Template repeat if syntax?

[Arthur Evans]

Hi folks,

I'm curious about the use of template binding with the `repeat if` syntax. This is documented in the template binding library:

http://www.polymer-project.org/docs/polymer/template.html

<template repeat if="{{ conditionalValue }}">
  Repeat if and only if conditionalValue is truthy.
</template>

However, things work a bit differently inside a Polymer element, and I haven't been able to get this form to work. Does anyone know if `repeat if` works inside a Polymer element?

Thanks,
Arthur

[Scott Miles]

>> However, things work a bit differently inside a Polymer element

Can you spell this out? What have you tried?

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[Arthur Evans]

My apologies, apparently I just didn't try enough things... or RTFM. This works as expected:

        <ul>
          <template repeat="{{s in salutations}}"  if="{{ salutations.length }}">
            <li>{{s.what}}: <input type="text" value="{{s.who}}"></li>
          </template>
        </ul>

I tried  if="{{ true }}" at first. Then I checked the expressions doc and realized that "true/false" weren't listed as accepted literals. 

However, I also found that  if="{{ 1 }}" didn't evaluate as truthy, but if="{{ 1 == 1 }}" did. That seems like a hiccup in the expression library (but it might be just another gap in my understanding).

Having a separate variable, this.showSaluations and using if="{{showSalutations}}" also worked as expected. 

My other confusions apparently related to my not getting the scoping correct. Fixed that.

Thanks,
Arthur

[Erik Arvidsson]

Polymer Expressions supports true and false as well as numbers and strings.

https://github.com/Polymer/polymer-expressions/tree/master/third_party/esprima

So if `if="{{true}}"` is not working that is a bug.

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--
erik