Angular mat-select 下拉 returns 一个未定义的值

Angular mat-select drop down returns an undefined value

HTML:

<mat-form-field>
    <mat-select placeholder="Section Types"(selectionChange)="selectSectionType($event)" disableRipple>
<mat-option *ngFor="let type of sectionTypes" [value]="type.value">
              {{type.viewValue}}
            </mat-option>
          </mat-select>
        </mat-form-field>

TS:

sectionTypes: DropDown[] = [
    {value: '0', viewValue: 'Horizontal'},
    {value: '1', viewValue: 'Vertical'}
  ];

selectSectionType(event: any){
    console.log("section type: " + event.target.value);
  }

当我 select 来自 mat-select 下拉列表的值时,方法 selectSectionType 被输入但 event.target.value returns 未定义。我想知道为什么。

感谢您的帮助

所选值:

selectSectionType(event: any){
    console.log("section type: " + event.value);
}

event.source.value

您有一个对象 MatSelect

event.source.MatSelect