This is more of an academic question, but I was wondering why the
following doesn''t work in a view:
<%= @items.each { |@item| render :partial => ''itemrow'' }
%>
Of course it can be done like this, which works:
<% for @item in @items %>
<%= render :partial => ''itemrow'' %>
<% end %>
But I was curious as to why the first method doesn''t work (at least it
doesn''t work for me). Is it not possible to use blocks in views?
--
Posted via http://www.ruby-forum.com/.
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Hi -- On Sat, 18 Nov 2006, zerohalo wrote:> > This is more of an academic question, but I was wondering why the > following doesn''t work in a view: > > <%= @items.each { |@item| render :partial => ''itemrow'' } %> > > Of course it can be done like this, which works: > > <% for @item in @items %> > <%= render :partial => ''itemrow'' %> > <% end %> > > But I was curious as to why the first method doesn''t work (at least it > doesn''t work for me). Is it not possible to use blocks in views?What''s happening is this: <%= ... %> interpolates the string representation of whatever "..." evaluates to. In this case, "..." is a call to @items.each. The each method returns its receiver. So, in effect, what you''re doing is: <%= @items.to_s %> If you do the "for @item" one, or this: <% @items each do |@item| %> <%= render :partial => "itemrow" %> <% end %> then you''re interpolating the string representation of the rendering of the partial, zero or more times in succession. You could also do: <%= @items.map {|@item| render :partial => "itemrow" } %> which would give you an array of all the rendered results. It''s a little less straightforward, though, and depends on representing an array as a string, which is an unnecessary extra step. Mainly I mention it to illustrate the principle at work, which the difference between each and map shows you. David -- David A. Black | dblack-0o/XNnkTkwhBDgjK7y7TUQ@public.gmane.org Author of "Ruby for Rails" [1] | Ruby/Rails training & consultancy [3] DABlog (DAB''s Weblog) [2] | Co-director, Ruby Central, Inc. [4] [1] http://www.manning.com/black | [3] http://www.rubypowerandlight.com [2] http://dablog.rubypal.com | [4] http://www.rubycentral.org --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
Hi, it should be | item | instead of | @item | Also, I would recommend reading the section of AWDWR on using partials to render collections. Peace, -Conrad On 11/18/06, zerohalo <rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote:> > This is more of an academic question, but I was wondering why the > following doesn''t work in a view: > > <%= @items.each { |@item| render :partial => ''itemrow'' } %> > > Of course it can be done like this, which works: > > <% for @item in @items %> > <%= render :partial => ''itemrow'' %> > <% end %> > > But I was curious as to why the first method doesn''t work (at least it > doesn''t work for me). Is it not possible to use blocks in views? > > > -- > 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 -~----------~----~----~----~------~----~------~--~---
What do you mean by "doesn''t work"? Error? No output? Only one line of output? In any case, what <%= %> does is evaluate the Ruby inside it and concatenate the results onto the erb stream. The block you have specified returns, I believe, not a concatenation of the partials, but rather the last partial evaluated. HTH Daan Poron wrote:> > > This is more of an academic question, but I was wondering why the > following doesn''t work in a view: > > <%= @items.each { |@item| render :partial => ''itemrow'' } %> > > Of course it can be done like this, which works: > > <% for @item in @items %> > <%= render :partial => ''itemrow'' %> > <% end %> > > But I was curious as to why the first method doesn''t work (at least it > doesn''t work for me). Is it not possible to use blocks in views? >-- View this message in context: http://www.nabble.com/-Rails--blocks-in-views-tf2661201.html#a7422902 Sent from the RubyOnRails Users mailing list archive at Nabble.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 -~----------~----~----~----~------~----~------~--~---
