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default Pipes not on by default #3173
Description
In alpha 31, the default pipes are not on by default. In an application bootstrapped without any extra configuration, the following code:
{{'Hello World!' | uppercase}}
gets rendered as Hello World! instead of HELLO WORLD!. This is in a typescript setup, the problem can be reproduced like this:
- clone the angular2-seed
- npm install / gulp serve.dev
- add the code above on
home.html- the string does not get uppercased
Apparently the default pipes should be (as indicated here):
export const defaultPipes: Pipes = CONST_EXPR(new Pipes({
"iterableDiff": iterableDiff,
"keyValDiff": keyValDiff,
"async": async,
"uppercase": uppercase,
"lowercase": lowercase,
"json": json,
"limitTo": limitTo,
"number": decimal,
"percent": percent,
"currency": currency,
"date": date
}));
Activity
jessegood commentedon Jul 21, 2015
@jhades: I noticed that the uppercase and lowercase pipes work by adding
changeDetection:ON_PUSHin your@Component.However, it should still work with the default I believe.
fix(lowercase,uppercase): make stateless pipes
PatrickJS commentedon Jul 22, 2015
@jhades @jessegood this was my fault sorry about that. I pushed up a PR with the correct fix #3189. The problem was that I was doing more work than I should by only transforming on reference change. This is why
changeDetection: ON_PUSHwould allow it to work since you're providing a new reference to the bindings which would correctly transform the valuegkalpak commentedon Aug 3, 2015
FWIW, I don't think the issue was checking against the last input value, but the fact that in case of a match you would return the input value (not the transformed output).
Since these transforms are very cheap anyway, it's not worth having such an optimization in place anyway.
PatrickJS commentedon Aug 3, 2015
The problem was that I used
ObservablePipeas code reference since it was the only real pipe at the time (and of course we have no real docs at the time). Then there was also an API changed to remove having to returnNO_CHANGEreference when the transformation didn't need to happen (now changed to useWrappedValue). I was also doing smoke tests for these pipes in an app that optimized the change detection for reference checks (changeDetection: ON_PUSH) and the old pipe API.change_detection/pipes/observable_pipe.ts
ObservablePipehas to maintain reference of the Observable and has essentially 4 states in which the transform does something different that causes side effects: Observable without a subscription, Observable with a subscription, current value/returned value are the same, and current value/returned value are different. I only know this because I had to create anObservablePipethat prevented a cycle from happening when a change returns a new Observable reference. So there's actually a potential bug where the first state should return the returned value and the returned value should be dereferenced during the onDestroy Pipe lifecycle rather than the Observable reference lifecycle. With all that said I should have went back to refactor the pipes so that's my badgkalpak commentedon Aug 3, 2015
Looking at the commit that closed this issue (4dc6d74), I thought it was the fact that the untransformed value was returned after the initial invokation.
But I don't know much about pipes, so I probably misread that 😞
Sorry for the noise 😈
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