How to call parent function in child button

Question

Suppose I have a component called ButtonComponent which will be used in various places in the application, so I make is as generic as possible, like so:

button.component.ts

import { Component, ViewEncapsulation, Input, Output, EventEmitter } from '@angular/core';
import { FormGroup } from '@angular/forms';

@Component({
  selector: 'app-button',
  templateUrl: './button.component.html',
  styleUrls: ['./button.component.scss'],
  encapsulation: ViewEncapsulation.None
})
export class ButtonComponent{

  @Input() group: FormGroup;
  @Input() type: string;
  @Input() description: string;
  @Input() class: string;
  @Input() callFunction: Function;
}

button.component.html

<div [formGroup]="group">
  <button type="{{ type }}" class="{{ class }}" (click)="callFunction()">{{ description }}</button>
</div>

Now my button is completely customizable (in theory). I am now going to import it to a login component which has a function called login(). I want my button instance to run this specific function when I click it:

login.component.ts

//imports

/**
* This component is rendered at the start of application, it provides the UI
* & functionality for the login page.
*/
@Component({
  selector: 'app-login',
  templateUrl: './login.component.html',
  styleUrls: ['./login.component.scss']
})

/**
* This class is used to build a login form along with initialization of validators
* as well as authenticate the user, and reroute upon success
*/
export class LoginComponent implements OnInit, AfterContentInit{

  @ViewChild('login', { read: ViewContainerRef }) login_button;


  /**
  * This property initializes the formGroup element.
  */
  userForm: FormGroup;

  /**
  * The constructor initializes Router, FormBuilder, OauthService, LoggerService, ToastrService
  * & TranslatePipe in the component.
  */
  constructor(//initializations
  ) { }

  /**
  * This is the hook called on the initialization of the component, it initializes
  * the form.
  */
  ngOnInit() {
    this.buildForm();
  }



  /**
   * This method initialized the the formGroup element. Its properties and the validators.
   *
   * @method buildForm
   * @return
   */
  buildForm() { 
    // validations
  });
  }

   /**
   * This method returns the values of the form controls.
   *
   * @return
   */
  get form() { return this.userForm.controls; }

   /**
   * This method is triggered on success, it reroutes the user to main page.
   *
   * @return
   */
  onSuccess() {
    let result = this.translate.transform("pages[login_page][responses][success]");
    this.logger.info(result);
    this.toastr.success(result);
    this.router.navigate(['main']);
  }

   /**
   * This method is triggered when user clicks log-in, it calls the aunthenication method
   * from oauth service.
   *
   * @return
   */
  login() {
    this.oauth.authenticateUser(this.form.username.value, this.form.password.value, this.onSuccess.bind(this));
  }

  ngAfterContentInit() { //here I build my login button instance after init
    this.buildLoginButton();
  }


  /**
  * This function builds the login button, imports the ButtonComponent
  *
  */
  buildLoginButton(){
    let data = {
      type: "button",
      class: "btn btn-primary px-4",
      description: this.translate.transform("pages[login_page][login_form][buttons][login]"),
      function: "login",
      group: this.userForm
      }
    const inputFactory = this.resolver.resolveComponentFactory(ButtonComponent);
    const loginButton = this.login_button.createComponent(inputFactory);
    loginButton.instance.group = data.group;
    loginButton.instance.type = data.type;
    loginButton.instance.class = data.class;
    loginButton.instance.description = data.description;
    loginButton.instance.callFunction = function(){ //I call parent function using a static method
      LoginComponent.executeMethod(data.function);
    }
  }


  static executeMethod(someMethod){ //for my login button this should return this.login()
    eval("this."+someMethod+"()");
  }

}

To make the button instance visible I add the reference into my login template like this:

<div #login></div>

Now my button is visible, great! But now when i click the button:

ERROR TypeError: this.login is not a function at eval (eval at push../src/app/views/login/login.component.ts.LoginComponent.executeMethod (login.component.ts:225), :1:6) at Function.push../src/app/views/login/login.component.ts.LoginComponent.executeMethod (login.component.ts:225) at ButtonComponent.loginButton.instance.callFunction (login.component.ts:179) at Object.eval [as handleEvent] (ButtonComponent.html:2) at handleEvent (core.js:10251) at callWithDebugContext (core.js:11344) at Object.debugHandleEvent [as handleEvent] (core.js:11047) at dispatchEvent (core.js:7710) at core.js:8154 at HTMLButtonElement. (platform-browser.js:988)

How do I make my button run the function in the parent component instead of looking for the function within itself? I don't want to change a lot in the ButtonComponent that would make it less generic as I have to make other buttons as well that would probably run other functions.

There was a solution that stated using EventEmitter for this, but I am unsure how this would work given how I am importing the button into the login component, both the ts and the html

Edit the complete login.component.html:

<div class="app-body">
  <main class="main d-flex align-items-center">
    <div class="container center">
      <div class="row">
        <div class="col-md-8 mx-auto">
          <div class="card-group">
            <div class="card p-4">
              <div class="card-body">
                <form [formGroup]="userForm" (submit)="login()">
                  <h1>{{ 'pages[login_page][login_form][labels][login]' | translate }}</h1>
                  <p class="text-muted">{{ 'pages[login_page][login_form][labels][sign_in]' | translate }}</p>
                  <div class="input-group mb-3">
                    <div class="input-group-prepend">
                      <span class="input-group-text"><i class="icon-user"></i></span>
                    </div>
                    <div #username> </div>
                  </div>
                  <div class="input-group mb-4">
                    <div class="input-group-prepend">
                      <span class="input-group-text"><i class="icon-lock"></i></span>
                    </div>
                    <div #password> </div>
                  </div>
                  <div class="row">
                    <div class="col-6">
                      <div #login></div>
                    <!--  <button type="button" class="btn btn-primary px-4" (click)="login()">{{ 'pages[login_page][login_form][buttons][login]' | translate }}</button> -->
                    </div>
                    <div class="col-6 text-right">
                      <div #forgot></div>
                    <!--  <button type="button" class="btn btn-link px-0">{{ 'pages[login_page][login_form][urls][forgot_password]' | translate }}</button>-->
                    </div>
                  </div>
                </form>
              </div>
            </div>
            <div class="card text-white bg-primary py-5 d-md-down-none" style="width:44%">
              <div class="card-body text-center">
                <div>
                  <h2>{{ 'pages[login_page][sign_up_panel][labels][sign_up]' | translate }}</h2>
                  <p>{{ 'pages[login_page][sign_up_panel][labels][new_account]' | translate }}</p>
                  <div #signUp></div>
                <!--  <button type="button" class="btn btn-primary active mt-3">{{ 'pages[login_page][sign_up_panel][buttons][register]' | translate }}</button> -->
                </div>
              </div>
            </div>
          </div>
        </div>
      </div>
    </div>
  </main>
</div>

Answer 1

Add this code in button.component.ts

@Output() clickFunctionCalled = new EventEmitter<any>();
callFunction() {
    this.clickFunctionCalled.emit();   
  }

No change in button.template.html

Add this code where you use app-button component in html

<app-button  (clickFunctionCalled)="callCustomClickFunction($event)"></app-button>

Add this in login.component.ts

callCustomClickFunction() {
   console.log("custom click called in login");
   this.login();
}

Basically, emit the click event from the child component. Catch the event in the parent component and call the desired function of the parent component. You can also directly call the parent component's function like this

<app-button  (clickFunctionCalled)="login($event)"></app-button>

As you are using dynamic component creator for creating the button component, you need to do something like this, for binding output event

loginButton.instance.clickFunctionCalled.subscribe(data => {
    console.log(data);
});