[英]Angular2 EXCEPTION No provider for String
I've got a brand new app create with a ng-cli with this very simple code ^^ 我有一个全新的应用程序使用ng-cli创建这个非常简单的代码^^
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 而且我已进入控制台了
EXCEPTION: No provider for String! EXCEPTION:没有String的提供者!
I don't see any error in the code so what's wrong ! 我没有在代码中看到任何错误,所以有什么不对!
In ng-book I can read 在ng-book中,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;
}
}
https://github.com/Microsoft/TypeScriptSamples/blob/master/greeter/greeter.ts https://github.com/Microsoft/TypeScriptSamples/blob/master/greeter/greeter.ts
Error in constructor: 构造函数中的错误:
export class AppComponent {
constructor(private my: string) {}
}
private my: string
should not be injected in the constructor, but outside, here assuming it's a variable you want to use in your component. private my: string
不应该在构造函数中注入,但在外面,这里假设它是你想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 Tutorial from the beginning, so you learn the basics of Angular :) 我建议你从一开始就开始使用Tutorial ,这样你就可以学习Angular的基础知识:)
EDIT, the latter part you added is a class eg for typing your object, not a component, for a typed Object of class Article, this is valid syntax: 编辑,你添加的后一部分是一个类,例如用于键入你的对象而不是组件,用于类别文章的类型化对象,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 Article
object. 然后,您可以将此类导入
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() {}
}
I had this error and can solve it 我有这个错误,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 通过cntrl + c停止它
and ionic serve
again 和
ionic serve
再次ionic serve
or angular command 或角度命令
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