An `EventEmitter` is a construct owned by Angular that should be
used for outputs as of right now.
As we are introducing the new `OutputRef` interface for the new output
function APIs, we also think `EventEmitter` should implement
`OutputRef`— ensuring all "known" outputs follow the same contract.
This commit ensures `EventEmitter` implements an `OutputRef`
Note: An output ref captures the destroy ref from the current injection
context for clean-up purposes. This is also done for `EventEmitter` in a
backwards compatible way:
- not requiring an injection context. EventEmitter may be used
elsewhere.
- not cleaning up subscriptions/completing the emitter when the
directive/component is destroyed. This would be a change in behavior.
Note 2: The dependency on `DestroyRef` causes it to be retained in all
bundling examples because ironically `NgZone` uses `EventEmitter`- not
for outputs. The code is pretty minimal though, so that should be
acceptable.
`EventEmitter` will now always retain `NgZone. This increases the
payload size slightly around 800b for AIO. Note that the other increases
were coming from previous changes. This commit just pushed it over the
threshold.
PR Close#54650
A model signal is technically an output, at runtime and conceptually.
This commit re-uses the shared output ref logic and ensures the
interfaces match.
PR Close#54650
This commit exposes the new `output()` API with numerous benefits:
- Symmetrical API to `input()`, `model()` etc.
- Fixed types for `EventEmitter.emit`— current `emit` method of
`EventEmitter` is broken and accepts `undefined` via `emit(value?: T)`
- Removal of RxJS specific concepts from outputs. error channels,
completion channels etc. We now have a simple consistent
interface.
- Automatic clean-up of subscribers upon directive/component destory-
when subscribed programmatically.
```ts
@Directive({..})
export class MyDir {
nameChange = output<string>(); // OutputEmitterRef<string>
onClick = output(); // OutputEmitterRef<void>
}
```
Note: RxJS custom observable cases will be handled in future commits via
explicit helpers from the interop.
PR Close#54650
This commit updates TestBed logic to take into account situations when dependencies loaded within `@defer` blocks may import NgModules with providers. For such components, we invoke provider override function, which recursively inspects and applies the necessary changes.
PR Close#54667
In zone-full applications, this is already true because effects are
scheduled inside a microtask and tracked by ZoneJS. When not using
zones, this should stay consistent on principle and for testability
reasons. A general pattern with zoneless testing will be to update state
and `await` some promise (i.e. `fixture.whenStable`, which will be
linked to `ApplicationRef.isStable`).
PR Close#53835
The current behavior of `autoDetect` in `ComponentFixture` does not
match production very well. It has several flaws that make it an
insufficient change detection mechanism:
* It runs change detection for the component under test _after_ views
attached to the `ApplicationRef`. This can cause real behavior
differences that break in production, because tests can observe view
refreshes in the incorrect order (for example, a dialog refreshing
before the component which opened it).
* Because of the above ordering, render hooks registered during change
detection of the fixture views _will not execute at all_ because
`ApplicationRef.tick` already happen.
* It does not rerun change detection on the view tree if there are more
dirty views to refresh after the render hooks complete.
* It effectively hides/swallows errors from change detection inside the
`onMicrotaskEmpty` subscription by not reporting them to the error
handler. Instead, this error ends up being unhandled in the
subscription and rxjs throws these in a `setTimeout`.
All of the above are problematic but this commit _does not_ fix the
final point. Ideally, we can land this in a future change but this
requires additional internal fixes. In the meantime, we have to juggle
special-case handling of the component fixture views within
`ApplicationRef.tick` using some special events to retain current
behavior and avoid errors from the fixture propagating to the `ErrorHandler`.
breaking note for future when isG3 flag condition is removed for v18:
The `ComponentFixture.autoDetect` feature now executes
change detection for the fixture within `ApplicationRef.tick`. This more
closely matches the behavior of how a component would refresh in
production. The order of component refresh in tests may be slightly
affected as a result, especially when dealing with additional components
attached to the application, such as dialogs. Tests sensitive to this
type of change (such as screenshot tests) may need to be updated.
PR Close#54354
One downside of implicit dependency tracking in `effect()`s is that it's easy
to for downstream code to end up running inside the effect context by accident.
For example, if an effect raises an event (e.g. by `next()`ing a `Subject`), the
subscribers to that `Observable` will run inside the effect's reactive context,
and any signals read within the subscriber will end up as dependencies of the
effect. This is why the `untracked` function is useful, to run certain
operations without incidental signal reads ending up tracked.
However, knowing when this is necessary is non-trivial. For example, injecting
a dependency might cause it to be instantiated, which would run the constructor
in the effect context unless the injection operation is untracked.
