從服務訂閱數據時，類型 void 上不存在錯誤屬性訂閱？

Question

我在 angular 7 應用程序上工作我遇到錯誤屬性訂閱不存在類型

從服務訂閱數據時無效。

app.component.ts 上的訂閱數據 function 上顯示錯誤所以如果可能的話如何解決這個問題？

allReportCategories:any[];
ngOnInit() {


       this._displayreport.getallReportCategories().subscribe((data: any[]) => {  
        this.allReportCategories = data;  

      }); 
}

展示報告服務 ts

allReportCategories:any[];


getallReportCategories(){

    return 

     this.allReportCategories=[
    {
        "reportCategoryID": 1,
        "reportCategory": "Dashboard Parametric",
        "isDeleted": false,
        "menuIcon": "icon-home"
    },
    {
        "reportCategoryID": 2,
        "reportCategory": "Monitor Reports",
        "isDeleted": false,
        "menuIcon": "icon-list"
    },
    {
        "reportCategoryID": 3,
        "reportCategory": "Other Reports",
        "isDeleted": false,
        "menuIcon": "icon-docs"
    },
    {
        "reportCategoryID": 4,
        "reportCategory": "PCN Flow",
        "isDeleted": false,
        "menuIcon": "icon-list"
    },
    {
        "reportCategoryID": 5,
        "reportCategory": "Compliance By Document",
        "isDeleted": false,
        "menuIcon": "icon-home"
    }
];

  }

示例存在於 stackbliz 上，如下所示：

https://stackblitz.com/edit/create-1arrvm?file=app%2Fdisplayreport.service.ts

更具體地說明我的問題

我在這里改變了什么：

this._displayreport.getallReportCategories().subscribe

Answer 1

你需要創建 observable 來訂閱

例子：-

在顯示報告服務 ts

import { BehaviorSubject } from 'rxjs';


getallReportCategories(){

const allReportCategories = [
    {
        "reportCategoryID": 1,
        "reportCategory": "Dashboard Parametric",
        "isDeleted": false,
        "menuIcon": "icon-home"
    },
    {
        "reportCategoryID": 2,
        "reportCategory": "Monitor Reports",
        "isDeleted": false,
        "menuIcon": "icon-list"
    },
    {
        "reportCategoryID": 3,
        "reportCategory": "Other Reports",
        "isDeleted": false,
        "menuIcon": "icon-docs"
    },
    {
        "reportCategoryID": 4,
        "reportCategory": "PCN Flow",
        "isDeleted": false,
        "menuIcon": "icon-list"
    },
    {
        "reportCategoryID": 5,
        "reportCategory": "Compliance By Document",
        "isDeleted": false,
        "menuIcon": "icon-home"
    }
];


    return new BehaviorSubject(allReportCategories)

  }

在組件中

allReportCategories:any[];
ngOnInit() {


       this._displayreport.getallReportCategories().subscribe((data: any[]) => {  
        this.allReportCategories = data;  

      }); 
}