使用自动完成过滤对象内的数组

Question

我试图使用两个过滤器方法基于字符串过滤对象内的数组。这是我的对象的样子。

[
  {
    "cat": "Accommodation and Food Service Activities",
    "value": [
      {
        "sic": "55",
        "desc": "Accommodation"
      },
      {
       "sic": "56",
        "desc": "Food and beverage service activities"
      }
    ]
  },
  {
    "cat": "Activities Of Extraterritorial Organisations and Bodies",
    "value": [
      {
       "sic": "99",
        "desc": "Activities of extraterritorial organisations and bodies"
      }
    ]
  }
] 

我正在尝试过滤value.desc并返回cat

这是我到目前为止所拥有的

filteredIndustries(industry: string) {
    if (industry) {
      return this.industries.filter(sector => {
        if (sector.value) {
          sector.value.findIndex( v => {
            return v.desc.toString().toLowerCase().indexOf(industry.toString().toLowerCase()) === 0;
          });
        }
      });
    } else {
      return this.industries;
    }

这是我的HTML，

 <md-input-container>
      <input mdInput placeholder="Industry" [mdAutocomplete]="auto" [formControl]="industryCtrl">
    </md-input-container>

    <md-autocomplete #auto="mdAutocomplete" [displayWith]="displayIndustry.bind(this)">
      <md-option *ngFor="let industry of filteredIndustry | async" [value]="industry">
        {{ industry.cat }}
      </md-option>
    </md-autocomplete>

因此，当我输入食物时，应该在value.desc上过滤并返回cat Accommodation and Food Service Activities

但即使我的返回结果为真，我也没有得到任何返回值。

非常感谢任何帮助。