class StoreController < ApplicationController
def index
@array = [1, 2, 3]
end
end
index.html.erb
-------------
render(:partial => "test", :object => @array)
_test.html.erb
------------
<% for num in test %>
<div><%= num %></div>
<% end %>
When I enter the url:
http://localhost:3000/store
in my browser, this is the output:
---------
NoMethodError in Store#index
Showing app/views/store/_test.html.erb where line #1 raised:
You have a nil object when you didn''t expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.each
Extracted source (around line #1):
1: <% for num in test %>
2: <div><%= num %></div>
3: <% end %>
-------------------------
The error is saying that test is nil. A ruby program:
array = [1, 2, 3]
for num in array
puts num
end
--output:--
1
2
3
My understanding was that when you write:
render(:partial => "test", :object => @array)
then inside the file _test.html.erb a local variable called test is
assigned the object @array. But in my application, @array is not
nil--it was assigned the array [1, 2, 3] in the controller. Why won''t
rails relent and loop through the array like I am commanding it to do?
--
Posted via http://www.ruby-forum.com/.
I figured it out. I wasn''t careful about where I was putting render(). I variously tried putting it in index.html.erb and in the layout (layouts/store.html.erb). I ended up with render() in both files: one specifying :object and one using :collection. !#$!@#$!@#$!@#$#!@@#$!!@#!!!! -- Posted via http://www.ruby-forum.com/.
views/store/index.html.erb: <%= render(:partial => "layouts/test", :object => @array) %> views/layouts/_test.html.erb: <% for num in test %> <div><%= num %></div> <% end %> On May 8, 5:59 pm, 7stud -- <rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote:> class StoreController < ApplicationController > def index > @array = [1, 2, 3] > end > > end > > index.html.erb > ------------- > render(:partial => "test", :object => @array) > > _test.html.erb > ------------ > <% for num in test %> > <div><%= num %></div> > <% end %> > > When I enter the url: > > http://localhost:3000/store > > in my browser, this is the output: > > --------- > NoMethodError in Store#index > > Showing app/views/store/_test.html.erb where line #1 raised: > > You have a nil object when you didn''t expect it! > You might have expected an instance of Array. > The error occurred while evaluating nil.each > > Extracted source (around line #1): > > 1: <% for num in test %> > 2: <div><%= num %></div> > 3: <% end %> > ------------------------- > > The error is saying that test is nil. A ruby program: > > array = [1, 2, 3] > > for num in array > puts num > end > > --output:-- > 1 > 2 > 3 > > My understanding was that when you write: > > render(:partial => "test", :object => @array) > > then inside the file _test.html.erb a local variable called test is > assigned the object @array. But in my application, @array is not > nil--it was assigned the array [1, 2, 3] in the controller. Why won''t > rails relent and loop through the array like I am commanding it to do? > -- > Posted viahttp://www.ruby-forum.com/.
Rick Lloyd wrote:> views/store/index.html.erb: > > <%= render(:partial => "layouts/test", :object => @array) %> > > views/layouts/_test.html.erb: > > <% for num in test %> > <div><%= num %></div> > <% end %>Sorry, I don''t know what that means, and I still can''t solve my original problem, which led to the test code in my op. Here is what I have now: class StoreController < ApplicationController def index @products = Product.find(:all) end def add_to_cart @cart = [1, 2, 3] end end layouts/store.html.erb ------------------- <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <meta http-equiv="content-type" content="text/html;charset=UTF-8" /> <title><% @page_title || "Store" %></title> <%= stylesheet_link_tag ''scaffold'', ''store2.css'' %> </head> <body> <div><%= render(:partial => "cart", :object => @cart) %></div> </body> </html> views/store/_cart.html.erb ----------------------- <% for num in cart -%> <div><%= num %></div> <% end %> When I go to http://localhost:3000/store in my browser, I get this: ------------- NoMethodError in Store#index Showing app/views/store/_cart.html.erb where line #1 raised: You have a nil object when you didn''t expect it! You might have expected an instance of Array. The error occurred while evaluating nil.each Extracted source (around line #1): 1: <% for num in cart -%> 2: <div><%= num %></div> 3: <% end %> Trace of template inclusion: app/views/layouts/store.html.erb ------------------ -- Posted via http://www.ruby-forum.com/.
