Angular 2 (+Dart) inline conditionals: Is the second condition evaluated if the first is false? How to solve?

2
votes

This is the code in my component.html (Angular Dart template):

<div *ngIf="selectedOffer!=null && !selectedOffer.isBotenOffer">...</div>

This is the exception I get:

EXCEPTION: NoSuchMethodError: The getter 'isBotenOffer' was called on null. Receiver: null Tried calling: isBotenOffer

selectedOffer my be null sometimes. But why is the second statement evaluated if the first is false? And how can I around this best?

2
angulardartangular-dartangular-template

2 Answers

4
votes

Angular will write this into the generated template file:

_NgIf_0_5.ngIf = ((ctx.selectedOffer != null) && !ctx.selectedOffer.isBotenOffer);

So it shouldn't evaluate selectedOffer.isBotenOffer if selectedOffer is null. However, you may be hitting a bug that was just fixed in dart2js: https://github.com/dart-lang/sdk/commit/fe7baee84828e109a49920c2572f3917e5ff8ca5

You might hit this issue if you are setting selectedOffer in your component's constructor, but doing an early return in the constructor.

4
votes

No, with && short-circuit evaluation stops evaluating the 2nd part when the first is false - the same as in normal Dart code.