typescript Angular2 EXCEPTION 没有 String 的提供者
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Angular2 EXCEPTION No provider for String
提问by Whisher
I've got a brand new app create with a ng-cli with this very simple code ^^
我用这个非常简单的代码用 ng-cli 创建了一个全新的应用程序^^
import { Component } from '@angular/core';
@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css']
})
export class AppComponent {
constructor(private my: string) {}
}
and I've got in the console
我进入了控制台
EXCEPTION: No provider for String!
例外：没有 String 的提供者！
I don't see any error in the code so what's wrong !
我在代码中没有看到任何错误，所以出了什么问题！
In ng-book I can read
在 ng-book 我可以阅读
export class Article {
title: string;
link: string;
votes: number;
constructor(title: string, link: string, votes?: number) {
this.title = title;
this.link = link;
this.votes = votes || 0;
}
}
Take a look at
看一眼
https://github.com/Microsoft/TypeScriptSamples/blob/master/greeter/greeter.ts
https://github.com/Microsoft/TypeScriptSamples/blob/master/greeter/greeter.ts
回答by AJT82
Error in constructor:
构造函数中的错误：
export class AppComponent {
constructor(private my: string) {}
}
private my: stringshould not be injected in the constructor, but outside, here assuming it's a variable you want to use in your component.
private my: string不应注入构造函数中，而应注入外部，这里假设它是您要在组件中使用的变量。
export class AppComponent {
private my: string;
constructor() {
this.my = 'Hello!'; // if you want to assign a value (in the constructor) to your string, do it here!
}
}
I suggest you start of with the Tutorialfrom the beginning, so you learn the basics of Angular :)
我建议你从教程开始，这样你就可以学习 Angular 的基础知识:)
EDIT, the latter part you added is a class e.g for typing your object, not a component, for a typed Object of class Article, this is valid syntax:
编辑，您添加的后一部分是一个类，例如用于键入您的对象，而不是组件，对于类文章的类型化对象，这是有效的语法：
export class Article {
title: string;
link: string;
votes: number;
constructor(title: string, link: string, votes?: number) {
this.title = title;
this.link = link;
this.votes = votes || 0;
}
}
Then you can import this class to your AppComponent, and use to assign an Articleobject.
然后您可以将此类导入到您的AppComponent, 并用于分配Article对象。
import { Component } from '@angular/core';
import { Article } from './your.path'
@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css']
})
export class AppComponent {
article: Article = new Article('titleHere', 'linkHere', 3)
constructor() {}
}
回答by saber tabatabaee yazdi
I had this error and can solve it
我有这个错误并且可以解决它
just need to re-run the build process
只需要重新运行构建过程
by stopping it with cntrl+c
用 cntrl+c 停止它
and ionic serveagain
并ionic serve再次
or angular command
或角度命令
