Question

所以我一直收到这个错误＆＃34; TypeError：无法读取属性＆＃39; otherDocumentaryEvidence＆＃39;未定义＆＃34;。我知道我需要以某种方式初始化这个对象，但我不确定这个过程。我的理解是在ngOnInit阶段从模板服务

定义对象

ngOnInit(): void {
    this._templateService
        .getTemplateSnapshot(this.template)
        .responseData()
        .subscribe(templateSnapStream => {
            return this.shareCase = templateSnapStream.result;
        })
}

我的对象看起来像这样

export class ShareCase {
    shareCaseReason?: string;
    caseDetails?: ICasedeit;
    involvedPersonsAndOrganisations?: IInvolved;
    policeOfficer?: IPolice;
    incidents?: IIncident;
    offences?: IOffence;
    suspect?: ISuspectDetails
    witnessStatements?: IStatements;
    interviewNotes?: IIncident;
    notebookEntries?: INotebook;
    victims?: IVictim;
    witnesses?: IWitness;
    physicalEvidence?: IEvidence;
    otherDocumentaryEvidence?: IDocEvidence;
}

在我的组件代码中，我在构造函数中初始化Share Case对象和otherDocumentaryEvidence对象，如下所示：

 this.shareCase = new ShareCase();
 this.shareCase.otherDocumentaryEvidence = new IDocEvidence();

但我仍然得到同样的错误？我不确定为什么会这样。我的模板中调用此对象的行也如下所示

 <div *ngIf='shareCase && shareCase.case.otherDocumentaryEvidence && shareCase.case.otherDocumentaryEvidence.length > 0'>

非常感谢任何帮助！

Answer 1

您错过了*ngIf

中的其他支票

<div *ngIf='shareCase && 
            shareCase.case && 
            shareCase.case.otherDocumentaryEvidence && 
            shareCase.case.otherDocumentaryEvidence.length > 0'>

您缺少shareCase.case支票

Answer 2

尝试添加null / undefined check的问号。

<div *ngIf='shareCase && shareCase.case?.otherDocumentaryEvidence && shareCase.case?.otherDocumentaryEvidence.length > 0'>

如何初始化OnInit中定义的嵌套对象？ Angular2

2 个答案: