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fix(elements): correctly handle setting inputs to `undefined` (#36140) 

Previously, when an input property was initially set to `undefined` it
would not be correctly recognized as a change (and trigger
`ngOnChanges()`).

This commit ensures that explicitly setting an input to `undefined` is
correctly handled the same as setting the property to any other value.
This aligns the behavior of Angular custom elements with that of the
corresponding components when used directly (not as custom elements).

PR Close #36140
This commit is contained in:
George Kalpakas 2020-03-19 13:57:55 +02:00 committed by Misko Hevery
parent b14ac96750
commit 9ba46d9f88
2 changed files with 8 additions and 1 deletions
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6
packages/elements/src/component-factory-strategy.ts
View File

@ -133,7 +133,11 @@ export class ComponentNgElementStrategy implements NgElementStrategy {
return;
}
if (strictEquals(value, this.getInputValue(property))) {
// Ignore the value if it is strictly equal to the current value, except if it is `undefined`
// and this is the first change to the value (because an explicit `undefined` _is_ strictly
// equal to not having a value set at all, but we still need to record this as a change).
if (strictEquals(value, this.getInputValue(property)) &&
!((value === undefined) && this.unchangedInputs.has(property))) {
return;
}

3
packages/elements/test/component-factory-strategy_spec.ts
View File

@ -94,6 +94,7 @@ describe('ComponentFactoryNgElementStrategy', () => {
it('should call ngOnChanges with the change', () => {
expectSimpleChanges(componentRef.instance.simpleChanges[0], {
fooFoo: new SimpleChange(undefined, 'fooFoo-1', true),
falsyUndefined: new SimpleChange(undefined, undefined, true),
falsyNull: new SimpleChange(undefined, null, true),
falsyEmpty: new SimpleChange(undefined, '', true),
falsyFalse: new SimpleChange(undefined, false, true),
@ -104,11 +105,13 @@ describe('ComponentFactoryNgElementStrategy', () => {
it('should call ngOnChanges with proper firstChange value', fakeAsync(() => {
strategy.setInputValue('fooFoo', 'fooFoo-2');
strategy.setInputValue('barBar', 'barBar-1');
strategy.setInputValue('falsyUndefined', 'notanymore');
tick(16); // scheduler waits 16ms if RAF is unavailable
(strategy as any).detectChanges();
expectSimpleChanges(componentRef.instance.simpleChanges[1], {
fooFoo: new SimpleChange('fooFoo-1', 'fooFoo-2', false),
barBar: new SimpleChange(undefined, 'barBar-1', true),
falsyUndefined: new SimpleChange(undefined, 'notanymore', false),
});
}));
});