By default, the value and validation status of a `FormControl` updates
whenever its value changes. If an application has heavy validation
requirements, updating on every text change can sometimes be too expensive.
This commit introduces a new option that improves performance by delaying
form control updates until the "blur" event. To use it, set the `updateOn`
option to `blur` when instantiating the `FormControl`.
```ts
// example without validators
const c = new FormControl(, { updateOn: blur });
// example with validators
const c= new FormControl(, {
validators: Validators.required,
updateOn: blur
});
```
Like in AngularJS, setting `updateOn` to `blur` will delay the update of
the value as well as the validation status. Updating value and validity
together keeps the system easy to reason about, as the two will always be
in sync. It's also worth noting that the value/validation pipeline does
still run when the form is initialized (in order to support initial values).
Closes#7113
This commit fixes a regression where `ngModel` no longer syncs
letter by letter on Android devices, and instead syncs at the
end of every word. This broke when we introduced buffering of
IME events so IMEs like Pinyin keyboards or Katakana keyboards
wouldn't display composition strings. Unfortunately, iOS devices
and Android devices have opposite event behavior. Whereas iOS
devices fire composition events for IME keyboards only, Android
fires composition events for Latin-language keyboards. For
this reason, languages like English don't work as expected on
Android if we always buffer. So to support both platforms,
composition string buffering will only be turned on by default
for non-Android devices.
However, we have also added a `COMPOSITION_BUFFER_MODE` token
to make this configurable by the application. In some cases, apps
might might still want to receive intermediate values. For example,
some inputs begin searching based on Latin letters before a
character selection is made.
As a provider, this is fairly flexible. If you want to turn
composition buffering off, simply provide the token at the top
level:
```ts
providers: [
{provide: COMPOSITION_BUFFER_MODE, useValue: false}
]
```
Or, if you want to change the mode based on locale or platform,
you can use a factory:
```ts
import {shouldUseBuffering} from 'my/lib';
....
providers: [
{provide: COMPOSITION_BUFFER_MODE, useFactory: shouldUseBuffering}
]
```
Closes#15079.
PR Close#15256
Observable subscriptions from previous validation runs should be canceled
before a new subscription is created for the next validation run.
Currently the subscription that sets the errors is canceled properly,
but the source observable created by the validator is not. While this
does not affect validation status or error setting, the source
observables will incorrectly continue through the pipeline until they
complete. This change ensures that the whole stream is canceled.
AsyncValidatorFn previously had an "any" return type, but now it more
explicitly requires a Promise or Observable return type. We don't
anticipate this causing problems given that any other return type
would have caused a runtime error already.
Kara
Victor Berchet
Kara Erickson
Miško Hevery
Tobias Bosch
Jason Aden