嵌套在ngIf中的组件的Angular2 @ViewChild错误

Question

I'm working with ng2-select. To fetch the data dynamically, I'm following this method:

https://github.com/valor-software/ng2-select/issues/635

So first I select the component like so:

HTML:

<form #frecipientAddAccount="ngForm" novalidate>
     <ng-select #recipientBanks (selected)="selected($event)" placeholder="Select Bank"></ng-select>

componen.ts:

@ViewChild('recipientBanks') recipientBanks: SelectComponent

And I create the option elements with the fetched data like so:

ngOnInit(): void {
    (<any>this.recipientBanks).items = []
    let currencyTypeId = this.determineCurrencyType();
    let response = getRecipientBanksForCountry(this.data.dashboard.userCountryId, 'C', currencyTypeId);
    response.then((data) => {
        (<any>this.recipientBanks).items = data.list.map(function (obj) {
            return new SelectOptionComponent(obj.BankId, obj.Description)
        })
    })
}

And it is working so far. The problem is that the ng-select element needs to be nested in a couple of ngIf elements, but if I do so, suddenly the component (<any>this.recipientBanks) is undefined.

How can I still select the component when it is nested in ngIf s?

Answer 1

Instead of having the #recipientBanks in the div use it as below,

@ViewChild(SelectComponent) recipientBanks: SelectComponent

Update 1 :

Instead of using the ViewChild object and assign the properties you can use different object as the ViewChild() turns out to be undefined unless it is rendered in the DOM

 <ng-select #recipientBanks (selected)="selected($event)" [items]="dropDownItems" placeholder="Select Bank"></ng-select>

Assign the data to dropDownItems variable instead of <any>this.recipientBanks).items

Alternatively you can use [hidden] instead of *ngIf

Answer 2

我将ngOnInit替换为ngAfterViewInit ，现在它可以工作了！