Dynamic typeahead expression no longer works

[oliversalzburg]

http://plnkr.co/edit/W2ghwZQogQX25ZaJO5t7?p=preview

Throws: Error: Expected typeahead specification in form of "_modelValue_ (as _label_)? for _item_ in _collection_" but got "{{expression}}".

Worked fine with typeahead, no longer works with uib-typeahead.

[pkozlowski-opensource]

I don't think it is a use case that we ever intended to support. I would suspect that it is more to do with the Angular version change, but this is pure speculation.

In short: IMO this is won't fix - you shouldn't be using interpolation where we do expect an expression

[pkozlowski-opensource]

More importantly - we don't want to "observe" this attribute as it would have a negative perf implications

[Foxandxss]

I never thought of typeahead being used like that. I do agree with @pkozlowski-opensource in here.

Out of curiosity, using latest ui-bootstrap and the deprecated non-prefixed version. Does it work?

[oliversalzburg]

@Foxandxss It works perfectly fine when replacing uib-typeahead with typeahead. As in, the deprecated version works fine.

[Foxandxss]

Then it is a bug.

[pkozlowski-opensource]

@Foxandxss I don't think it is a bug and I still don't think we should "fix" it. It might used in the past but this was never intentional. If it worked it was "by chance", side effect of the existing implementation. As such it isn't part of the API we've intended to provide.

What I'm trying to say is that not every change in impl is a regression (otherwise bug fixes would be considered regressions as well!) and we shouldn't strive to support each and every exotic use case. I feel like we've got part of responsibility in providing and supporting sane APIs. And it is not like we are not covering particular use-cases here: we still observe parts of the expressions from the micro-syntax. I see no point in observing it twice

[oliversalzburg]

We're using the typeahead in another directive and allow the typeahead expression to be set on the parent directive. I thought that we way we implemented this was the right way to do it, since it seemed to work just fine. If this is considered exotic and wrong, I'd be happy to adjust our implementation to the correct way to do it.

Any pointers would be appreciated.

[pkozlowski-opensource]

@oliversalzburg if you are wrapping typeahead it is kind of extending it. Unfortunately there is no great story for extending directives in ng right now, but there are certain techniques that make it possible.

Without going too much into the details, I would suggest either decorating the typeahead directive or re-compiling your directive template. I know that this is more work as compared to what you've been doing right now....

[oliversalzburg]

@pkozlowski-opensource Knowing that there is no easy solution is already assuring that I'm not missing something :) Thanks

[Foxandxss]

I see where the problem relies. In the deprecated version, we are parsing the typeahead attribute in the postlink (where it gets interpolated) and in the prefixed one, we are doing it on the controller (where is not interpolated).

Personally, I would fix it, we are not meant to break the existing users on their way of updating to use prefixes. It is a mere single line of code.

The user could hack it together, but that is a pain.