Unable to call a component's method from a different component in Angular 7

Question

Unable to call a component's method from a different component in Angular 7

How can I call the toggleSidebar() method of the SidebarComponent from the HeaderComponent using the callToggleSidebarOnToggleSidebarBtn() method? I am encountering an error that I cannot comprehend. What is the correct way to use a method of one component in another?

I have imported the SidebarComponent into the HeaderComponent. In the constructor of HeaderComponent, I added the SidebarComponent to use one of its methods. Even after removing the callToggleSidebarOnToggleSidebarBtn() method from header.component.ts, I still face the same issue.

sidebar.component.html :

<div id="sidebar" class="bg-gray">
<a href="" class="nav-link"><i class="fa fa-calendar"></i> Event</a>
<a href="" class="nav-link"><i class="fa fa-user-circle-o"></i> Profile</a>
<a href="" class="nav-link"><i class="fa fa-commenting-o"></i> Chat</a>
<a href="" class="nav-link"><i class="fa fa-gear"></i> Setting</a>
<a href="" class="nav-link"><i class="fa fa-question-circle-o"></i> Help</a>
<a href="" class="nav-link"><i class="fa fa-sign-out"></i> Log out</a>

header.component.html :

<div>
  <nav class="navbar navbar-expand-lg d-flex justify-content-between fixed-top">
    <button class="btn" (click)="callToggleSidebarOnToggleSidebarBtn()"><i class="fa fa-reorder"></i></button>
    <div class="d-flex p-0 m-0">
      <a href="#" class="nav-link d-none d-lg-block">Event</a>
      <a href="#" class="nav-link d-none d-lg-block">Contact Us</a>
      <a href="#" class="nav-link d-none d-lg-block">About Us</a>
      <a href="#" class="nav-link d-none d-lg-block"><i class="fa fa-user-circle"></i></a>
    </div>
    <div class="d-flex">
      <a href="#" class="nav-link"><i class="fa fa-bell"></i></a>
      <a href="#" class="nav-link"><i class="fa fa-globe"></i></a>
    </div>
  </nav>
  <div class="d-sm-flex align-items-center justify-content-between" id="secondMenu">
    <div id="logoContainer">
      <img src="../assets/images/logo.png" alt="" id="logo">
    </div>
    <div class="input-group">
      <div class="input-group-prepend">
        <button class="input-group-text btn dropdown-toggle" data-toggle="dropdown">Meeting</button>
        <div class="dropdown-menu">
          <a class="dropdown-item" class="dropdown-item">Action</a>
          <a class="dropdown-item" class="dropdown-item">Another action</a>
          <a class="dropdown-item" class="dropdown-item">Something else here</a>
        </div>
      </div>
      <input type="text" class="form-control" placeholder="What are you looking for ?" aria-label="Search">
      <div class="input-group-append">
        <button class="btn" type="submit"><i class="fa fa-search"></i></button>
      </div>
    </div>
  </div>
<div>

I expected to be able to toggle the content of sidebar.component.html by clicking on the button at the top left of the header. However, I encountered the following error:

ERROR Error: Uncaught (in promise): Error: StaticInjectorError(AppModule) 
[HeaderComponent -> SidebarComponent]: 
  StaticInjectorError(Platform: core)[HeaderComponent -> SidebarComponent]: 
    NullInjectorError: No provider for SidebarComponent!
Error: StaticInjectorError(AppModule)[HeaderComponent -> SidebarComponent]: 
  StaticInjectorError(Platform: core)[HeaderComponent -> SidebarComponent]: 
    NullInjectorError: No provider for SidebarComponent!
    at NullInjector.push../node_modules/@angular/core/fesm5/core.js.NullInjector.get (core.js:3228)
at resolveToken (core.js:3473)
at tryResolveToken (core.js:3417)
at StaticInjector.push../node_modules/@angular/core/fesm5/core.js.StaticInjector.get (core.js:3314)
at resolveToken (core.js:3473)
at tryResolveToken (core.js:3417)
at StaticInjector.push../node_modules/@angular/core/fesm5/core.js.StaticInjector.get (core.js:3314)
at resolveNgModuleDep (core.js:19784)
at NgModuleRef_.push../node_modules/@angular/core/fesm5/core.js.NgModuleRef_.get (core.js:20473)
at resolveDep (core.js:20844)
at resolvePromise (zone.js:831)
at resolvePromise (zone.js:788)
at zone.js:892
at ZoneDelegate.push../node_modules/zone.js/dist/zone.js.ZoneDelegate.invokeTask (zone.js:423)
at Object.onInvokeTask (core.js:16147)
at ZoneDelegate.push../node_modules/zone.js/dist/zone.js.ZoneDelegate.invokeTask (zone.js:422)
at Zone.push../node_modules/zone.js/dist/zone.js.Zone.runTask (zone.js:195)
at drainMicroTaskQueue (zone.js:601)

angular typescript angular-cli angular-components angular-cli-v7

Answer 1

Answer №1

Components are not to be treated as dependencies that can be injected.

