contentFor yields strange results when combined with asyncHelper

[halfdan]

We currently experience a weird issue with an asynchronous helper when it is used inside a contentFor. (TryGhost/Ghost#2127)

I wrote a small app that demonstrates the issue at: https://github.com/halfdan/hbs-weird

The output looks like the following:

Weird express-hbs behaviour

Unexpected behaviour: __CoHMbGlL__

Strangely not so weird

12

Instead of getting 12 as output for both usages of the {{weird}} helper the one used in the contentFor returns a hash of some kind. I managed to track it down to being the result of the following line: https://github.com/barc/express-hbs/blob/master/lib/hbs.js#L566 which seems to return the shown value as a string (changes for every request).

[mgutz]

That looks like the placeholder ID for the async helper, which replaced when the promise completes. I'll look tomorrow.

[halfdan]

It's also worth to note that the line at https://github.com/halfdan/hbs-weird/blob/master/views/index.hbs#L3 does not show up in the output.

[mgutz]

The missing line is due to {{{body}}} missing in the layout.

The problem was blocks in the layout were not checking for async results. Please checkout the branch issue-53 which should fix the issue. See the file test/issues.js for issue-53. If all is well, I will merge.

[halfdan]

@mgutz Seems to work perfectly! So I'm 👍 for the merge.

[halfdan]

@mgutz Unfortunately we discovered another related issue just a few minutes ago. When using an async helper inside a block and passing it as a parameter to another helper, the same issue still seems to appear.

TryGhost/Ghost#2155 (comment)

[mgutz]

Please update your example project or edit the test and I'll try fixing.