初始化对象当tyscript中使用的strictnullchecks

发布于 2025-01-31 04:46:28 字数 1072 浏览 2 评论 0原文

我有一个称为iuser的接口，并在打字稿设置中使用strictnullchecks。我想在类似的类中使用iuser的变量：

class UserAccount {
    user: IUser;
}

上面的代码将生成错误：

属性'用户'没有初始化器，并且在构造函数中不确定。

我可以使用以下方式解决此问题：

class UserAccount {
    user: IUser;
    constructor() {
        user = new User();
    }
}

但是从运行时间角度来看，用户只能在显示后一段时间后设置。从服务器获取用户的数据有延迟。 用户的设置是通过rxjs可观察到的仅作用的。

我可以为user进行哪种类型的初始化，以便仅在以后设置它。设置用户 to null或undefined可能不正确，因为我使用strictnullchecks并表明该对象将会从一开始就存在。但是，在服务器调用完成之前，用户的有效对象不存在。

***更新****

这比上面的示例要好得多：

export class AddPersonDialogComponent {

  selectedPerson1: IPersonForTypeahead;
  selectedPerson2: IPersonForTypeahead;
  selectedPerson3: IPersonForTypeahead;

  ...
}

当用户从对话框中的三个3个下拉列表中选择它们时，分配了3 SelectedPerson对象。这三个属性一无所有，但如果用户从对话框中的下拉列中选择人员，则将设置它们。

原文

I have an interface called IUser and uses strictNullChecks in the typescript setting. I want to use a variable of IUser in the class like below:

class UserAccount {
    user: IUser;
}

The above code will generate the error:

Property 'user' has no initializer and is not definitely assigned in the constructor.

I can fix this with:

class UserAccount {
    user: IUser;
    constructor() {
        user = new User();
    }
}

But from a run time perspective, the user can be set only after a while after the display is complete. There is a latency for getting the data for the user from the server. The setting of the user is done through an RxJS observable which works only reactively.

What type of initialization I can do for user so that it can be set only later time. Setting user to null or undefined may not be correct because I use strictNullChecks and showing the intention that the object will be present from the beginning. But a valid object for user can't exist until the server call is complete.

*** UPDATE ****

This is a little more better example than the above:

export class AddPersonDialogComponent {

  selectedPerson1: IPersonForTypeahead;
  selectedPerson2: IPersonForTypeahead;
  selectedPerson3: IPersonForTypeahead;

  ...
}

The 3 selectedPerson objects are assigned values when the user select them from three 3 dropdowns in the dialog. These three properties start with nothing but if the user select people from a drop down in the dialog, they are set.

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你げ笑在眉眼 2025-02-07 04:46:28

您可以将用户量的使用量成为可观察的，这样：

userAccount$: Observable<UserAccount> = this.service.getUser().pipe(
    map(user => new UserAccount(user))
);

此处的想法是不要构造您的userAccount，直到您拥有所有需要的数据。这与您的想法“ ”一致，但是在服务器调用完成之前，不能存在一个有效的用户对象”。

You could make your usage of UserAccount to be an observable, like this:

userAccount$: Observable<UserAccount> = this.service.getUser().pipe(
    map(user => new UserAccount(user))
);

The idea here is to not construct your UserAccount until you have all the data needed to do so. This goes along with your idea "But a valid object for user can't exist until the server call is complete" .

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