If you wish to achieve a specific functionality, locate the sidebar within your header and create a reference for it:

<app-sidebar #sidebarReference></app-sidebar>

You now have the option to utilize it in your template:

<button (click)="sidebarReference.toggleSidebar()">...</button>

Alternatively, you can access it from your component:

@ViewChild(SidebarComponent) sidebar: SidebarComponent;
// or, if multiple sidebars exist in the template,
@ViewChild('sidebarReference') sidebar: SidebarComponent;
this.sidebar.toggleSidebar();

Answer 2

Components are not to be treated as dependencies that can be injected.

If you wish to achieve a specific functionality, locate the sidebar within your header and create a reference for it:

<app-sidebar #sidebarReference></app-sidebar>

You now have the option to utilize it in your template:

<button (click)="sidebarReference.toggleSidebar()">...</button>

Alternatively, you can access it from your component:

@ViewChild(SidebarComponent) sidebar: SidebarComponent;
// or, if multiple sidebars exist in the template,
@ViewChild('sidebarReference') sidebar: SidebarComponent;
this.sidebar.toggleSidebar();

Answer 3

Answer №2

To streamline the process, rather than directly creating an instance of a sidebar component within the Header component, it is more efficient to establish a service named appService.ts. This can be achieved by executing the following command:

ng generate service app

Within this service file, incorporate the provided code snippet:

import { Injectable } from '@angular/core';
import { Subject } from 'rxjs';

@Injectable({
  providedIn: 'root'
})
export class AppService {

  flagChange:Subject<boolean> = new Subject<boolean>();

  constructor() { }

  setFlag(flagValue){
    this.flagChange.next(flagValue);
  }
}

After setting up the service, proceed to inject the service instance into our header.component.ts:

import { Component, OnInit } from '@angular/core';
import { AppService } from './app.service';

@Component({
  selector: 'app-header',
  templateUrl: './header.component.html',
  styleUrls: ['./header.component.css']
})
export class HeaderComponent implements OnInit {

   flag:boolean = false;

  constructor(private appService :  AppService) { }

  ngOnInit() {
  }

  callToggleSidebarOnToggleSidebarBtn() {

    this.appService.setFlag(!this.flag);
  }
}

In the sidebar.component.ts, make the necessary updates as shown below:

import { Component, OnInit } from '@angular/core';
import * as $ from 'jquery';
import { AppService } from './app.service';

@Component({
  selector: 'app-sidebar',
  templateUrl: './sidebar.component.html',
  styleUrls: ['./sidebar.component.css']
})
export class SidebarComponent implements OnInit {

  constructor(private appService: AppService) { }

  ngOnInit() {
   this.appService.flagChange.subscribe((flag) => {
      $("#sidebar").animate({width: 'toggle'});
    })
  }
}

By implementing this structure, when the user interacts with the icon, the flag status in the header component undergoes a toggle effect. This modification is then relayed and captured via the flagChange variable in the AppService utilizing the next() function, subsequently observed through the subscribe method within the sidebar component.

Answer 4

To streamline the process, rather than directly creating an instance of a sidebar component within the Header component, it is more efficient to establish a service named appService.ts. This can be achieved by executing the following command:

ng generate service app

Within this service file, incorporate the provided code snippet:

import { Injectable } from '@angular/core';
import { Subject } from 'rxjs';

@Injectable({
  providedIn: 'root'
})
export class AppService {

  flagChange:Subject<boolean> = new Subject<boolean>();

  constructor() { }

  setFlag(flagValue){
    this.flagChange.next(flagValue);
  }
}

After setting up the service, proceed to inject the service instance into our header.component.ts:

import { Component, OnInit } from '@angular/core';
import { AppService } from './app.service';