To achieve this I use the syntax
<%= render :partial => ''cart'', :locals => {:mycart =
@cart} %>
Then use the variable mycart in the partial
Colin
2009/5/9 7stud --
<rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
>
> Rick Lloyd wrote:
> > views/store/index.html.erb:
> >
> > <%= render(:partial => "layouts/test", :object =>
@array) %>
> >
> > views/layouts/_test.html.erb:
> >
> > <% for num in test %>
> > <div><%= num %></div>
> > <% end %>
>
> Sorry, I don''t know what that means, and I still can''t
solve my
> original problem, which led to the test code in my op. Here is what I
> have now:
>
> class StoreController < ApplicationController
> def index
> @products = Product.find(:all)
> end
>
> def add_to_cart
> @cart = [1, 2, 3]
> end
> end
>
>
> layouts/store.html.erb
> -------------------
> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
>
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
>
> <html xmlns="http://www.w3.org/1999/xhtml"
xml:lang="en" lang="en">
> <head>
> <meta http-equiv="content-type"
content="text/html;charset=UTF-8" />
> <title><% @page_title || "Store" %></title>
> <%= stylesheet_link_tag ''scaffold'',
''store2.css'' %>
> </head>
> <body>
>
> <div><%= render(:partial => "cart", :object =>
@cart) %></div>
>
> </body>
> </html>
>
>
> views/store/_cart.html.erb
> -----------------------
> <% for num in cart -%>
> <div><%= num %></div>
> <% end %>
>
>
> When I go to http://localhost:3000/store in my browser, I get this:
> -------------
> NoMethodError in Store#index
>
> Showing app/views/store/_cart.html.erb where line #1 raised:
>
> You have a nil object when you didn''t expect it!
> You might have expected an instance of Array.
> The error occurred while evaluating nil.each
>
> Extracted source (around line #1):
>
> 1: <% for num in cart -%>
> 2: <div><%= num %></div>
> 3: <% end %>
>
> Trace of template inclusion: app/views/layouts/store.html.erb
> ------------------
>
> --
> Posted via http://www.ruby-forum.com/.
>
> >
>
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---
Colin Law wrote:> To achieve this I use the syntax > > <%= render :partial => ''cart'', :locals => {:mycart = @cart} %> >I think that is supposed to be: <%= render :partial => ''cart'', :locals => {:mycart => @cart} %>> Then use the variable mycart in the partial >and that produces the same error: ------------- NoMethodError in Store#index Showing app/views/store/_cart.html.erb where line #1 raised: You have a nil object when you didn''t expect it! You might have expected an instance of Array. The error occurred while evaluating nil.each Extracted source (around line #1): 1: <% for num in mycart -%> 2: <div><%= num %></div> 3: <% end %> Trace of template inclusion: app/views/layouts/store.html.erb RAILS_ROOT: /Users/autie/2testing/dir1/rails/store2 --------------- By the way, my file views/store/add_to_cart.html.erb is blank, although I don''t think that matters since the layout does not yield. -- Posted via http://www.ruby-forum.com/.
Tom Z Meinlschmidt
2009-May-09 10:34 UTC
Re: can''t get a simple partial to work !#$@#!$!!
