Ways to implement the disabled attribute in a child component and how to dynamically pass functions within it

Question

Ways to implement the disabled attribute in a child component and how to dynamically pass functions within it

I have an additional component for a button that needs to be incorporated in various other components containing forms. The button always stays the same, with consistent style formatting. The only variable is the function(s) that should be triggered upon clicking the button depending on the process.

For example, in user-login.html, I would trigger:

(click)="login(inputUserName.value, inputUserPass.value)"

, whereas in user-register.html, I would trigger: (click)="register(inputUserEmail.value)"

While attempting to implement this concept:

button-form.component.html:

<button mat-raised-button [disabled]="!form.valid" [color]="'primary'">
    <span>{{buttonText}}</span>
</button>

button-form.component.ts:

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

@Component({
  selector: 'app-button-form',
  templateUrl: './button-form.component.html'
})
export class ButtonFormComponent implements OnInit {
    @Input() buttonText: string;
    constructor() { }
    ngOnInit() {
    }
}

user-login.html:

<form #form="ngForm">
   ....
    <app-form-button [buttonText]="TextToShowOnButton"></app-form-button>
   ....
</form>

I encounter two challenges:

With regards to the disabled property, I receive
```
ERROR TypeError: Cannot read property 'valid' of undefined
```
. This error is understandable as the property form is not defined in button-form.component.ts, while the form exists in login.html as <form #form="ngForm">. I attempted using interpolation within property binding, but it did not resolve the issue.
I am struggling to dynamically pass the function to the button based on the form and the process.

I have researched this matter extensively but haven't discovered a suitable solution...

angular typescript

Answer 1

Answer №1

To ensure the button remains an isolated component and does not need knowledge of its surroundings, it is necessary to pass the form to the button, along with any desired behaviors via its inputs:

Thus:

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

@Component({
  selector: 'app-button-form',
  templateUrl: './button-form.component.html'
})
export class ButtonFormComponent implements OnInit {
    @Input() buttonText: string;
    @Input() form: NgForm;
    @Output() click: EventEmitter<Event> = new EventEmitter();
    constructor() { }
    ngOnInit() {
    }

    onClick(event: Event): void {
        this.click.emit(event);
    }
}

Next, in the template:

<button mat-raised-button [disabled]="!form.valid" [color]="'primary'" (click)="onClick($event)">
    <span>{{buttonText}}</span>
</button>

Lastly, within the form where you wish to utilize it:

<form #form="ngForm">
   ....
    <app-form-button [form]="form" [buttonText]="TextToShowOnButton" (click)="register(...)"></app-form-button>
   ....
</form>

In essence, a new input for the form and an @Output are added to relay the button's click event upwards.

Trust this proves beneficial to you.

Answer 2

To ensure the button remains an isolated component and does not need knowledge of its surroundings, it is necessary to pass the form to the button, along with any desired behaviors via its inputs:

Thus:

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

@Component({
  selector: 'app-button-form',
  templateUrl: './button-form.component.html'
})
export class ButtonFormComponent implements OnInit {
    @Input() buttonText: string;
    @Input() form: NgForm;
    @Output() click: EventEmitter<Event> = new EventEmitter();
    constructor() { }
    ngOnInit() {
    }

    onClick(event: Event): void {
        this.click.emit(event);
    }
}

Next, in the template:

<button mat-raised-button [disabled]="!form.valid" [color]="'primary'" (click)="onClick($event)">
    <span>{{buttonText}}</span>
</button>

Lastly, within the form where you wish to utilize it:

<form #form="ngForm">
   ....
    <app-form-button [form]="form" [buttonText]="TextToShowOnButton" (click)="register(...)"></app-form-button>
   ....
</form>

In essence, a new input for the form and an @Output are added to relay the button's click event upwards.

Trust this proves beneficial to you.

Answer 3

Answer №2

To enhance your button-form.component, you can add a new input property called @Input() isClickable: boolean. Pass this property from the parent component like so:

<app-form-button [isClickable]="form.valid" [buttonText]="CustomButtonText"></app-form-button>

. Then, utilize it in your HTML code.

<button mat-raised-button [disabled]="!isClickable" [color]="'primary'">
    <span>{{buttonText}}</span>
</button>

Answer 4

To enhance your button-form.component, you can add a new input property called @Input() isClickable: boolean. Pass this property from the parent component like so:

<app-form-button [isClickable]="form.valid" [buttonText]="CustomButtonText"></app-form-button>

. Then, utilize it in your HTML code.

<button mat-raised-button [disabled]="!isClickable" [color]="'primary'">
    <span>{{buttonText}}</span>
</button>

Answer 5

Answer №3

I'm facing a challenge in dynamically passing a function to the Button component based on the form and process.

Instead of directly passing a function, it's recommended to use an Output event emitter and register it in the hosting component.

<form #form="ngForm">
   ....
    <app-form-button (onSomething)="foo($event)"...></app-form-button>
   ....
</form>

Answer 6

I'm facing a challenge in dynamically passing a function to the Button component based on the form and process.

Instead of directly passing a function, it's recommended to use an Output event emitter and register it in the hosting component.

<form #form="ngForm">
   ....
    <app-form-button (onSomething)="foo($event)"...></app-form-button>
   ....
</form>

Answer 7

Answer №4

To accomplish this task, follow these steps:

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

@Component({
  selector: 'app-button-form',
  templateUrl: './button-form.component.html'
})
export class ButtonFormComponent implements OnInit {
    @Input() buttonText: string;
    @Input() disabled: boolean;
    @Output() buttonClicked: EventEmitter<any> = new EventEmitter();
    constructor() { }
    ngOnInit() {
    }
}

<form #form="ngForm">
   ....
    <app-form-button [buttonText]="TextToShowOnButton" [disabled]="!form.valid" 
(buttonClicked)="myFunction"></app-form-button>

This approach not only allows you to easily achieve the desired outcome, but also enhances the reusability of the button component by abstracting it (Instead of having the button component handle form validation and click events internally, which would limit its usability to forms only).

Answer 8

To accomplish this task, follow these steps:

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

@Component({
  selector: 'app-button-form',
  templateUrl: './button-form.component.html'
})
export class ButtonFormComponent implements OnInit {
    @Input() buttonText: string;
    @Input() disabled: boolean;
    @Output() buttonClicked: EventEmitter<any> = new EventEmitter();
    constructor() { }
    ngOnInit() {
    }
}

<form #form="ngForm">
   ....
    <app-form-button [buttonText]="TextToShowOnButton" [disabled]="!form.valid" 
(buttonClicked)="myFunction"></app-form-button>

This approach not only allows you to easily achieve the desired outcome, but also enhances the reusability of the button component by abstracting it (Instead of having the button component handle form validation and click events internally, which would limit its usability to forms only).

Ways to implement the disabled attribute in a child component and how to dynamically pass functions within it

Answer №1

Answer №2

Answer №3

Answer №4

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