Angular2 @Injectable 不起作用

Question

我有一个 @Injectable 类，在 Service.ts create 中有一个 get 函数。此函数应返回一个数组并获取任何数组。但它返回null。如果我直接在@Component 中写这个，那么它确实得到了数组。我究竟做错了什么？

service.ts

@Injectable()
export class Arr_selected {
  private arr = [];
  get(arr_selected: any[]){
      for(let key in arr_selected) {
          if (arr_selected.hasOwnProperty(key)) {
              this.arr.push([key]);
              return this.arr;
          }
      }
      console.log(this.arr);

  }

} 

组件.ts

import {Arr_selected} from './service.ts';
export class Component implements DoCheck, OnChanges, OnInit {
....
constructor( public arr_selected: Arr_selected)
.....

ngOnInit{

     let chk = this.ChkBoxValue;

     let arr = [];

/// **this not working Array is null**/////
     arr=(this.arr_selected.get(this.ChkBoxValue));

/// **this is working Array is not null**////
     for (let key in this.ChkBoxValue) {
            if (this.ChkBoxValue.hasOwnProperty(key)) {
              arr.push(this.ChkBoxValue[key]);
         }
       }
        console.log(arr); 
}}

Answer 1

我认为下面应该可以工作

@Injectable()
export class Arr_selected {
      get(arr_selected: any[]){
          arr = [];
          for(let key in arr_selected) {
              if (arr_selected.hasOwnProperty(key)) {
                  arr.push([key]);
                  return this.arr;
              }
          }
          console.log(this.arr);

      }

我认为“this”运算符给你造成了问题。您还在组件中定义了 arr 。这可能与使用哪个 arr 发生冲突。

Answer 2

Above code you have written your file name as service.ts

并从 ./servece.ts 导入

   import {Arr_selected} from'./servece.ts;

可能是这里的打字错误， 您是否也在组件提供商中添加您的服务？。