Angular Elements - pass a complicated input to my web component

问题

I started lately to play a little bit with angular elements that was released in angular V6, I opened a small sandbox project for that purpose. https://github.com/Slash7GNR/ndv-angular-elements Now I've tried to add a more complicated input to my web component - I've tried to add an array input as follows: in app.component.ts I've added:

@Input() welcomeMessages: string[];

and in the template I've added:

<div *ngFor="let message of welcomeMessages; let index = index">
    {{index}} - {{message}}
</div>

Then, I've created a static html file and added the following code: (pls-wrk is a web component generated by angular elements feature)

<pls-wrk></pls-wrk>
<script>
let arr = [“wow”,”wow2"];
let elementByTag = document.getElementsByTagName(‘pls-wrk’)[0];
elementByTag.setAttribute(“welcome-messages”, arr);
</script>
<script src="ndv-elements.js"></script>

I’m getting the following error:

Uncaught Error: Cannot find a differ supporting object ‘wow,wow2’ of type ‘string’. NgFor only supports binding to Iterables such as Arrays.

I've tried as well to bind an array via the element itself like this:

<pls-wrk welcome-messages=”[‘wow’,wow2']”></pls-wrk>

But neither this worked.

I've tried as well to bind an input which is an object, but I couldn't see the result in the html.

Anyone here who could successfully pass an array / an object as an input to an angular element?

回答1:

So I found the answer, I had two main problems:

I had to add the angular elements script (ndv-elements.js) before initializing the attributes.
The thing with HTML attribute, is that they are all passed as strings, in contrast to angular or other framework where you can pass objects / arrays, so when using setAttribute method, the attribute is being initialized as a string which causes a problem with inputs that are objects / arrays, the solution is to set the attribute as follows: elementByTag.welcomeMessages = array;

So the full solution will be:

<pls-wrk>
</pls-wrk>
<script src="ndv-elements.js"></script>
<script>
let arr = ['a1','a2','a3'];
let wrk = document.querySelector('pls-wrk');
wrk.welcomeMessages = arr;
</script>

References:

https://github.com/angular/angular/issues/24415

https://medium.com/@gilfink/using-complex-objects-arrays-as-props-in-stencil-components-f2d54b093e85

来源：https://stackoverflow.com/questions/50793080/angular-elements-pass-a-complicated-input-to-my-web-component

标签

angular

angular-elements