known-variables and tags

[eval]

It seems that #'parser/known-variables does not handle variables in tags correctly:

user=> (selmer/known-variables "{% if {{var}} %}{{other-var}}{% endif %}")
#{:other-var :{{var}}}
;; expected:
;; #{:other-var :var}

[yogthos]

That does look like a bug. I won't have a chance to take a look in the near future, but a PR would be welcome.

[seancorfield]

Is that just an alternate syntax for {% if var %}{{other-var}}{% endif %} (which I assume works?) I don't think I've ever seen {{..}} used inside {% .. %} like that...

[seancorfield]

No, that {{var}} format doesn't work inside {% .. %}:

user=> (html/render "{% if {{var}} %}yes{% else %}no{% endif %}" {:var true})
"no"
user=> (html/render "{% if var %}yes{% else %}no{% endif %}" {:var true})
"yes"

[yogthos]

Ah yeah that's a good good point, nesting a var inside a condition this way isn't actually supported. I missed that bit. I think we can close this then.

[eval]

Sorry, my example was too simple. I meant to refer to the recently added capability to have vars in custom tags:

(selmer/add-tag!
        :ifendswith
        (fn [args context-map content]
          (let [args (map #(selmer/resolve-arg % context-map) args)]
            (if (str/ends-with? (first args) (second args))
              (-> content :ifendswith :content)
              (-> content :else :content))))
        :else :endifendswith)

(selmer/known-variables "{% ifendswith {{var}} \"foo\" %}{{var}} ends with foo!{% endifendswith %}")
;; #{:{{var}} :var}

[seancorfield]

This is still var-in-a-tag which isn't supported by Selmer itself. You're explicitly calling resolve-arg in your own case which does its own rendering internally to support {{var}} -- but Selmer itself doesn't know anything about that.

However:

user=> (selmer/known-variables "{% ifendswith var1 \"foo\" %}{{var2}} ends with foo!{% endifendswith %}")
#{:var1 :var2}

That seems inconsistent -- var1 isn't really a variable in any useful way: it has to be explicitly looked up.

But I think perhaps resolve-arg isn't really doing what it is supposed to here? @didibus would need to chime in. I think it should probably have used selmer.filter-parser/lookup-args under the hood which supports the @var syntax used in filters (and I've been using a form of that in my custom tags).

Even if you use s.f-p/l-a and {% if endswith @var \"foo\" %}, known-variables is going to produce :@var which seems wrong?

user=> (selmer/known-variables "{% ifendswith @var1 \"foo\" %}{{var2}} ends with foo!{% endifendswith %}")
#{:var2 :@var1}

[yogthos]

It does look like using lookup-args to get the value might do the trick here. Right now resolve-arg just checks for literal, but a case where it's a reference isn't handled.

[eval]

Thanks both - my initial need for this was to check whether all variables of a template are provided. But the custom-tag example, as I now understand, is not something you would use often.