angular - 如何在 mat-datepicker 中使用 GET 在输入字段中显示保存的日期？

Question

我开发了一个 mat-datepicker。我可以选择一个日期并将其保存在后端。如何在输入字段中显示保存的日期？

我的代码：

// HTML
 <mat-form-field appearance="fill">
   <mat-label>Datum</mat-label>
      <label>
        <input matInput [matDatepicker]="picker" formControlName="financial_year_start" required>
       </label>
      <mat-datepicker-toggle matSuffix [for]="picker"></mat-datepicker-toggle>
        <mat-datepicker #picker></mat-datepicker>
          <mat-error *ngIf="settingsContentForm.get('financial_year_start').hasError('required')">Input is required!</mat-error>
 </mat-form-field>

// TS
dateForm: FormGroup;
 ngOnInit() {
 this.dateForm = this.formBuilder.group({
      financial_year_start: [null, Validators.required],
    });
}

// My JSON
{
    "success": true,
    "mandant": {
        "mandantId": 1,
        "firm": "Test Ltd.",
        "financial_year_start": "Juli 1, 2018" // I want to display this value in the input, but in the format DD-MM-YYYY
    }
}

// My service for GET Date
public getCurrentMandantData(): Observable<any> {
    const url = `/current-mandant`;
    return this.http.get<any>(`${environment.baseUrl}` + url);
  }