Therefore, Angular will automatically drop the reactive context within a number
of framework APIs. This commit addresses these use cases:
* creating and destroying views
* creating and destroying DI injectors
* injecting dependencies
* emitting outputs
Fixes#54548
There are likely other APIs which would benefit from this approach, but this
is a start.
PR Close#54614
Angular has the `@Attribute` decorator that allows for attributes to be injected from the host node, but we don't have an equivalent for the `inject` function. These changes introduce the new `HostAttributeToken` class that can be used to inject attributes similarly to `@Attribute`. It can be used as follows:
```typescript
import {HostAttributeToken, inject} from '@angular/core';
class MyDir {
someAttr = inject(new HostAttributeToken('some-attr'));
}
```
The new API works similarly to `@Attribute` with one key exception: it will throw a DI error when the attribute doesn't exist, instead of returning `null` like `@Attribute`. We made this change to align its behavior closer to other injection tokens.
PR Close#54604
This commit ensures that any internal render hooks that cause views to
become dirty again first refresh those dirty views before running user
render hooks. This ensures that user render hooks have the most complete
render state possible and stops them from needlessly executing multiple
times. This is important to maintain the goal of the public render
hooks, which is to provide the safest place to place code that depends
on DOM state, especially in ways that may force a browser paint.
PR Close#54224
Fixes that initializer functions weren't being recognized if they are aliased (e.g. `import {model as alias} from '@angular/core';`).
To do this efficiently, I had to introduce the `ImportedSymbolsTracker` which scans the top-level imports of a file and allows them to be checked quickly, without having to go through the type checker. It will be useful in the future when verifying that that initializer APIs aren't used in unexpected places.
I've also introduced tests specifically for the `tryParseInitializerApiMember` function so that we can test it in isolation instead of going through the various functions that call into it.
PR Close#54609
Currently, when a `@defer` block contains standalone components that import NgModules with providers, those providers are not available to components declared within the same NgModule. The problem is that the standalone injector is not created for the host component (that hosts this `@defer` block), since dependencies become defer-loaded, thus no information is available at host component creation time.
This commit updates the logic to collect all providers from all NgModules used as a dependency for standalone components used within a `@defer` block. When an instance of a defer block is created, a new environment injector instance with those providers is created.
Resolves#52876.
PR Close#52881
Fixes that initializer functions weren't being recognized if they are aliased (e.g. `import {model as alias} from '@angular/core';`).
To do this efficiently, I had to introduce the `ImportedSymbolsTracker` which scans the top-level imports of a file and allows them to be checked quickly, without having to go through the type checker. It will be useful in the future when verifying that that initializer APIs aren't used in unexpected places.
I've also introduced tests specifically for the `tryParseInitializerApiMember` function so that we can test it in isolation instead of going through the various functions that call into it.
PR Close#54480
Template pipeline is now the default template compiler.
A pair of source map tests is failing, related to DI in JIT mode; I will fix and re-enable these during the preview period.
PR Close#54571
ApplicationRef.tick has a loop that will refresh views again that have
an updated signal. This change ensures views marked with the `Dirty`
flag are also considered in this loop, but only inside g3 for now
because this may be considered a breaking change and we need to wait for
v18 to land externally.
PR Close#54572
Prior to this fix an incorrect view instance (a dynamically created component
one instead of the root view) was passed to the content query function. Having
incorrect view instance meant that a component instance could not be found.
This is a pre-existing bug, introduction of signal-based queries just surfaced it.
Fixes#54450
PR Close#54457
Getting the typing for `ɵunwrapWritableSignal` just right was tricky so these changes add some tests to ensure that we don't regress.
Also reworks the type tester a bit to make it easier to find where to add new test files.
PR Close#54387
Assure that the same readonly array corresponding to the children query results
is returned for cases where a query is marked as dirty but there were no actual
changes to the content of the results array (this can happen if a view is added
and removed thus marking queries as dirty but not influencing final results).
Fixes#54376
PR Close#54392
The newly introduced signal queries would error if no match exists, due to an
invalid read within the query internals.
This commit addresses the crash by allowing there to be no matches.
PR Close#54353
This updates some tests to use the public imports from `@angular/core` now that they are available,
and cleans up useless imports and inaccurate names.
