Validating a liquid template

[Randy Schmidt]

Hi, I'm allowing users to customize sms messages using liquid + a
defined set of variables. I'm adding validations to make sure there
aren't any typos. The first kind, that there aren't any parsing
errors, is simple because Liquid will raise an exception if they don't
close a tag correctly. However, I also want to validate that they used
a valid variable. It looks like liquid will happily replace undefined
variables with an empty string. I'm digging through the source code to
find a way but haven't yet.

Any suggestions?

Thank you!
--
Forge38 LLC
Randy Schmidt
ra...@forge38.com
http://forge38.com
267-334-6833

[Jon Crawford]

Hey Randy-

I've used this pretty successfully: http://github.com/bhauman/validates_proper_liquid_syntax

The syntax looks like this:

validates_proper_liquid_syntax :layout

I don't think it validates for variable names, but it definitely
validates for valid tag names. You might be able to hack it up a bit
to pass it a list of acceptable variable names. Something like...

validates_proper_liquid_syntax :layout, :variables =>
['foo','bar','bacon']

And for bonus points:

validates_proper_liquid_syntax :layout, :required_variables =>
['foo'], :optional_variables => ['bar','bacon']

Hope that helps!

!jon

[Randy Schmidt]

On Tue, Dec 1, 2009 at 9:24 AM, Jon Crawford <ma...@joncrawford.com> wrote:
> Hey Randy-
>
> I've used this pretty successfully: http://github.com/bhauman/validates_proper_liquid_syntax

Thanks Jon! That is similar to what I am doing now but wrapped in a
nice method :)

I'm looking for a way to make sure the person making the template
doesn't have any typos when they save it in the database. The way I
have it now it just inserts an empty string which means it won't fail
but will also read kind of funny.

I have thought of a couple things to try and will give them a shot. If
I come up with anything "new" I'll report back.

Thanks!

[pascal]

i'm new to liquid but this is what came to my mind:

In addition you could parse the template and see if it raises any
exceptions:

Liquid::Template.parse("{% for p in prods %} {{p.description}}")
Liquid::SyntaxError: for tag was never closed
from /opt/local/lib/ruby/gems/1.8/gems/liquid-2.0.0/lib/liquid/
block.rb:84:in `assert_missing_delimitation!'
Hard to generate a user friendly error message from this though...

Pascal

On Dec 1 2009, 5:21 pm, Randy Schmidt <m...@r38y.com> wrote:

[hiddenloop]

This is pretty much what the plugin does - i've been using it
successfully in a production site for sometime with no issues;

http://github.com/bhauman/validates_proper_liquid_syntax/blob/master/lib/validates_proper_liquid_syntax.rb

m