what am i doing?

rubyonrails-talk
1

this is my first application in RoR and am kind of stuck. part of my confusion is where/when to use the model, controller or view.

one of my tables is called gi_maps which is basically a hash:

select * from gi_maps;

id>name 1|Gi 2|No-Gi

another is called divisions which has gi_maps hash and others:

select * from divisions;

id>gi_map_id|rank_map_id|weight_group_map_id|age_group_map_id| created_at|updated _at 3|2|4|4|3|2008-09-05 21:28:32|2008-09-05 21:28:32 4|1|6|4|3|2008-09-05 21:29:01|2008-09-05 21:29:01

my default show "view" (divisions/show.html.erb) just displays the id's for each entry:

Gi or No-Gi Rank Weight group Age group 2 4 4 3 Show Edit Destroy 1 6 4 3 Show Edit Destroy

divisions/show.html.erb: . . <p>   <b>Gi or No-Gi:</b>   <%=h @division.gi_map_id %> </p> . . .

so all of this works fine... except for the fact that people like to see words instead of numbers :slight_smile: so what i've tried to do is use my model (models/division.rb) to "collect" the corresponding "name" value for a given hash id (ie. gi_map_id). but for some reason this isn't working and i can't think of any other way to do it except for placing it in the controller or view section. but i *think* this should be done at the model level.

here are the files and errors the way i'm doing it (i'll truncate the files for readability):

models/gi_map.rb:

class GiMap < ActiveRecord::Base   belongs_to :divison end

models/division.rb:

class Division < ActiveRecord::Base

  belongs_to :match

  def self.gi_map_name     GiMap.first(:conditions => ["id = ?", self.id]).name   end end

controllers/divisions_controller.rb: . .   def show     @division = Division.find(params[:id])

    respond_to do |format|       format.html # show.html.erb       format.xml { render :xml => @division }     end   end . .

views/divisons/show.html.rb: . . <p>   <b>Gi or No-Gi:</b>   <%=h @division.gi_map_name %> </p> . . .

and here is the error when trying to "show" one record:

NoMethodError in Divisions#show

Showing divisions/show.html.erb where line #3 raised:

undefined method `gi_map_name' for #<Division:0x478b9b0>

Extracted source (around line #3):

1: <p> 2: <b>Gi or No-Gi:</b> 3: <%=h @division.gi_map_name %> 4: </p> 5: 6: <p>

i hope this isn't a total noob question! but i've already written this application in php/mysql and am just rewriting in an effort to learn RoR. so any help or tips would be greatly appreciated.

thanks!

ron

2

Defining methods with the self prefix denotes a class method. You are calling the method on an instance object. Remove the self and you will be good to go.

3

this is my first application in RoR and am kind of stuck. part of my confusion is where/when to use the model, controller or view.

class Division < ActiveRecord::Base

belongs_to :match

def self.gi_map_name GiMap.first(:conditions => ["id = ?", self.id]).name end end

You've created a class method (that's what def self. does) whereas this should really be an instance method. Usually you'd handle this via some associations. GiMap should have has_one :division (and not belongs_to :division - that would indicate that the gi_maps table has a division_id column) and division should belongs_to :gi_map (and it does as required have a gi_map_id column).

Then you'd just write (I suspect that personally I wouldn't bother)

def gi_map_name   gi_map.name end

Fred

4

wow! i was pretty far off :slight_smile: thanks for the tips! i would like to know more about when/where and what the implications are for using the has_one, belongs_to, etc. keywords. any links that would help me better understand what the hell i'm doing ? :slight_smile:

btw... i DO get what you are saying... after changing the belongs_to and has_one... i can just do this in my view:

<p>   <b>Gi or No-Gi:</b>   <%=h @division.gi_map.name %> </p>

thanks again!

5