PR Close#54334
In some situations, calling `markForCheck` can result in an infinite
loop in seemingly valid scenarios. When a transplanted view is inserted
before its declaration, it gets refreshed in the retry loop of
`detectChanges`. At this point, the `Dirty` flag has been cleared from
all parents. Calling `markForCheck` marks the insertion tree up to the
root `Dirty`. If the declaration is checked again as a result (i.e.
because it has default change detection) and is reachable because its
parent was marked `Dirty`, this can cause an infinite loop. The
declaration is refreshed again, so the insertion is marked for refresh
(again). We enter an infinite loop if the insertion tree always calls
`markForCheck` for some reason (i.e. `{{createReplayObservable() | async}}`).
While the case above does fall into an infinite loop, it also truly is a
problem in the application. While it's not an infinite synchronous loop,
the declaration and insertion are infinitely dirty and will be refreshed
on every change detection round.
Usually `markForCheck` does not have this problem because the `Dirty`
flag is not cleared until the very end of change detection. However, if
the view did not already have the `Dirty` flag set, it is never cleared
because we never entered view refresh. One solution to this problem
could be to clear the `Dirty` flag even after skipping view refresh but
traversing to children.
PR Close#54329
Fixes that `ɵunwrapWritableSignal` inferring getter functions as not matching the interface of `WritableSignal` instead of preserving them.
PR Close#54252
In a previous commit the TCB was changed to cast the assignment to an input in order to widen its type to allow `WritableSignal`. This ended up breaking existing inputs whose setter has a wider type than its getter. These changes switch to unwrapping the value on the binding side.
PR Close#54252
Reworks the TCB for two-way bindings to make them simpler and to avoid regressions for two-way bindings to generic inputs. The new TCB looks as follows:
```
var _t1: Dir;
var _t2 = _t1.input;
(_t1 as typeof _t2 | WritableSignal<typeof _t2>) = expression;
```
PR Close#54252
Adds support for model inputs in the framework. `model()` returns a writable signal that implicitly defines a input/output pair that can be used either in two-way bindings to keep two values in sync or by binding individually to the input and output. When the value of the `model` changes, it will emit an event with the current value.
Furthermore, these changes expand two-way bindings to accept `WritableSignal`. This will make it easier to transition existing code to signals in a backwards-compatible way.
Example:
```ts
@Directive({
selector: 'counter',
standalone: true,
host: {
'(click)': 'increment()',
}
})
export class Counter {
value = model(0);
increment(): void {
this.value.update(current => current + 1);
}
}
@Component({
template: `<counter [(value)]="count"/> The current count is: {{count()}}`,
})
class App {
count = signal(0);
}
```
PR Close#54252
This commit adds a JIT transform for signal-based queries, so that
queries are working as expected in JIT environments like `ng test` where
decorator metadata is needed as a prerequisite for the component
definition creation.
This is similar to the JIT transforms for signal inputs etc.
PR Close#54257
The compileNgModuleFactory dont need to be in the application_ref file (in fact
the whole logic has little to do with ApplicationRef and it is not even called
from the application_ref). Performing this move to avoid circular dependencies
when the new query as signals authoring functions are exported.
PR Close#54103
This commit changes the approach to the reactive node representing query
results: instead of creating a custom node type we can use a computed -
the main change to get there is representing dirty change notification as
a signal (a counter updated every time a query changes its dirty status).
This change is dictated by simplification (we can avoid creation of a custom
signal type) as well as fixes to the multiple issues not covered by the
initial implementation:
- assuring referential stability of results (ex.: the same array instance
returned from child queries until results change);
- per-view results collection to avoid a situation where accessing query
results during view creation would return partial / inconsistent results;
- proper refresh of query results for both live and non-connected consumers.
All the above cases are covered by the additional tests in this commit.
PR Close#54103
This commit adds tests for content queries and fixes the arguments
order in the contentQuerySignal instruction, thus fixing a bug
discovered while adding tests.
PR Close#54103
This commits converts the hand-written tests into their usual,
compiled form. We can perform this change now since the compiler
bits of the queries-as-signal story landed.
PR Close#54103
Updates the acceptance authoring test compiler targets to support
multiple spec files. This will be useful for output, model, inputs
and queries.
PR Close#54253
This commit introduces the `output()` function and corresponding
runtime code.
In practice, `output()` will defer to `EventEmitter` as outlined in the
RFC, but we are considering limiting the type to a minimal version that
is not coupled with RxJS, less complex, and also has better type safety
around emitting of values.
E.g. currently `EventEmitter.emit` can always be called without
any value, even though the output may be typed to always pass around
values of type `T`. This could cause subtle and confusing bugs.
PR Close#54217
This test ensures that the `ExpressionChanged...` error does not happen
when signals are updated in a view that is attached to `ApplicationRef`
but was already checked. This was fixed in 432afd1ef4
which actually consequently fixes it for regular `markForCheck` as well.
PR Close#54206
Matthieu Riegler