RecordNotFound - I'm not understanding the


#1

Hello! I’m new to rails ad ActiveRecord, and have a very basic
problem.

I have a very basic rails app, which I want to contain computers, and
notes. Each computer has associated notes. I’m getting an error I’m
not fully understanding when I try to view a computer. The view
should include a listing of notes for the associated computer, but
instead, I get this:

Couldn’t find Note without an ID

The link that takes the user to the screen with the problem:
<%= link_to ‘Show’, :action => ‘show’, :id => computer %>

My controller:
def show
@computer = Computer.find(params[:id])
@notes = Note.find(params[:computer_id])
end

My view for show:
<% for column in Computer.content_columns %>

<%= column.human_name %>: <%=h @computer.send(column.name) %>

<% end %> <% for note in @notes %> <% for column in Note.content_columns %> <% end %> <% end %>
<%=h note.send(column.name) %>

<%= link_to ‘Edit’, :action => ‘edit’, :id => @computer %> |
<%= link_to ‘Back’, :action => ‘list_computers’ %>

I realize I’m not setting :computer_id anywhere, but using :id in my
controller for notes gives me the same issue, and I don’t want to pull
up notes with a particular id, but notes with a particular associated
computer. It seems like there should be a simple way to accomplish
this in rails, and I’m just missing it.

Thank you in advance!


#2

On Jun 4, 2007, at 2:29 PM, Big Dave S. wrote:

My controller:
def show
@computer = Computer.find(params[:id])
@notes = Note.find(params[:computer_id])
end

Presuming you have models along the lines of:

class Computer < ActiveRecord::Base
has_many :notes
end

class Note < ActiveRecord::Base
belongs_to :computer
end

What you probably want for the above is:

def show
@computer = Computer.find(params[:id], :include => :notes)
@notes = @computer.notes
end

Or if you wanted to search the notes without actually loading the
Computer, and params[:id] included the computer id, you’d want:

def show
@notes = Note.find_by_computer_id(params[:id])
end

If you haven’t read Agile Web D. With Ruby on Rails or one
of the other rails books, it’d definitely be worth your while to do
so, to get a better understanding of how rails handles parameters,
and associations.

James.


#3

Cheers,
Jodi
General Partner
The nNovation Group inc.
www.nnovation.ca/blog

On 4-Jun-07, at 2:29 PM, Big Dave S. wrote:

@notes = Note.find(params[:computer_id])

Hey Big Dave,

Note.find() is a finder that retrieves the row with the provided
primary key (so Note.find(1) will retrieve note with pk of 1).

To query all notes,

@notes = Note.find(:all, :conditions => [“computer_id = ?”, params
[:computer_id])

or better yet, since you’ve just retrieved the computer, then this
the way to go:

@notes = @computer.notes

sweet eh?

(as James suggested, pickup Pickaxe (er, ‘skateboard’). It’ll get you
over a bunch of early humps)

Jodi


#4

On Jun 4, 2007, at 2:43 PM, Jodi S. wrote:

small correction -

@notes = Note.find_by_computer_id(params[:id])

will return one row. Note.find_all_by_computer_id will do a find(:all)

Yeah, sorry – trying to get a response sent out quickly before
getting back to work.

James.


#5

On 4-Jun-07, at 2:38 PM, James S. wrote:

The link that takes the user to the screen with the problem:
class Computer < ActiveRecord::Base
@computer = Computer.find(params[:id], :include => :notes)
If you haven’t read Agile Web D. With Ruby on Rails or one
of the other rails books, it’d definitely be worth your while to do
so, to get a better understanding of how rails handles parameters,
and associations.

James.

small correction -

@notes = Note.find_by_computer_id(params[:id])

will return one row. Note.find_all_by_computer_id will do a find(:all

see my forthcoming announcement on find_by_associations to clean this
up even more

Jodi


#6

Big Dave S. wrote:

The link that takes the user to the screen with the problem:
<%= link_to ‘Show’, :action => ‘show’, :id => computer %>

I think you mean :id => @computer in the above line


Cheers,

  • Jacob A.