@Component({
  selector: 'app-header',
  templateUrl: './header.component.html',
  styleUrls: ['./header.component.css']
})
export class HeaderComponent implements OnInit {

   flag:boolean = false;

  constructor(private appService :  AppService) { }

  ngOnInit() {
  }

  callToggleSidebarOnToggleSidebarBtn() {

    this.appService.setFlag(!this.flag);
  }
}

In the sidebar.component.ts, make the necessary updates as shown below:

import { Component, OnInit } from '@angular/core';
import * as $ from 'jquery';
import { AppService } from './app.service';

@Component({
  selector: 'app-sidebar',
  templateUrl: './sidebar.component.html',
  styleUrls: ['./sidebar.component.css']
})
export class SidebarComponent implements OnInit {

  constructor(private appService: AppService) { }

  ngOnInit() {
   this.appService.flagChange.subscribe((flag) => {
      $("#sidebar").animate({width: 'toggle'});
    })
  }
}

By implementing this structure, when the user interacts with the icon, the flag status in the header component undergoes a toggle effect. This modification is then relayed and captured via the flagChange variable in the AppService utilizing the next() function, subsequently observed through the subscribe method within the sidebar component.

Answer 5

Answer №3

In order to address this issue, I began by removing the import of the sidebar in header.component.ts along with its constructor. The final version of my header.component.ts looks like this:

import { Component, OnInit } from '@angular/core';

@Component({
  selector: 'app-header',
  templateUrl: './header.component.html',
  styleUrls: ['./header.component.css']
})
export class HeaderComponent implements OnInit {

  constructor() { }

  ngOnInit() {
  }
}

The modifications made are highlighted above.

Next, I included the following code in the header component to establish a reference to the SidebarComponent:

<app-sidebar #sidebarReference></app-sidebar>

With this setup, you can now easily utilize it within your template in header.component.ts

<button class="btn" (click)="sidebarReference.toggleSidebar()"><i class="fa fa-reorder"></i></button>

Answer 6

In order to address this issue, I began by removing the import of the sidebar in header.component.ts along with its constructor. The final version of my header.component.ts looks like this:

import { Component, OnInit } from '@angular/core';

@Component({
  selector: 'app-header',
  templateUrl: './header.component.html',
  styleUrls: ['./header.component.css']
})
export class HeaderComponent implements OnInit {

  constructor() { }

  ngOnInit() {
  }
}

The modifications made are highlighted above.

Next, I included the following code in the header component to establish a reference to the SidebarComponent:

<app-sidebar #sidebarReference></app-sidebar>

With this setup, you can now easily utilize it within your template in header.component.ts

<button class="btn" (click)="sidebarReference.toggleSidebar()"><i class="fa fa-reorder"></i></button>

Answer 7

Answer №4

From what I understand, it is not possible to inject a component into another component. If you need inter-component communication, you have a couple of options: 1. Utilize a service 2. Or utilize @Input or @Output constructs depending on the connection between the components.

Answer 8

From what I understand, it is not possible to inject a component into another component. If you need inter-component communication, you have a couple of options: 1. Utilize a service 2. Or utilize @Input or @Output constructs depending on the connection between the components.

Unable to call a component's method from a different component in Angular 7

Answer №1

Answer №2

Answer №3

Answer №4

Similar questions

Is it possible to execute an HTTP request using a functional resolver?

What exactly does "blocking and tackling" refer to in the Angular2 documentation?

The value is currently unset in the TypeScript language

Angular 6 - Unlocking the Secrets of Filtered Results

Steps for displaying a 404 page on a server-side rendered dynamic route following a client-side page transition

What is the reason behind permitting void functions in the left part of an assignment in Typescript?

What is the benefit of utilizing ngSubmit over just using a basic button and function?

retrieve document data from firestore using the service

Combine an array of objects that are dynamically created into a single object

Organize items within an array based on dual properties rather than a single one

What is the process for transitioning global reusable types to package types within turborepo?

Issue with retrieving the positions of two numbers in an array

Volar and vue-tsc are producing conflicting TypeScript error messages

Exploring the depths of useDispatch and dispatch in React-Redux

Guide on combining vendor CSS files in a React application using Webpack

Tips for implementing HTTP requests in Angular 2 without TypeScript

Struggling to integrate Docker compatibility into an established NextJS project, encountering the frustrating "stat app/.next/standalone: file does not exist" message

The issue with Angular 2's Parameterised router link component not fully refreshing

Tips for utilizing a ternary operator to set a className in an element

What might be the underlying reason for Chrome displaying a net::ERR_FAILED error when attempting to make a request from a Vue frontend to a C# API using Axios?