ruby could not come after coffeescript in .js.coffee for ajax response

Question

I am using Rails 3.1, it seems that I could not use Ruby script after a CoffeeScript statement in my create_error.js.coffee view file for the AJAX response.

If I do it like this it will work:

<% if @attached_image.errors.any? %>
  alert 'something is wrong'
<% end %>

but if it is like the following, with a <% %> after the CoffeeScript statement,

errors_block = '<div id="errors_block"></div>'
<% if @attached_image.errors.any? %>
  something..
<% end %>

I will alway get an exception of ActionView::Template::Error (Parse error on line 6: Unexpected 'INDENT') on the if line. I've tried several samples, everytime it happens when a ruby <% %> comes after a coffeescript statement.

Why is that?

mu is too short · Accepted Answer · 2012-02-04T18:18:15.970

6

Sounds like you're running into indentation issues in your post-ERB CoffeeScript. Given this:

errors_block = '<div id="errors_block"></div>'
<% if @attached_image.errors.any? %>
  something...
<% end %>

The output will look like this when the if condition is true:

errors_block = '<div id="errors_block"></div>'

  something...

and that indentation starts a new block that doesn't make sense in that context; hence the "Unexpected 'INDENT'" error from the CoffeeScript compiler. You can see this in action in this snippet on coffeescript.org.

CoffeeScript is very sensitive to indentation so mixing ERB and CoffeeScript like that isn't a good idea. You'd be better off putting @attached_image.errors into a CoffeeScript variable and then doing the logic in CoffeeScript, something more like this (untested code):

errors = <%= @attached_image.errors.to_a.to_json.html_safe %>
errors_block = '<div id="errors_block"></div>'
if errors.length > 0
  something...

The JSON version of the errors array should be valid CoffeeScript so errors will be a CoffeeScript array. The to_a is there in case errors returns nil, I'm not sure off the top of my head if errors.nil? is possible but a little extra paranoia never hurt anyone.

You could also do this:

errors_block = '<div id="errors_block"></div>'
<% if @attached_image.errors.any? %>
something..
<% end %>

but that's harder to read and you will forget. You're better off using ERB to generate CoffeeScript data and letting CoffeeScript handle the logic.

edited Feb 04 '12 at 18:18

answered Feb 02 '12 at 19:05

mu is too short

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Hi mu, I tried to use `error_msgs = <%= @attached_image.errors.to_a.to_json %>` but I get `ActionView::Template::Error (reserved word "var" on line 1)`. Is there anything I've done wrong again? – larryzhao Feb 04 '12 at 14:40
Try adding an `html_safe` to keep it from encoding the quotes, please see my update. – mu is too short Feb 04 '12 at 18:18
hi mu, if I add html_safe, the : or the [] and {} will be removed by html encode then the string is not a json string any more – larryzhao Feb 10 '12 at 03:02
but I am inspired by you and answered my own question. – larryzhao Feb 10 '12 at 03:06
@larryzhao: Just adding the `html_safe` should work (at least it works for me). – mu is too short Feb 10 '12 at 03:31
is short, it works, I am sorry I was making a mistake. This is the best solution. – larryzhao Feb 10 '12 at 03:37

score 0 · Answer 2 · answered Feb 02 '12 at 13:22

0

Your file should be called:

create_error.js.coffee.erb

So you could add ruby on it.

answered Feb 02 '12 at 13:22

Maurício Linhares

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I found this https://github.com/rails/coffee-rails/issues/13 yesterday which told me to use js.coffee(without the erb part), and it actually works quite fine with the ruby code part, is only the coffeescript processor won't pass if there's `<% %>` after one of the coffee statement. But it works the other way around, or in between. I will edit the question to make it more clear. – larryzhao Feb 02 '12 at 14:54

ruby could not come after coffeescript in .js.coffee for ajax response

2 Answers2