Mustache: DOM exception when applying certain block patterns

[bmomberger-reciprocity]

http://jsfiddle.net/B8kWR/1/

Similar to #241 but outside of attributes, when using can.Observes to live-bind, this pattern will cause an error in the escape case in can.Mustache.txt (adding a newly generated text node). This is on Chrome 24; other browsers have not been tested.

Workaround: for the case of "show a, or b if a does not exist" try these helpers from github/recipocity/grc:

/*
  Usage:  {{firstexist possibly_null possibly_null_as_well 'fallback' }}
              {{firstnonempty possibly_empty possibly_empty_as_well 'fallback' }}
*/
can.each(["firstexist", "firstnonempty"], function(fname) {
  Mustache.registerHelper(fname, function() {
    var args = can.makeArray(arguments).slice(0, arguments.length - 1);
    for(var i = 0; i < args.length; i++) {
      if(typeof v === "function") v = v.call(this);
      var v = args[i];
      if(v != null && (fname === "firstexist" || !!(v.toString().trim()))) return v;
    }
    return "";
  });
});

[pmccartney]

Is this referring to "NOT_FOUND_ERR: DOM Exception 8" ? I was about to post a bug about this. Here is what I have seen; Given a model with attr 'name' and a proto function isLoggedIn(), handing it to the following mustache file, this will cause the exception.

{{#isLoggedIn}}{{name}}{{/isLoggedIn}}

Can.js : line 5872

Same error in FF: "Not Found Error: Node was not found"

[bmomberger-reciprocity]

That is indeed the issue I am seeing. As far as I can tell, it's not a null-reference type of issue; it may be that we are causing CanJS to try to insert a text node in a parent while providing a positioning reference that is not a child of the parent. I have not yet investigated it further than this.

[jbmillini]

Ignore this comment. Apologies about the spam. Testing our community page.

[pmccartney]

This is actually a pretty major issue as you can't even do simple bound lists with mustache. Even #each doesn't work.
{{#users}}{{name}}{{/users}} or
{{#each users}}{{name}}{{/each}} fails

Who decides when this should be labeled a bug?

[daffl]

This is the same issue as #153 right?

[pmccartney]

Yes. Sorry, it is. At least for the cases I am running into.

[daffl]

Ok makes sense. Does the workaround mentioned there work for you for? We'll try our best making this fix a priority for Mustache in the 1.1.4 release.

[pmccartney]

Works great! All the work that has been put into this is incredible.

[bmomberger-reciprocity]

With 1.1.4, using an {{#if}} block no longer throws errors, but also does not display text. My comments in #241 seem to apply here as well.

updated fiddle for 1.1.4: http://jsfiddle.net/B8kWR/2/

[andykant]

This is fixed with the fixes for #153.

Updated fiddle with the fix copy+pasted: http://jsfiddle.net/B8kWR/8/
I modified the test templates slightly because {^if text} isn't a valid helper call (should be {#unless text} or {^text}).

[airhadoken]

Eep. I also used {{^if ...}} in the test for #292 (it passed, though). Would you mind boyscouting that if you are working near it?

https://github.com/bitovi/canjs/blob/master/view/mustache/test/mustache_test.js#L1342

Thanks.

[andykant]

It looks like that does work now. That must have been something that changed between the version of Mustache in that fiddle and latest.