hi, try this: 7stud -- wrote:> > <%= render :partial => ''cart'', :locals => {:mycart => @cart} %><%= render :partial => ''cart'', :collection => @cart %>>> Then use the variable mycart in the partialviews/store/_cart.html.erb ----------------------- <div><%= cart %></div> tom -- ==============================================================================Tomas Meinlschmidt, MS {MCT, MCP+I, MCSE, AER}, NetApp Filer/NetCache www.meinlschmidt.com www.maxwellrender.cz www.lightgems.cz ===============================================================================
2009/5/9 7stud -- <rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>> > Colin Law wrote: > > To achieve this I use the syntax > > > > <%= render :partial => ''cart'', :locals => {:mycart = @cart} %> > > > > I think that is supposed to be: > > <%= render :partial => ''cart'', :locals => {:mycart => @cart} %> >True, this (as corrected) works fine for me on rails 2.2.2. Which version are you using?> > > Then use the variable mycart in the partial > > > > and that produces the same error: > ------------- > NoMethodError in Store#index > > Showing app/views/store/_cart.html.erb where line #1 raised: > > You have a nil object when you didn''t expect it! > You might have expected an instance of Array. > The error occurred while evaluating nil.each > > Extracted source (around line #1): > > 1: <% for num in mycart -%> > 2: <div><%= num %></div> > 3: <% end %> > > Trace of template inclusion: app/views/layouts/store.html.erb > > RAILS_ROOT: /Users/autie/2testing/dir1/rails/store2 > --------------- > > By the way, my file views/store/add_to_cart.html.erb is blank, although > I don''t think that matters since the layout does not yield. > -- > Posted via http://www.ruby-forum.com/. > > > >--~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
On May 9, 6:47 am, 7stud -- <rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote:> Rick Lloyd wrote: > > views/store/index.html.erb: > > > <%= render(:partial => "layouts/test", :object => @array) %> > > > views/layouts/_test.html.erb: > > > <% for num in test %> > > <div><%= num %></div> > > <% end %> > > Sorry, I don''t know what that means, and I still can''t solve my > original problem, which led to the test code in my op. Here is what I > have now: > > class StoreController < ApplicationController > def index > @products = Product.find(:all) > end > > def add_to_cart > @cart = [1, 2, 3] > end > end >if you go to /store that''s just the index action so add_to_cart is never called and @cart is not set. Fred
Frederick Cheung wrote:> On May 9, 6:47�am, 7stud -- <rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote: >> >> � � @cart = [1, 2, 3] >> � end >> end >> > > if you go to /store that''s just the index actionYes. I realize that>> so add_to_cart is > never called and @cart is not set. >Ok, but if I go to /store/index why does the add_to_cart view ever come into play? @ variables in other actions are not set when /store/index executes, so why doesn''t rails throw errors when their views reference the @ variables set in their actions? -- Posted via http://www.ruby-forum.com/.
7stud -- wrote:> Frederick Cheung wrote: >> On May 9, 6:47�am, 7stud -- <rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote: >>> >>> � � @cart = [1, 2, 3] >>> � end >>> end >>> >> >> if you go to /store that''s just the index action > > Yes. I realize that> > >> so add_to_cart is >> never called and @cart is not set. >> > > > Ok, but if I go to /store/index why does the add_to_cart view ever come > into play? @ variables in other actions are not set when /store/index > executes, so why doesn''t rails throw errors when their views reference > the @ variables set in their actions?Ai yi yi. I''m putting the partial in the store *layout* so all the store views use it--including the index view. Thanks. -- Posted via http://www.ruby-forum.com/.
Maybe you should send the var through each page, you need to store it
and get it by method.
store it:
:locals => {:var = @a}
get it:
var = local_assigns[:var]
On May 10, 2:21 am, 7stud --
<rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:> 7stud -- wrote:
> > Frederick Cheung wrote:
> >> On May 9, 6:47 am, 7stud --
<rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote:
>
> >>> @cart = [1, 2, 3]
> >>> end
> >>> end
>
> >> if you go to /store that''s just the index action
>
> > Yes. I realize that>
>
> >> so add_to_cart is
> >> never called and @cart is not set.
>
> > Ok, but if I go to /store/index why does the add_to_cart view ever
come
> > into play? @ variables in other actions are not set when /store/index
> > executes, so why doesn''t rails throw errors when their views
reference
> > the @ variables set in their actions?
>
> Ai yi yi. I''m putting the partial in the store *layout* so all
the
> store views use it--including the index view.
>
> Thanks.
> --
> Posted viahttp://www.ruby-forum.com/.
