# Blocks in views **URL:** \ **Category:** Rails\ **Created:** [November 18, 2006, 8:42pm UTC](https://www.ruby-forum.com/t/blocks-in-views/76435 "2006-11-18T20:42:06Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![zerohalo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/5fc32e/32.png) [@zerohalo](https://www.ruby-forum.com/u/zerohalo)\ **Post date:** [November 18, 2006, 8:42pm UTC](https://www.ruby-forum.com/t/blocks-in-views/76435/1 "2006-11-18T20:42:06Z")
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? ---
**Author:** ![zerohalo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/5fc32e/32.png) [@zerohalo](https://www.ruby-forum.com/u/zerohalo)\ **Post date:** [November 18, 2006, 8:57pm UTC](https://www.ruby-forum.com/t/blocks-in-views/76435/2 "2006-11-18T20:57:22Z")
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 ---
**Author:** ![zerohalo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/5fc32e/32.png) [@zerohalo](https://www.ruby-forum.com/u/zerohalo)\ **Post date:** [November 18, 2006, 8:55pm UTC](https://www.ruby-forum.com/t/blocks-in-views/76435/3 "2006-11-18T20:55:22Z")
Hi – On Sat, 18 Nov 2006, zerohalo wrote: > \<% 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 | removed\_email\_address@domain.invalid Author of “Ruby for Rails” [1] | Ruby/Rails training & consultancy [3] DABlog (DAB’s Weblog) [2] | Co-director, Ruby Central, Inc. [4] [1] [Ruby for Rails](http://www.manning.com/black) | [3] [http://www.rubypowerandlight.com](http://www.rubypowerandlight.com) [2] [http://dablog.rubypal.com](http://dablog.rubypal.com) | [4] [http://www.rubycentral.org](http://www.rubycentral.org) ---
**Author:** ![zerohalo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/5fc32e/32.png) [@zerohalo](https://www.ruby-forum.com/u/zerohalo)\ **Post date:** [November 18, 2006, 9:01pm UTC](https://www.ruby-forum.com/t/blocks-in-views/76435/4 "2006-11-18T21:01:23Z")
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 P. wrote: > \<%= 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](http://www.nabble.com/-Rails--blocks-in-views-tf2661201.html#a7422902) Sent from the RubyOnRails Users mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![zerohalo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/5fc32e/32.png) [@zerohalo](https://www.ruby-forum.com/u/zerohalo)\ **Post date:** [November 18, 2006, 9:09pm UTC](https://www.ruby-forum.com/t/blocks-in-views/76435/5 "2006-11-18T21:09:23Z")
Hi – On Sat, 18 Nov 2006, Conrad T. wrote: > > > > | 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 | removed\_email\_address@domain.invalid Author of “Ruby for Rails” [1] | Ruby/Rails training & consultancy [3] DABlog (DAB’s Weblog) [2] | Co-director, Ruby Central, Inc. [4] [1] [Ruby for Rails](http://www.manning.com/black) | [3] [http://www.rubypowerandlight.com](http://www.rubypowerandlight.com) [2] [http://dablog.rubypal.com](http://dablog.rubypal.com) | [4] [http://www.rubycentral.org](http://www.rubycentral.org) ---
**Author:** ![zerohalo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/5fc32e/32.png) [@zerohalo](https://www.ruby-forum.com/u/zerohalo)\ **Post date:** [November 18, 2006, 9:15pm UTC](https://www.ruby-forum.com/t/blocks-in-views/76435/6 "2006-11-18T21:15:24Z")
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](http://www.nabble.com/-Rails--blocks-in-views-tf2661201.html#a7423050) Sent from the RubyOnRails Users mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![zerohalo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/5fc32e/32.png) [@zerohalo](https://www.ruby-forum.com/u/zerohalo)\ **Post date:** [November 18, 2006, 9:19pm UTC](https://www.ruby-forum.com/t/blocks-in-views/76435/7 "2006-11-18T21:19:25Z")
Hi – On Sat, 18 Nov 2006, s.ross wrote: > 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 | removed\_email\_address@domain.invalid Author of “Ruby for Rails” [1] | Ruby/Rails training & consultancy [3] DABlog (DAB’s Weblog) [2] | Co-director, Ruby Central, Inc. [4] [1] [Ruby for Rails](http://www.manning.com/black) | [3] [http://www.rubypowerandlight.com](http://www.rubypowerandlight.com) [2] [http://dablog.rubypal.com](http://dablog.rubypal.com) | [4] [http://www.rubycentral.org](http://www.rubycentral.org) ---
**Author:** ![zerohalo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/5fc32e/32.png) [@zerohalo](https://www.ruby-forum.com/u/zerohalo)\ **Post date:** [November 19, 2006, 5:36am UTC](https://www.ruby-forum.com/t/blocks-in-views/76435/8 "2006-11-19T05:36:05Z")
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. ---
**Author:** ![zerohalo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/5fc32e/32.png) [@zerohalo](https://www.ruby-forum.com/u/zerohalo)\ **Post date:** [November 18, 2006, 9:11pm UTC](https://www.ruby-forum.com/t/blocks-in-views/76435/9 "2006-11-18T21:11:24Z")
Hi – On Sat, 18 Nov 2006, s.ross wrote: > > \<% 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 | removed\_email\_address@domain.invalid Author of “Ruby for Rails” [1] | Ruby/Rails training & consultancy [3] DABlog (DAB’s Weblog) [2] | Co-director, Ruby Central, Inc. [4] [1] [Ruby for Rails](http://www.manning.com/black) | [3] [http://www.rubypowerandlight.com](http://www.rubypowerandlight.com) [2] [http://dablog.rubypal.com](http://dablog.rubypal.com) | [4] [http://www.rubycentral.org](http://www.rubycentral.org)