Hi -- On Sat, 18 Nov 2006, Conrad Taylor wrote:> > > On 11/18/06, zerohalo <rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote: >> >> This is more of an academic question, but I was wondering why the >> following doesn''t work in a view: >> >> <%= @items.each { |@item| render :partial => ''itemrow'' } %> >> >> Of course it can be done like this, which works: >> >> <% for @item in @items %> >> <%= render :partial => ''itemrow'' %> >> <% end %> >> >> But I was curious as to why the first method doesn''t work (at least it >> doesn''t work for me). Is it not possible to use blocks in views? >> > > Hi, it should be > > | item | instead of | @item |Actually you can use instance variables as block params. Try this in irb: [1,2,3].each {|@x| p @x } David -- David A. Black | dblack-0o/XNnkTkwhBDgjK7y7TUQ@public.gmane.org Author of "Ruby for Rails" [1] | Ruby/Rails training & consultancy [3] DABlog (DAB''s Weblog) [2] | Co-director, Ruby Central, Inc. [4] [1] http://www.manning.com/black | [3] http://www.rubypowerandlight.com [2] http://dablog.rubypal.com | [4] http://www.rubycentral.org --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
Hi -- On Sat, 18 Nov 2006, s.ross wrote:> Daan Poron wrote: >> >> >> This is more of an academic question, but I was wondering why the >> following doesn''t work in a view: >> >> <%= @items.each { |@item| render :partial => ''itemrow'' } %> >> >> Of course it can be done like this, which works: >> >> <% for @item in @items %> >> <%= render :partial => ''itemrow'' %> >> <% end %> >> >> But I was curious as to why the first method doesn''t work (at least it >> doesn''t work for me). Is it not possible to use blocks in views? >> > > What do you mean by "doesn''t work"? Error? No output? Only one line of > output?I think the output will be a single hash-mark for each item in @items, representing a shortened string representation.> In any case, what <%= %> does is evaluate the Ruby inside it and concatenate > the results onto the erb stream. The block you have specified returns, I > believe, not a concatenation of the partials, but rather the last partial > evaluated.Actually it returns the original array, @items. The results of the calls to render are discarded. David -- David A. Black | dblack-0o/XNnkTkwhBDgjK7y7TUQ@public.gmane.org Author of "Ruby for Rails" [1] | Ruby/Rails training & consultancy [3] DABlog (DAB''s Weblog) [2] | Co-director, Ruby Central, Inc. [4] [1] http://www.manning.com/black | [3] http://www.rubypowerandlight.com [2] http://dablog.rubypal.com | [4] http://www.rubycentral.org --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
You *can* -- the syntax is parseable -- but that''s not usually what you meant. If you needed an instance variable for a method call, I guess this would make sense, but it still seems strange and an unintentional use of legal syntax. dblack wrote:> > > Actually you can use instance variables as block params. Try this in > irb: > > [1,2,3].each {|@x| p @x } > >-- View this message in context: http://www.nabble.com/-Rails--blocks-in-views-tf2661201.html#a7423050 Sent from the RubyOnRails Users mailing list archive at Nabble.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 -~----------~----~----~----~------~----~------~--~---
Hi -- On Sat, 18 Nov 2006, s.ross wrote:> dblack wrote: >> >> >> Actually you can use instance variables as block params. Try this in >> irb: >> >> [1,2,3].each {|@x| p @x } > > You *can* -- the syntax is parseable -- but that''s not usually what you > meant. If you needed an instance variable for a method call, I guess this > would make sense, but it still seems strange and an unintentional use of > legal syntax.I''ve done it sometimes when I want to do something like: <% @items.each do |@item| %> <%= text_field "item[]", "name" %> <% end %> It could also come in handy with rendering a partial, as it could save you the trouble of doing a :locals thing. David -- David A. Black | dblack-0o/XNnkTkwhBDgjK7y7TUQ@public.gmane.org Author of "Ruby for Rails" [1] | Ruby/Rails training & consultancy [3] DABlog (DAB''s Weblog) [2] | Co-director, Ruby Central, Inc. [4] [1] http://www.manning.com/black | [3] http://www.rubypowerandlight.com [2] http://dablog.rubypal.com | [4] http://www.rubycentral.org --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
Thanks, David, for the explanation. I didn''t understand the difference between map and each. And you''re exactly right, the wrong output that I got with the block was simply the array @items -- the partial itself wasn''t output even once. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---