What is the best way to enforce input requirements in Typescript?

Question

What is the best way to enforce input requirements in Typescript?

I am currently facing an issue with two required inputs that need to be filled in order to enable the "Add" button functionality. I have considered using *ngIf to control the visibility of the button based on input values, but it seems to not be working. Can anyone point me in the right direction?

<input
    #neueEintragBeschreibung
    placeholder="Enter description"
    class="lg-text-input"
  />

  <input
    #neuesEintragFaelligkeitsdatum
    placeholder="Enter due date"
    class="lg-text-input"
  />

  <div *ngIf="neueEintragBeschreibung.value">
  <button class="btn-primary" (click)="addEintrag(neueEintragBeschreibung.value, neuesEintragFaelligkeitsdatum.value)">
    Add</button>
  </div>

angular typescript

Answer 1

Answer №1

If you want to retrieve the value of an input, it's best practice to utilize the forms API instead of directly accessing input.value. Here's an example:

<form #form="ngForm" (ngSubmit)="handleSubmit(form)">
  <input type="text" required name="myField" ngModel />

  <ng-container *ngIf="form.valid">
    <button type="submit">Add</button>
  </ng-container>
</form>

handleSubmit(form: NgForm) {
  console.log(`You entered: ${form.value.myField}`);
}

In this code snippet:

A form is created with a single field named "myField".
The field "myField" is made mandatory by utilizing the required attribute.
The "Add" button is only displayed when the form is valid. As the form mandates a required field, it will be considered valid once the user fills in this field.

Don't forget to include FormsModule in your module's imports for this functionality.

Answer 2

If you want to retrieve the value of an input, it's best practice to utilize the forms API instead of directly accessing input.value. Here's an example:

<form #form="ngForm" (ngSubmit)="handleSubmit(form)">
  <input type="text" required name="myField" ngModel />

  <ng-container *ngIf="form.valid">
    <button type="submit">Add</button>
  </ng-container>
</form>

handleSubmit(form: NgForm) {
  console.log(`You entered: ${form.value.myField}`);
}

In this code snippet:

A form is created with a single field named "myField".
The field "myField" is made mandatory by utilizing the required attribute.
The "Add" button is only displayed when the form is valid. As the form mandates a required field, it will be considered valid once the user fills in this field.

Don't forget to include FormsModule in your module's imports for this functionality.

Answer 3

Answer №2

To discover the solution, visit this link: https://www.digitalocean.com/community/tutorials/angular-reactive-forms-introduction

stackblitz:*https://stackblitz.com/edit/angular-ivy-im2nap?*file=src/app/app.module.ts

Utilize Angular Forms and denote the field as mandatory using a validator rule:

HTML

<form [formGroup]="myForm" (ngSubmit)="onSubmit(myForm)">
  <div>
    <label>
      Name:
      <input formControlName="name" placeholder="Your name">
    </label>
    <div *ngIf="myForm.get('name').invalid && (myForm.get('name').dirty || myForm.get('name').touched)">
      Please provide a name.
    </div>
  </div>
  <button type="submit" [disabled]="myForm.invalid">Send</button>
</form>

In your component, ensure to import the following:

import { FormBuilder, FormGroup, Validators } from '@angular/forms';

Additionally:

myForm: FormGroup;

  constructor(private fb: FormBuilder) {}

  ngOnInit() {
    this.myForm = this.fb.group({
      name: ['Sammy', Validators.required],
    });
  }

  onSubmit(form: FormGroup) {
    console.log('Valid?', form.valid); // true or false
    console.log('Name', form.value.name);
  }

Answer 4

To discover the solution, visit this link: https://www.digitalocean.com/community/tutorials/angular-reactive-forms-introduction

stackblitz:*https://stackblitz.com/edit/angular-ivy-im2nap?*file=src/app/app.module.ts

Utilize Angular Forms and denote the field as mandatory using a validator rule:

HTML

<form [formGroup]="myForm" (ngSubmit)="onSubmit(myForm)">
  <div>
    <label>
      Name:
      <input formControlName="name" placeholder="Your name">
    </label>
    <div *ngIf="myForm.get('name').invalid && (myForm.get('name').dirty || myForm.get('name').touched)">
      Please provide a name.
    </div>
  </div>
  <button type="submit" [disabled]="myForm.invalid">Send</button>
</form>

In your component, ensure to import the following:

import { FormBuilder, FormGroup, Validators } from '@angular/forms';

Additionally:

myForm: FormGroup;

  constructor(private fb: FormBuilder) {}

  ngOnInit() {
    this.myForm = this.fb.group({
      name: ['Sammy', Validators.required],
    });
  }

  onSubmit(form: FormGroup) {
    console.log('Valid?', form.valid); // true or false
    console.log('Name', form.value.name);
  }

What is the best way to enforce input requirements in Typescript?

Answer №1

Answer №2

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