Get all variables used in a template

[anitsirc]

Hi,

Is there a way of finding out all variables being used in a template, or at least the ones that it couldn't replace when rendering the template? Both, the ones used as {{ name }} and also the ones used in other tags {% if name == 'John' %}

Thanks :)

[fw42]

Not that I know of, no. Sorry :(

[pushrax]

You could add some hooks to the variable lookup function if you are ok with running a custom liquid version.

[dsignr]

Hi, is there a solution for this yet? I'd also like to find all variables used in a template. Thank you.

[fw42]

No solution, sorry. And nothing planned so far. But I'm open to look at suggestions.

[dsignr]

Somewhat hacky, but I put together this for my use case:

def get_variables(t)
      variables = []
      nodes = Liquid::Template.parse(t).root.nodelist
      nodes.each do |n|
        variables << n.name.name if n.is_a? Liquid::Variable
      end #End loop
      #Return
      variables.uniq
 end #End method

>> get_variables("{{friend}} is such a {{animal}}")
>> ["friend", "animal"]

Not even sure if this is ok. What do you think? :D

Edit: (You know what I did)

[pushrax]

Assuming you only care about top level variables that will work. You also need to check that n.name is a VariableLookup though, if you have something like {{ "foo" }} then it'll be a string.

[dsignr]

Wow, I didn't know that you could have variables like that. Thanks for the suggestion, thanks!

[hugopl]

If you export all your variables using Liquid::Drop, you can run your liquid template against mock liquid drop with same methods as the usual liquid drop, but registering what variables were used.

[JanStevens]

With #1025 being available in 4.0.2 this can now be achieved using the following code

Liquid::ParseTreeVisitor.for(Liquid::Template.parse(liquid_string).root).add_callback_for(Liquid::VariableLookup) do |node|
  [node.name, *node.lookups].join('.')
end.visit.flatten.compact

[viral810]

liquid_string = "Hi {{ email }}"

vars = Liquid::Template
.parse(liquid_string)
.root
.nodelist
.select { _1.is_a? Liquid::Variable }
.map(&:name)
.map(&:name)
.uniq

vars # => ["email"]

[fer9305]

With #1025 being available in 4.0.2 this can now be achieved using the following code

Liquid::ParseTreeVisitor.for(Liquid::Template.parse(liquid_string).root).add_callback_for(Liquid::VariableLookup) do |node|
  [node.name, *node.lookups].join('.')
end.visit.flatten.compact

what would be the best way to filter out variables from for loops? Currently if i run this for a template that includes a loop it retrieves the variable used to iterate over the collection, for example:

{% for order in orders %}
  {{ order.id }}
{% endfor %}

as a result I get orders and order.id

[marctorrelles]

@fer9305 I'm also interested in this. Did you find a way to filter them out?