# Locals in render partials

**URL:** <https://www.ruby-forum.com/t/locals-in-render-partials/164617>\
**Category:** Rails\
**Created:** [April 3, 2009, 6:55am UTC](https://www.ruby-forum.com/t/locals-in-render-partials/164617 "2009-04-03T06:55:26Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![nike](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/dbc845/32.png) [@nike](https://www.ruby-forum.com/u/nike)\
**Post date:** [April 3, 2009, 6:55am UTC](https://www.ruby-forum.com/t/locals-in-render-partials/164617/1 "2009-04-03T06:55:26Z")

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In render partials can we pass arrays like this

a=[1,2,3]  
b=[5,6,7]  
c \<\< a \<\< b

render :partial=\>’’,:locals=\>{:c=\>c}

---

<div class="post-metadata">

**Author:** ![nike](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/dbc845/32.png) [@nike](https://www.ruby-forum.com/u/nike)\
**Post date:** [April 3, 2009, 2:14pm UTC](https://www.ruby-forum.com/t/locals-in-render-partials/164617/2 "2009-04-03T14:14:30Z")

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Nike M. wrote:

> In render partials can we pass arrays like this
> 
> a=[1,2,3]  
> b=[5,6,7]  
> c \<\< a \<\< b
> 
> render :partial=\>’’,:locals=\>{:c=\>c}

Yes. Write a functional test on the behavior of the page with the  
partial, and  
you should be able to detect the effects of :c inside there.

BTW, I always name variables passed in :locals like :@c, so they appear  
as @c  
inside. This makes them easier to test for nil, to mean “unassigned”.

(Do the latest versions of Rails and Ruby support that?)

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<div class="post-metadata">

**Author:** ![nike](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/dbc845/32.png) [@nike](https://www.ruby-forum.com/u/nike)\
**Post date:** [April 3, 2009, 2:35pm UTC](https://www.ruby-forum.com/t/locals-in-render-partials/164617/3 "2009-04-03T14:35:02Z")

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I tried your suggestion of passing locals as :@var on ruby 1.8.6 and  
rails 2.2.2 and it doesn’t seem to work

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<div class="post-metadata">

**Author:** ![nike](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/dbc845/32.png) [@nike](https://www.ruby-forum.com/u/nike)\
**Post date:** [April 3, 2009, 3:56pm UTC](https://www.ruby-forum.com/t/locals-in-render-partials/164617/4 "2009-04-03T15:56:25Z")

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Felix wrote:

> I tried your suggestion of passing locals as :@var on ruby 1.8.6 and  
> rails 2.2.2 and it doesn’t seem to work

Tx…

Not to hijack the thread (I’m unsure if Nike M.'s question feels  
answered  
yet), but we are having a major problem with…

- too many tests
- too many render :partial and render :inline calls
- too many @ variables magically passed without :locals

Apparently we reach a threshold where the magic stops working, and our  
most  
important @ variables disappear. This leads to a cascade of incorrect  
test  
failures on missing nils. (The infamous “whiny nil” takes over.)

So if I fix that using :locals =\>{ :@q =\> @q } in every render call,  
then I  
impair our project for upgrading to 2.2.2…

Elaborate sigh…

The problem with :locals =\> { :q =\> @q } is you can’t say ‘if q’ inside  
the  
partial to detect if the local is set. You can say ‘if @q’, because you  
rely on  
Ruby to provide a nil for decorated variables that don’t exist yet…

I seem to recall you can’t do ‘if defined? q’, either. Maybe.

This means the final recourse is too ugly for Rails: :locals =\>{ :things  
=\>{ :q  
=\> @q } }. Now the partial can use ‘if things[:q]’…

–  
Phlip