When you render a partial you automagically get an object with the same name available in the partial For example, render :partial => ''foo'' passes the instance variable named @foo to the partial where I can then say: for f in @foo. In your first post you iterate over ''test'' but that variable isn''t created anywhere. Using: for a in @array might work providing that the partial is part of that controller though. Or rename @array to @test. I don''t know how many times I have stopped and looked for the painfully obvious - like with RESTful resources - the key is to make that part of the trouble shooting. On May 9, 1:47 am, 7stud -- <rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote:> Rick Lloyd wrote: > > views/store/index.html.erb: > > > <%= render(:partial => "layouts/test", :object => @array) %> > > > views/layouts/_test.html.erb: > > > <% for num in test %> > > <div><%= num %></div> > > <% end %> > > Sorry, I don''t know what that means, and I still can''t solve my > original problem, which led to the test code in my op. Here is what I > have now: > > class StoreController < ApplicationController > def index > @products = Product.find(:all) > end > > def add_to_cart > @cart = [1, 2, 3] > end > end > > layouts/store.html.erb > ------------------- > <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" > "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> > > <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> > <head> > <meta http-equiv="content-type" content="text/html;charset=UTF-8" /> > <title><% @page_title || "Store" %></title> > <%= stylesheet_link_tag ''scaffold'', ''store2.css'' %> > </head> > <body> > > <div><%= render(:partial => "cart", :object => @cart) %></div> > > </body> > </html> > > views/store/_cart.html.erb > ----------------------- > <% for num in cart -%> > <div><%= num %></div> > <% end %> > > When I go tohttp://localhost:3000/storein my browser, I get this: > ------------- > NoMethodError in Store#index > > Showing app/views/store/_cart.html.erb where line #1 raised: > > You have a nil object when you didn''t expect it! > You might have expected an instance of Array. > The error occurred while evaluating nil.each > > Extracted source (around line #1): > > 1: <% for num in cart -%> > 2: <div><%= num %></div> > 3: <% end %> > > Trace of template inclusion: app/views/layouts/store.html.erb > ------------------ > > -- > Posted viahttp://www.ruby-forum.com/.
AGoofin wrote:> When you render a partial you automagically get an object with the > same name available in the partial > > For example, render :partial => ''foo'' passes the instance variable > named @foo to the partial where I can then say: for f in @foo. >How do you know that @foo isn''t already available to all the views and that writing render(:partial => foo) doesn''t have any effect whatsoever on whether @foo is available in the partial?> In your first post you iterate over ''test'' but that variable isn''t > created anywhere. >Sure it is. Try it. I''m just a beginner but my Dave Heinemeier Hansson book says the variable test gets created by the render() statement, and my tests confirm that''s the way it works. More generally, when I write <% render(:partial => "random_name", :object => @var) %> and @var was assigned a value in the controller, then I find that the value of @var gets assigned to the variable "random name", and random_name can be accessed in the partial _random_name.html.erb. In addition, my tests show that @var can be accessed in _random_name.html.erb as well. I''m not sure why you would want to stuff the value of @var into another variable when you can just access @var directly. Switching the names seems confusing to me. -- Posted via http://www.ruby-forum.com/.
On May 10, 6:35 am, 7stud -- <rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote:> AGoofin wrote: > > Sure it is. Try it. I''m just a beginner but my Dave Heinemeier Hansson > book says the variable test gets created by the render() statement, and > my tests confirm that''s the way it works. More generally, when I write > > <% render(:partial => "random_name", :object => @var) %> > > and @var was assigned a value in the controller, then I find that the > value of @var gets assigned to the variable "random name", and > random_name can be accessed in the partial _random_name.html.erb. In > addition, my tests show that @var can be accessed in > _random_name.html.erb as well. I''m not sure why you would want to stuff > the value of @var into another variable when you can just access @var > directly. Switching the names seems confusing to me. >because depending on the state of local variables makes your partial more dependant on its environment. For example if the random_name partial always used @var you couldn''t use it to render a collection or if the thing that you wanted to render was @something.something_else. Personally I mostly equate this to ''why use method arguments when you could just use global variables?'' Fred
Perhaps you should look at the whole of DHH wrote. It is perhaps something like: render :partial => ''test'' or has a :test => @var clause to give the test variable. The code you posted doesn''t contain any variable named test, otherwise you wouldn''t get the error in the first place. If you want the code to work, replace ''test'' in the index view with ''@array'' On May 10, 1:35 am, 7stud -- <rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote:> AGoofin wrote: > > When you render a partial you automagically get an object with the > > same name available in the partial > > > For example, render :partial => ''foo'' passes the instance variable > > named @foo to the partial where I can then say: for f in @foo. > > How do you know that @foo isn''t already available to all the views and > that writing render(:partial => foo) doesn''t have any effect whatsoever > on whether @foo is available in the partial? > > > In your first post you iterate over ''test'' but that variable isn''t > > created anywhere. > > Sure it is. Try it. I''m just a beginner but my Dave Heinemeier Hansson > book says the variable test gets created by the render() statement, and > my tests confirm that''s the way it works. More generally, when I write > > <% render(:partial => "random_name", :object => @var) %> > > and @var was assigned a value in the controller, then I find that the > value of @var gets assigned to the variable "random name", and > random_name can be accessed in the partial _random_name.html.erb. In > addition, my tests show that @var can be accessed in > _random_name.html.erb as well. I''m not sure why you would want to stuff > the value of @var into another variable when you can just access @var > directly. Switching the names seems confusing to me. > > -- > Posted viahttp://www.ruby-forum.com/.
