自动完成[displayWith]不显示名称

Question

我正在为我的项目使用自动完成材料，但我不明白如何使用 [displayWith]。我尝试了一些示例，但不在 html 中显示名称，仅显示 id。

我的html代码：

<form [formGroup]="editClientForm">
  <input formControlName="city_id" id="city_id" matInput placeholder="Select City*" aria-label="State" [matAutocomplete]="auto1"
    autoActiveFirstOption [formControl]="city">
  <mat-autocomplete #auto1="matAutocomplete" [displayWith]="displayFnCity">
    <mat-option (onSelectionChange)="updateForm($event, city.city_id, 'city_id')" *ngFor="let city of filteredOptionsCity | async"
      [value]="city.name">
      {{ city.name }}
    </mat-option>
  </mat-autocomplete>
</form>

我的 ts 组件：

  cityid = 0;
  filteredOptionsCity: any;
  city: FormControl = new FormControl();
  editClientForm: FormGroup;
    this.editClientForm = this.fb.group({
      'city_id': new FormControl('', Validators.required),
         });
  ngOnInit() {
    this.filteredOptionsCity = this.city.valueChanges.pipe(
      startWith(''),
      map(value => this.filterCity(value))
    );
}

  populateForm() {
    this.activatedRoute.params.subscribe(
      params => {
        this.clientService.getClientById(params['id']).subscribe(
          client => {
            this.client = client;
            console.log(client)
            this.editClientForm.controls['city_id'].setValue(client.city);
            console.log(client.city);
          }
        );
      }
    );
  }
  // City
  filterCity(val: string): City[] {
    if (val) {
      let filterValue = val.toLowerCase();
      console.log(this.cityes)
      return this.cityes.filter(city => city.name.toLowerCase().startsWith(filterValue));
    }

    return this.cityes;
  }

  updateForm(ev: any, idd: any, componentid: any) {

    if (ev.isUserInput) {
      if (componentid === 'city_id') {
        this.cityid = idd;
        this.editClientForm['controls']['city_id'].setValue(ev.source.value);
      } else {
        console.log('test');
      }
    }
  }

我的班级客户：

export class Client {  
city: City[];}

我的班级城市：

export class City {
  city_id: string;
  name: string; }

在 html 中显示 ccity_id，我想要城市名称。

我尝试使用这段代码，但没有发生任何事情：

   getName(productid: string) {
      const [filteredProdG] = this.cityes.filter(pt => pt.city_id === productid);

   if (typeof filteredProdG !== 'undefined' && productid === filteredProdG.city_id) {
       return filteredProdG.name;
     } 
   }

1.   displayFnCity(city?: City): string {
         console.log(city ? city.name : undefined) //show undefined
     return city ? city.name : undefined;
      }
2.  displayFnCity(city) {
    console.log(city.name) //show undefined
    return city.name;
  }

3.如果我尝试[displayWith]="displayFn"或[displayWith]="displayFnCity" 仅在html中显示id_city

请问您知道如何解决这个问题吗？

Answer 1

该[displayWith]函数将传递该[value]对象。因为在您的情况下您使用了[value]="city.name"您不需要使用[displayWith]，因为默认情况下自动完成将显示任何[value]内容。通常，人们会使用[displayWith]when[value]绑定到人类无法识别的字符串的对象。例如，如果您使用了[value]="city"，那么您也想使用[displayWith]="displayFnCity"(your #1)。