<div class='row'>
<%= form.field_container :name do %>
<%= form.label :name, raw('Name' + content_tag(:span, ' *', :class => 'required')) %>
<%= form.text_field :name, :class => 'fullwidth' %>
<%= form.error_message_on :name %>
<% end %>
</div>
Why is this producing the following error?
$ erb -x -T - test.erb | ruby -c
-:3: syntax error, unexpected ')'
...form.field_container :name do ).to_s); _erbout.concat "\n"
... ^
-:9: syntax error, unexpected $end, expecting ')'
If you look at the code outputted by erb -x -T - test.erb:
#coding:ASCII-8BIT
_erbout = ''; _erbout.concat "<div class='row'>\n "
; _erbout.concat(( form.field_container :name do ).to_s); _erbout.concat "\n"
; _erbout.concat " "; _erbout.concat(( form.label :name, raw('Name' + content_tag(:span, ' *', :class => 'required')) ).to_s); _erbout.concat "\n"
; _erbout.concat " "; _erbout.concat(( form.text_field :name, :class => 'fullwidth' ).to_s); _erbout.concat "\n"
; _erbout.concat " "; _erbout.concat(( form.error_message_on :name ).to_s); _erbout.concat "\n"
; _erbout.concat " "; end ; _erbout.concat "\n"
; _erbout.concat "</div>\n"
; _erbout.force_encoding(__ENCODING__)
You can see that on the third line, a do is followed by a ). Ruby is expecting a do…end block, but gets a closing parenthesis. That’s the immediate cause of the syntax error.
The reason for erb outtputting bad code is that you are using <%= when you should be using <%. Changing your code to this fixes the syntax error:
<div class='row'>
<% form.field_container :name do %>
<%= form.label :name, raw('Name' + content_tag(:span, ' *', :class => 'required')) %>
<%= form.text_field :name, :class => 'fullwidth' %>
<%= form.error_message_on :name %>
<% end %>
</div>
I can’t run this code to test if it outputs what it should after my change, but the code generated by erb looks like it will work:
#coding:ASCII-8BIT
_erbout = ''; _erbout.concat "<div class='row'>\n "
; form.field_container :name do ; _erbout.concat "\n"
; _erbout.concat " "; _erbout.concat(( form.label :name, raw('Name' + content_tag(:span, ' *', :class => 'required')) ).to_s); _erbout.concat "\n"
# more...
Since this solution apparently does break the output, I looked into what mu is too short suggested. I checked if Erubis, which Rails 3 uses by default, behaves differently from ERB. The code outputted by erubis -x -T - test.erb (with the original, unedited test.erb):
_buf = ''; _buf << '<div class=\'row\'>
'; _buf << ( form.field_container :name do ).to_s; _buf << '
'; _buf << ' '; _buf << ( form.label :name, raw('Name' + content_tag(:span, ' *', :class => 'required')) ).to_s; _buf << '
'; _buf << ' '; _buf << ( form.text_field :name, :class => 'fullwidth' ).to_s; _buf << '
'; _buf << ' '; _buf << ( form.error_message_on :name ).to_s; _buf << '
'; end
_buf << '</div>
';
_buf.to_s
Line three has the exact same problem, and erubis -x -T - test.erb | ruby -c outputs the same syntax error. So the differences between ERB and Erubis are probably not the problem.
I also tried syntax-checking this piece of code from the official Rails documentation:
<%= form_for(zone) do |f| %>
<p>
<b>Zone name</b><br />
<%= f.text_field :name %>
</p>
<p>
<%= f.submit %>
</p>
<% end %>
It gets the same syntax error. So it’s not that your ERB code is badly written; your code is very similar to that example.
At this point my best guess is that erb’s -x flag, which translates an ERB template into Ruby code instead of evaluating it directly, is flawed, and does not support some features it should. Though now that I think about it, I am having trouble imagining exactly what Ruby code should be outputted when you output the result of a block that itself outputs text should work. At what times should each of the outputs be written – the result first, or the block contents first?