Introduction to Forms in Angular: Template-Driven Forms

Forms are essential in modern front-end applications, handling user interactions daily, from logins and searches to bookings and to-do lists. While some forms are simple, others can be complex, spanning multiple pages. This tutorial explores Angular's template-driven forms approach for building them. Regardless of your chosen method, a robust form library should provide:

• Two-way data binding: Keeps input values synchronized with component state.
• Form state tracking: Visually indicates form validity (e.g., using red borders for errors).
• Error handling: Clearly displays validation errors.
• Conditional enabling/disabling: Controls form sections based on validation.

Angular's Form Strategies

Angular offers two powerful form-building strategies: template-driven forms and model-driven (reactive) forms. Both utilize the FormsModule.

Building a Signup Form: A Step-by-Step Guide

This example demonstrates a simple signup form using template-driven forms.

1. User Model: Define a User class (or interface) to represent form data:

   export class User {
       constructor(
           public id: number,
           public email: string,
           public pwd: string,
           public confirmPwd: string,
           public gender: string,
           public terms: boolean
       ) { }
   }

2. Component Setup: Create the necessary components and layout for the signup form.

3. Two-Way Binding with ngModel: Use ngModel for two-way data binding between the form inputs and the User object in your component.

4. Form Submission: Handle form submission using the (ngSubmit) event.

5. Component Logic: In your component's TypeScript file, handle form submission:

   onSubmit({ value, valid }: NgForm) {
       console.log(this.user.email);
       console.log("valid: " + valid);
   }

6. Complete Example: A complete, runnable example is available on GitHub (link omitted for brevity). This example includes styling using Bootstrap.

Conclusion

This tutorial covers template-driven forms in Angular. While simple and easy to use for smaller forms, this approach can become less manageable for complex forms. The next tutorial will explore model-driven forms as a more scalable alternative.

This post incorporates contributions from Esther Vaati, a software developer and writer for Envato Tuts .

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