render => partial not recognizing method in call

[akkdio]

Perhaps it is something basic as a beginner I am.  I have the following:

controllers:

main

editions

works

composers

main: 

class MainController < ApplicationController

  def welcome

    @composers = Composer.find(:all).sort_by {|c| [c.last_name, c.first_name]}

  end 

end

works - editions - composers all have normal scaffold generated methods(CRUD)

Models: - relavent info (hopefully) provided:

class Composer < ActiveRecord::Base

  attr_accessible :first_name, :last_name

  has_many :works, dependent: :destroy

  before_destroy :ensure_not_referenced_by_any_work

....

 def editions

    works.map {|work| work.editions}.flatten.uniq

    

  end

....

end

class Edition < ActiveRecord::Base

  

  validates :publisher_id, :description, :price, :year, presence: true

  has_many :environments

  has_many :works, through: :environments

  belongs_to :publisher

  has_many :orders

  

  attr_accessible :descripition, :price, :work_id, :year, :title, :publisher_id

....

end

class Work < ActiveRecord::Base

  attr_accessible :composer_id, :title

  belongs_to :composer

  has_many :environments

  has_many :editions, :through => :environments

  

  has_many :instruments, :through => :environments

...

end

class Environment < ActiveRecord::Base

    attr_accessible :instrument_id, :name, :work_id, :edition_id

    belongs_to :work

    belongs_to :instrument

    belongs_to :edition

end

I want the following partial to be shown in the Main#Welcome view:

partial is located in the composer view folder:

<h3>Editions List</h3>

<ul>

<% @composer.editions.map do |edition| %> #line 3 in error below

<li><%= link_to_edition_title(edition)%></li>

<% end %>

</ul>

The link_to_edition_title(edition)... may not be relavent but here it is in the edition helper module:

def link_to_edition_title(edition)

    link_to(edition.nice_title, edition_path(edition))

  end

My limited knowledge believes the call to the partial should work and indeed it does if done like this within the Composer#Show view:

<%= render "edition" %>

However, when I make the partial call from the Main#Welcome view like this:

The Main#Welcome view:

<%= render :partial => "composers/edition" %>

It results in this error:

NoMethodError in Main#welcome

Showing /Users/akkdio/railsapps/rails_3/ruby_for_rails/r4r_music/r4r_music1/app/views/composers/_edition.html.erb where line #3 raised:

undefined method `editions' for nil:NilClass

This is the first linke of the trace:

app/views/composers/_edition.html.erb:3:in `_app_views_composers__edition_html_erb__1574837102347920251_2165688820'

If more is needed please let me know.  Appreciate any nudge as to how I would change the partial or somehow get the editions method to be recognized in this call - the idea is to be able to share the partial across the application.  

Thanks for your help,

Andrew

[Colin Law]

On 12 June 2012 13:09, akkdio <akk...@gmail.com> wrote:
> Perhaps it is something basic as a beginner I am.  I have the following:

There was no need to show all this code, it is easier for us to see
what is going on if you just show the relevant bits

> [snip]

>
> I want the following partial to be shown in the Main#Welcome view:
>
> partial is located in the composer view folder:
>
> <h3>Editions List</h3>
> <ul>
> <% @composer.editions.map do |edition| %> #line 3 in error below

> [snip]

>
> My limited knowledge believes the call to the partial should work and indeed
> it does if done like this within the Composer#Show view:
>
> <%= render "edition" %>
>
> However, when I make the partial call from the Main#Welcome view like this:
> The Main#Welcome view:
> <%= render :partial => "composers/edition" %>
>
> It results in this error:
>
> NoMethodError in Main#welcome
>
> Showing
> /Users/akkdio/railsapps/rails_3/ruby_for_rails/r4r_music/r4r_music1/app/views/composers/_edition.html.erb
> where line #3 raised:
>
> undefined method `editions' for nil:NilClass

That means that @composer is nil, since that is the object on which
'editions' is being called.

Have a look at the Rails Guide on Layouts and Rendering, particularly
the section Using Partials to see how to pass local variables to the
partial.

Also have a look at the guide on debugging to get ideas on how to
debug your code so that you can work out what is going on.

I notice that you have asked for help twice before on this list and
neither time did you reply to the suggestions offered or report
whether you had found a solution. :(

Colin

[Max Reznichenko]

Hi, Andrew

The error says the @composer variable is not set. 

By the code I see, that you are setting @composers variable.

Take a look at the starting guide on rendering in Ruby on Rails as an approach itself is wrong.

Max

вторник, 12 июня 2012 г., 15:09:30 UTC+3 пользователь akkdio написал:

[akkdio]

> Perhaps it is something basic as a beginner I am.  I have the following:

There was no need to show all this code, it is easier for us to see
what is going on if you just show the relevant bits

Understand and thanks.  

Will check this. thanks.  

I notice that you have asked for help twice before on this list and
neither time did you reply to the suggestions offered or report
whether you had found a solution. :(

Not an excuse but I was not notified of the someone answering... Sorry.   This time I checked back and check "email updates to me" Sorry again - I appreciate all the guidance i can get.    

Colin

[akkdio]

My solution/learning (sort of) I read through the Rails Guide and it was somewhat helpful - lots to learn -  

My disconnect however that I was under the impression that the partial because it worked when I used in the composer show method it would work in the Main#Welcome view.  Well, this is incorrect because in the Composer#Index view I click on the Composer ID (set up as a link_to on the id:

 <td><%= link_to composer.id, composer_path(composer) %></td>

This is how the partial gets the composer id in order  make the editions partial work and why the editions method returned a Nil when called from the Main#welcome view.  It was saying " what composer?  I can't find no stinking Composer"   If I do want the editions listed in the Main#Welcome view for each composer then I will have to find a way to send the editions method the composer id it is looking for.   Time for more reading.

Thanks all for the nudge.