angulartypescriptangular2-directivesngfor

Reputation: 364687

Exception: Can't bind to 'ngFor' since it isn't a known native property

What am I doing wrong?

import {bootstrap, Component} from 'angular2/angular2'

@Component({
  selector: 'conf-talks',
  template: `<div *ngFor="talk of talks">
     {{talk.title}} by {{talk.speaker}}
     <p>{{talk.description}}
   </div>`
})
class ConfTalks {
  talks = [ {title: 't1', speaker: 'Brian', description: 'talk 1'},
            {title: 't2', speaker: 'Julie', description: 'talk 2'}];
}
@Component({
  selector: 'my-app',
  directives: [ConfTalks],
  template: '<conf-talks></conf-talks>'
})
class App {}
bootstrap(App, [])

The error is

EXCEPTION: Template parse errors:
Can't bind to 'ngFor' since it isn't a known native property
("<div [ERROR ->]*ngFor="talk of talks">

Upvotes: 360

Answers (17)

Akshay S Patil

Reputation: 31

Use this

<div *ngFor="let talk of talks"> 
   {{talk.title}} 
   {{talk.speaker}}
   <p>{{talk.description}}</p>
</div>

You need to specify variable to iterate over an array of an object

Upvotes: 3

drec0xy

Reputation: 11

For me the component was not properly imported in app.module.ts file. After importing it everything works fine

@NgModule({
    declarations: [
      YourComponent,
      OtherComponents
    ],
    
    imports: [...]

)}

Upvotes: 1

Jeyson Mg

Reputation: 160

In my case I was not declaring the loop variable inside the for loop I had

<div *ngFor="pizza of pizzas; index as i">

instead of

<div *ngFor="let pizza of pizzas; index as i">

After declaring it with 'let' it just worked for me.

Upvotes: 0

hamthiii

Reputation: 117

Had the same problem because I had used
*ngFor='for let card of cards'
instead of:
*ngFor='let card of cards'

had for in the beginning like some "for loop"s which was wrong here
it worked, but had the error

Upvotes: 2

user3727574

Reputation: 136

In my case,There should be no space between = and ",

e.g. wrong :

*ngFor = "let talk of talks"

right :

*ngFor="let talk of talks"

Upvotes: 1

Robin Mathur

Reputation: 587

Just to cover one more case when I was getting the same error and the reason was using in instead of of in iterator

Wrong way let file in files

Correct way let file of files

Upvotes: 4

Rsona

Reputation: 91

You should use let keyword as to declare local variables e.g *ngFor="let talk of talks"

Upvotes: 8

Roy Touw

Reputation: 178

In my case, the module containing the component using the *ngFor resulting in this error, was not included in the app.module.ts. Including it there in the imports array resolved the issue for me.

Upvotes: 1

Mark Rajcok

Reputation: 364687

I missed let in front of talk:

<div *ngFor="let talk of talks">

Note that as of beta.17 usage of #... to declare local variables inside of structural directives like NgFor is deprecated. Use let instead.

<div *ngFor="#talk of talks"> now becomes <div *ngFor="let talk of talks">

Original answer:

I missed # in front of talk:

<div *ngFor="#talk of talks">

It is so easy to forget that #. I wish the Angular exception error message would instead say:
you forgot that # again.

Upvotes: 784

rlaures

Reputation: 335

Also don't try to use pure TypeScript in this... I wanted to more correspond to for usage and use *ngFor="const filter of filters" and got the ngFor not a known property error. Just replacing const by let is working.

As @alexander-abakumov said for the of replaced by in.

Upvotes: 3

Alferd Nobel

Reputation: 3949

In angular 7 got this fixed by adding these lines to .module.ts file:

import { CommonModule } from '@angular/common'; imports: [CommonModule]

Upvotes: 22

Alexander Abakumov

Reputation: 14539

Another typo leading to the OP's error could be using in:

<div *ngFor="let talk in talks">

You should use of instead:

<div *ngFor="let talk of talks">

Upvotes: 95

paulsm4

Reputation: 121649

I forgot to annotate my component with "@Input" (Doh!)

book-list.component.html (Offending code):

<app-book-item
  *ngFor="let book of book$ | async"
  [book]="book">  <-- Can't bind to 'book' since it isn't a known property of 'app-book-item'
</app-book-item>

Corrected version of book-item.component.ts:

import { Component, OnInit, Input } from '@angular/core';

import { Book } from '../model/book';
import { BookService } from '../services/book.service';

@Component({
  selector: 'app-book-item',
  templateUrl: './book-item.component.html',
  styleUrls: ['./book-item.component.css']
})
export class BookItemComponent implements OnInit {

  @Input()
  public book: Book;

  constructor(private bookService: BookService)  { }

  ngOnInit() {}

}

Upvotes: 3