feat($compile): backport $doCheck #14656
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I think we need to get a better understanding of what |
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Yeah, I'd love to have one of the devs who worked on this part confirm or correct what I've found (@vicb?). Commented in angular/angular#7307 regarding the effect of ChangeDetectionStrategy. Especially because CDS doesn't exist in Angular 1, this still appears to be a good reflection of Angular 2. |
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From what I understand of The Angular1 equivalent would pretty much be if |
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@dcherman is that based on internal design knowledge? That behavior is what the docs suggest, but they're confirmed to be at least partly incorrect (#7307) and the angular 2 directives that implement ngDoCheck (e.g. ngFor) are built around ngDoCheck just being a hook into the digest cycle (i.e. nothing in angular itself consumes the result of ngDoCheck -- any actions that need to be taken as a result of detected changes need to be taken in ngDoCheck itself). Possibility that ngDoCheck is not finished though...? |
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@zbjornson Not at all; that point is just from both tinkering with ng2 / reading the docs and points that I picked up during ngConf earlier this month. It's entirely possible that the description is no longer accurate. |
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@petebacondarwin My PR to correct the ng2 |
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@petebacondarwin @zbjornson Is there any progress on this issue? This hook seems to be quite vital in attempts to get rid of $scope in components when using angular 1.5 providing the ability to deep watch object properties supplementing capabilities of the $onChanges hook. As @zbjornson updated angular 2 docs on doCheck, the suggested implementation seems to correspond to what the hook does in angular 2. Are there any constraints preventing this hook to be introduced? |
| @@ -300,6 +300,9 @@ | |||
| * `changesObj` is a hash whose keys are the names of the bound properties that have changed, and the values are an | |||
| * object of the form `{ currentValue, previousValue, isFirstChange() }`. Use this hook to trigger updates within a | |||
| * component such as cloning the bound value to prevent accidental mutation of the outer value. | |||
| * * `$doCheck()` - Called on each digest cycle. Provides an opportunity to detect and act on | |||
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Perhaps to make it even more clear?
Called on each turn of the digest loop
Backuport ngDoCheck from Angular 2.
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@petebacondarwin do those doc revisions read better now? Thanks for the review. |
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There were a couple of issues with the way this is implemented. |
Backuport ngDoCheck from Angular 2. Closes #14656
What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)
Feature
What is the current behavior? (You can also link to an open issue here)
If implemented, $doCheck will not be invoked
What is the new behavior (if this is a feature change)?
$doCheck will be invoked on every digest cycle.
Does this PR introduce a breaking change?
No
Please check if the PR fulfills these requirements
Other information:
This mirrors the current actual behavior of Angular 2:
$onChanges,$onInit,$doCheck.$doCheck,$onChanges,$doCheck.(See the live peekaboo demo from the docs to see the sequence.)
ngDoCheckin Angular 2 just seems to be a hook into the digest cycle that supplements, but does not replace/override, the default change detector. The Angular 2 docs are incorrect (issue):$onChangesis indeed called, and the code indoCheckdoes not override the default CD./cc @gkalpak