在angular2 +中使用素数ng的默认值问题中自动选择下拉列表

Question

我正在使用带有angular5的prime-ng的p-dropdown。当我打开一个下拉列表包含项目列表的屏幕时，我想从ts中自动选择下拉列表的值。

请注意：它在其他屏幕上均有效，仅在该特定屏幕上不起作用。

下面是我的component.html

<div class="ui-g-6">
  <p-dropdown #company="ngModel" [options]="companies" [autoWidth]="false" 
    [style]="{'width':'100%'}" placeholder="Select a Company" filter="true" 
   [(ngModel)]="selectedCompany" (onChange)="setBranches()"
    name="company" [autoDisplayFirst]="false" required></p-dropdown>
</div>

下面是ts文件的代码，

this.companies = [];
if (this.customerGroups) {
    this.customerGroups.customers.forEach((customer) => {
        this.companies.push({
            label: customer.company,
            value: customer
        });
    });
} else {
    this.companies.push({
        label: this.campaign.customer.company,
        value: this.campaign.customer
    });
}
this.companies = JSON.parse(JSON.stringify(this.companies));
this.setSelectedCompany();


setSelectedCompany() {
        this.companies.forEach((company, index) => {
            if (this.invoice.id === null || this.invoice.id === undefined) {
                if (company.label === this.campaign.customer.company) {
                    // this.selectedCompany = company.value;
                    this.selectedCompany = this.companies[index].value;
                }
            } else {
                if (company.label === this.invoice.campaign.customer.company) {
                    // this.selectedCompany = company.value;
                    this.selectedCompany = this.companies[index].value;
                }
            }
        });

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我认为这可能与屏幕渲染有关，任何人都可以帮忙。