Angular 以模型驱动形式编程设置formControl的值

如何获得下面函数的底线来设置categories表单字段的值

ngOnInit() {
       this.findForm = this.formBuilder.group({
        categories: ['', [<any>Validators.required]],
        distanceNumber: ['', [<any>Validators.required]],
        distanceUnit: ['kilometers', [<any>Validators.required]],
        keywords: ['lemon', [<any>Validators.required]],
    });

    this.findForm.controls['categories'].updateValueAndValidity("shoe");
}

ngOnInit（）{
this.findForm=this.formBuilder.group({
类别：[''[Validators.required]]，
距离编号：[''，[Validators.required]]，
距离单位：['公里'，[Validators.required]]，
关键词：['lemon'，[Validators.required]]，
});
this.findForm.controls['categories'].updateValueAndValidity（“shoe”）；
}

this.findForm.get('categories').setValue("shoe");