Utilizing Angular 2 Component Input Binding with the Expression Mapping Function

Currently, I am working on a component that has an input of type array. 

class FooComponent  {  
@Input() selectedItemIds:String[];
}

I want to utilize a map expression in binding within the parent component.

<app-foo-component [selectedItemIds]='items.map(i=>i.Id)'><app-foo-component>

However, I encountered an Angular error stating:

Bindings cannot contain assignments...

So, I am seeking a solution to this issue.

**Please note: While I know how to achieve this in the component class, I am exploring if there is a way to do it through the template as well. The provided code snippet is concise and aimed at illustrating my attempted approach.**

angulartypescript

Answer №1

Prior to passing it to <app-foo-component>, make sure to invoke the map function in your *.ts file. If your component is getting constructed before the array is ready, consider creating a property to store it.

<app-foo-component *ngIf="itemsReady" [selectedItemIds]='items'><app-foo-component>

In your *.ts file, you can then define a function for mapping purposes:

itemsReady = false;

mapFunction() {
  // Perform your mapping here and set this.itemsReady = true when done
}

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