empty template are treated as not exist in templateCache

[oojerryoo]

Note: for support questions, please use one of these channels: https://github.com/angular/angular.js/blob/master/CONTRIBUTING.md#question. This repository's issues are reserved for feature requests and bug reports.

Do you want to request a feature or report a bug?

What is the current behavior?
empty template are treated as not exist in templateCache

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem via https://plnkr.co or similar (template: http://plnkr.co/edit/tpl:yBpEi4).
create a empty template, use template cache. and it is treated as not cached

What is the expected behavior?
should be treated as cached

What is the motivation / use case for changing the behavior?
i think this is a bug.

Which versions of Angular, and which browser / OS are affected by this issue? Did this work in previous versions of Angular? Please also test with the latest stable and snapshot (https://code.angularjs.org/snapshot/) versions.
multiple version include the latest

Other information (e.g. stacktraces, related issues, suggestions how to fix)
in $TemplateRequestProvider

this condition
if (!isString(tpl) || !$templateCache.get(tpl))

should be if (!isString(tpl) || !isUndefiend($templateCache.get(tpl)))

[Narretz]

What is the use case for adding an empty template to the cache?

[rjamet]

I've seen that pattern a few times when people have a ng-include in a template used in test, but want to disable it and don't request over the network while testing other stuff. If you have an empty TrustedResourceUrl whitelist, then the $sce call will throw. I advised them to refactor to $templateCache.put('key', 'placeholder') or so.

I'm not sure about the proposed fix though. The point of that check is to bypass security checks for templates in cache, but the proposed fix does the opposite. Adding a .has(key) in the caches, and keeping track of what has been set might be a better option.

[rjamet]

Turns out that cacheFactory.js returns early with no warning when given an undefined value: https://github.com/angular/angular.js/blob/master/src/ng/cacheFactory.js#L161

The commit (0e2ac3c) doesn't mention a particular reason, but this might be deliberate? @lgalfaso, maybe you remember? Oops, wrong, as pointed out below.

[gkalpak]

The commit you mention did not introduce the behavior you describe. It just fixed a "bug" where the value wasn't updated, but the entry was marked as "recently used". You need to look deeper 😛

But, why would you want to store an undefined value. That's what you get anyway, when calling get() with a key that is not stored in the cache.

[rjamet]

Oops... Deeper leads to the initial commit of cachefactory (497839f), so it's been that way forever, and seems like those valueless cache adds never did anything.

I'm also mixing stuff up: I was looking for the undefined templates behavior, which is fine, but the empty ("") template behavior is different, and there's a bug in templateRequest for that since it's defined but falsy. I'll write a PR.