angular – 自定义验证访问表单组件

我的模板

<input type="tekst" id="startDate" name="startDate" [(ngModel)]="model.startDate" #startDate="ngModel" >

<input type="tekst" id="endDate" name="endDate" [(ngModel)]="model.endDate" #endDate="ngModel" customValidator>

我的验证员

...
@Directive({
    SELEctor: '[customValidator][ngModel][customValidator][formControl]',providers: [
        provide : NG_VALIDATORS,useExisTing : forWARDRef(() = > CustomValidator),Multi : true
    }]
})

export class CustomValidator impelments Validator {
    constructor(){}

    validate(c : FormControl) : {[key : String] : any} {

        // HOW TO ACCESS startDate CONTROL HERE? OR ITS VALUE? OR THE MODEL
    }