Frederick Cheung wrote:> On May 10, 6:35�am, 7stud -- <rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote: >> random_name can be accessed in the partial _random_name.html.erb. �In >> addition, my tests show that @var can be accessed in >> _random_name.html.erb as well. �I''m not sure why you would want to stuff >> the value of @var into another variable when you can just access @var >> directly. �Switching the names seems confusing to me. >> > > because depending on the state of local variables makes your partial > more dependant on its environment. For example if the random_name > partial always used @var you couldn''t use it to render a collection or > if the thing that you wanted to render was @something.something_else. > Personally I mostly equate this to ''why use method arguments when you > could just use global variables?'' >Ah. I see. AGoofin wrote:> Perhaps you should look at the whole of DHH wrote. It is perhaps > something like: render :partial => ''test'' or has a :test => @var > clause to give the test variable. >This is what he wrote: ---- The :object parameter to render takes an object that is assigned to a local variable with the same name as the partial. So, in the layout we could call this: <%= render(:partial => "cart", :object => @cart) %> and in the _cart.html.erb template, we can refer to the cart via the variable cart. p. 120, AWDWR(3rd) ------------- My tests show that the :partial name can be anything, e.g. "forrest_gump", and then inside the file _forrest_gump.html.erb, a variable named forrest_gump will be available and it will be assigned whatever value is specified for :object. In addition, my tests show that *all* the @variables that are set in the controller are available in the partial file no matter what I write in the render() statement. Therefore, a statement such as this:> For example, render :partial => ''foo'' passes the instance variable > named @foo to the partial where I can then say: for f in @foo.does not suddenly make @foo available in the partial. @foo is also available in the partial already. For instance, if I write: render :partial => "red" I can still access @foo in the file _red.html.erb.> The code you posted doesn''t contain any variable named test, otherwise > you wouldn''t get the error in the first place. >I explained why I got the error. It was because I ended up with two conflicting render statements, one in the layout and one in the index view: render(:partial => "some_name", :object => @var) render(:partial => "some_name", :collection => @var) Apparently, that confused rails. The error had nothing to do with the fact that ''test'' wasn''t previously defined somewhere in my code.> If you don''t want help - why post here? >Don''t get offended just because a beginner can''t confirm how you say rails works. I don''t blindly accept what someone says. I test things out to see how they work for myself. If my test results don''t confirm what I''ve been told, then I ask questions.> Variable names are special - they don''t just appear and have to be created.Is it so hard to believe that rails could create a variable when given a string, like here: partial => "forrest_gump" I can do it: class A end a = A.new str = "forrest_gump" val = [1, 2, 3] a.instance_variable_set("@#{str}", val) eval(" class << a attr_accessor :#{str} end") p a.forrest_gump --output:-- [1, 2, 3] I don''t know if things work differently in rails 2.3.2, which is what I am using. -- Posted via http://www.ruby-forum.com/.
7stud -- wrote: Corrections/clarification:> > I explained why I got the error. It was because I ended up with two > conflicting render statements, one in the layout and one in the index > view: > > render(:partial => "test", :object => @array) > render(:partial => "test", :collection => @array) > > Apparently, that confused rails. The error had nothing to do with the > fact that ''test'' wasn''t previously defined somewhere in my code. >-- Posted via http://www.ruby-forum.com/.