nil values - option to default to exclude them? about rabl

[kimptoc]

Hi,

Thanks for the options, just trying them now.

On the first option with the lambda, "m" is the model object, right - but what if we are using it in the scenario of "object false"...

Tried this, but it always excludes the field now :(

node(:message, :if => lambda { |m| @message.nil? }) { @message }

With option 2, I am probably just doing it wrong.

My helper is this:

module RablHelper

  def node_if_present(name, &block)
    node(name, { :if => lambda { |m| m.send(name) } }, &block)
  end

end

And this in the view:

node_if_present(:message) { @message }

But get this error:

    undefined method `node' for #<#<Class:0x106837fa0>:0x1068354a8>
    Extracted source (around line #2):

    1: object false
    2: node(:request_id) { @request_id }
    3: node(:status) { @status }
    4: node_if_present(:message) { @message }
    Rails.root: /Users/kimptoc/Documents/ruby/ecom/ecom1

Application Trace | Framework Trace | Full Trace
/Users/kimptoc/.rvm/gems/ree-1.8.7-2011.03@p-ecom1-rails3-wsse/bundler/gems/rabl-7f97b7e60aee/lib/rabl/engine.rb:20:in `render'
/Users/kimptoc/.rvm/gems/ree-1.8.7-2011.03@p-ecom1-rails3-wsse/bundler/gems/rabl-7f97b7e60aee/lib/rabl/engine.rb:162:in `send'
/Users/kimptoc/.rvm/gems/ree-1.8.7-2011.03@p-ecom1-rails3-wsse/bundler/gems/rabl-7f97b7e60aee/lib/rabl/engine.rb:162:in `method_missing'
(eval):4:in `render'
app/views/ws/new_quote.rabl:2:in `_app_views_ws_new_quote_rabl___1547417618_2202114200_0'
actionpack (3.0.7) lib/action_view/template.rb:135:in `send'
actionpack (3.0.7) lib/action_view/template.rb:135:in `render'
activesupport (3.0.7) lib/active_support/notifications.rb:54:in `instrument'
actionpack (3.0.7) lib/action_view/template.rb:127:in `render'
actionpack (3.0.7) lib/action_view/render/rendering.rb:59:in `_render_template'
activesupport (3.0.7) lib/active_support/notifications.rb:52:in `instrument'
activesupport (3.0.7) lib/active_support/notifications/instrumenter.rb:21:in `instrument'

[nesquena]

Generally I like to include nil values so the key still exists consistently in the API but obviously it depends on the use case. The only way right now is using the if syntax to check. I could see wanting it globally but to me this seems more like a case by case setting...

node(:foo, :if => lambda { |m| m.foo }) { ... }

Keep in mind helpers work in rabl as well so you could add a shortcut in theory...a helper that returns a proc.

[nesquena]

I just realized helpers open up a whole slew of extensions you could build for instance, in a helper you could theoretically do:

# app/helpers/rabl_helper.rb
def node_unless_nil(name, &block)
  node(name, { :if => lambda { |m| m.send(name) } }, &block)
end

and then use that in your template:

node_unless_nil(:foo) { ... }

[nesquena]

It looks like you have the logic reversed, try:

node(:message, :unless => lambda { |m| @message.nil? }) { @message }

Note in your example you said to display the message only if the message is nil which doesn't make sense.

As for the second example, you would need to include the helper directly into the template, just for fun try:

include RablHelpers
node_if_present(:message) { @message }

or to include special helpers in every template:

RABL::Engine.send(:include, RablHelpers)

I would probably just go with the direct "if" approach for now.

[kimptoc]

Hi,

Just tried this - the first, inline option, works now - I had been using ".present?" and tried switching to ".nil?" to see if it made a difference... guess I gave up too quick :(

Still cant get the helper to work.

• if I use the Engine.send option, its not finding RABL:: ... - I tried at the end of initializer and directly in the controller.
• If I include it in the template, I get undefined method "include"

Dont suppose its a new feature that I need to update the gem for?

Thanks,
Chris

[nesquena]

Ok try this:

helper RablHelpers
node_if_present(:message) { @message }

and see if that works. I am aircoding these so it is likely my examples are just wrong in some cases. This one might work, let me know :)

[kimptoc]

Hi,

Getting closer - the helper is being loaded, but the call in the helper is failing :(

kimptoc/rabl_examples@8360ef2

Thanks, Chris.

[nesquena]

What about just:

node(:message) { @message } if @message

I am sure it is close with the helper, but I am not sure exactly what you are after for it to do, my version was more of an example. I am sure you could get it working, it just depends on what you want the method to do.

[kimptoc]

Thats simpler/clearer - nice. Thanks.

[oharsta]

I realise this thread is very old, but it was the first one popping up on my google search "rabl exclude nils" so for future reference: I have created a pull request for excluding nil values globally: #514