated/created items. These items will be from one of 4 ActiveRecord
> models (like messages, todos, tickets) I was trying to work oyt how to
> query each project then find the top 10 for each of the has_maany items,
> then re iterate over the array of results ordering them in date order.
> This would be for each project. Similar to basecamps dashboard (in
> function anyway). This is the next hurdle! Would your suggestion here
> help as well?
>
OK. So one thing to consider is Single Table Inheritance; if the
"items" users are fairly similar, you could store them in a table
called "items" and then subclass items, ie
class Todo < Item

This is also in the Agile book, and might be the best way of doing
things. Alternatively, make a method on the User class called
"top_ten" that grabs the top ten from each type of item (the most
you''ll ever need), rams them into an array, sort the array by
created_at desc, and then throw away all but the first ten.
Cumbersome, but it''ll work.

But yeah, I''d consider STI, before the cumbersome way.

Also: do consider cacheing. Slow queries might not be too much of a
burn if they''re only being made once every half hour, and then when
anything gets saved/altered...

Also, I should just add: I''m not that brilliant a developer, so other
people may be able to solve this problem better. But there''s LOTS in
those two chapters on ActiveRecord that might help you, so do reread
them.

On 10/05/06, Tom Armitage <tom.armitage@gmail.com>
wrote:
> > Tom, thats brilliant. I am just looking again at the Agile book trying
> > to get my head around the observers. It may take a while. (page 280
> > onwards).
> >
> > Tell me Tom, could this help with my other problem I have looming. I
> > have an overview page that is going to list each of the users projects
> > and underneath each project there will be a list of the latest 10
> > updated/created items. These items will be from one of 4 ActiveRecord
> > models (like messages, todos, tickets) I was trying to work oyt how to
> > query each project then find the top 10 for each of the has_maany
items,
> > then re iterate over the array of results ordering them in date order.
> > This would be for each project. Similar to basecamps dashboard (in
> > function anyway). This is the next hurdle! Would your suggestion here
> > help as well?
> >
>
> OK. So one thing to consider is Single Table Inheritance; if the
> "items" users are fairly similar, you could store them in a table
> called "items" and then subclass items, ie
> class Todo < Item
>
> This is also in the Agile book, and might be the best way of doing
> things. Alternatively, make a method on the User class called
> "top_ten" that grabs the top ten from each type of item (the most
> you''ll ever need), rams them into an array, sort the array by
> created_at desc, and then throw away all but the first ten.
> Cumbersome, but it''ll work.
>
> But yeah, I''d consider STI, before the cumbersome way.
>
> Also: do consider cacheing. Slow queries might not be too much of a
> burn if they''re only being made once every half hour, and then
when
> anything gets saved/altered...
>

Tom Armitage wrote:
> Also, I should just add: I''m not that brilliant a developer, so
other
> people may be able to solve this problem better. But there''s LOTS
in
> those two chapters on ActiveRecord that might help you, so do reread
> them.
I must admit i''m not really getting the observer thing yet,
i''m trying
it now but can''t seem to get what I want.

STI is out of the question for the items due to many differences and 
complexities of the model. I

''m supprised that nobody has explained how the 37sigs guys do the 
dashboard thing from an activerecord perspective. It would be most 
interesting to see how they have done it with a few examples. Its stuff 
like this that needs to be added to Rails Recipes, real world app stuff.

-- 
Posted via http://www.ruby-forum.com/.