Unable to call .length on a List

[sethladd]

Hi,

I'm trying to do this:

Data model:

class Foo {
  List<String> things = ['one', 'two'];
}

Template:

{{#foo.things.length}}
{{#foo.things}}
<ul>
  <li>{{}}</li>
</ul>
{{/foo.things}}
{{/foo.things.length}}

In other words, I'd like to check the length of a list to see if there's anything there, so I can render <ul>

The exception is:

Unhandled exception:
Closure call with mismatched arguments: function '_getMustachContext'

NoSuchMethodError: method not found: '_getMustachContext'
Receiver: Instance of '_IterableMustacheContextDecorator'
Arguments: ["length"]
#0      Object.noSuchMethod (dart:core-patch/object_patch.dart:45)
#1      _MustacheContext._getContextForKey (package:mustache4dart/mustache_context.dart:75:37)
#2      _MustacheContext._getInThisOrParent (package:mustache4dart/mustache_context.dart:56:35)

Perhaps IterableMustacheContextDectorator is just dealing with iterables and not lists ?

[sethladd]

Thanks for taking a look!

[valotas]

From the mustache specs:

  - name: Empty List
    desc: Empty lists should behave like falsey values.
    data: { list: [ ] }
    template: '"{{#list}}Yay lists!{{/list}}"'
    expected: '""'

That said, the following should be sufficient:

{{#foo.things}}
<ul>
  <li>{{}}</li>
</ul>
{{/foo.things}}

[valotas]

Is the codebase you are working on open? Maybe I can have a look at the mustache part.

[sethladd]

I'll try that, thanks. I thought <ul> would be repeated for each element in things ?

Our new dartdoc uses mustache4dart: https://github.com/dart-lang/dartdoc

[valotas]

Yes you are right. But your code does the same too. I'll have a closer look tomorrow.

[sethladd]

The spec says what to do when you encounter an empty list: "do nothing" aka "kinda falsey". However, the inverse is not true. A non-empty list isn't truthy, it's for iteration.

Thanks for taking a look!

[sethladd]

Hi! Can we reopen this issue? It's marked as "wontfix".

Thanks!

[valotas]

I had a look at it. with 1.0.10 you should be able to do

{{^list.empty}}
<ul>
{{#list}}<li>{{.}}</li>{{/list}}
</ul>
{{/list.empty}}

I would like to avoid using the length. Is there any particular reason for using it?

[sethladd]

Thanks! Can you push to pub? I'd love to start using this.

[valotas]

It looks like this got off my radar. I'll publish a new version today night.

[sethladd]

Thank you!

On Sun, Mar 15, 2015, 6:55 AM Georgios Valotasios notifications@github.com
wrote:

It looks like this got off my radar. I'll publish a new version today
night.

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