Associate a fresh entity with an Angular form rather than individual attributes

My interface is quite simple:

(models.ts)

export interface User{
Id : number;
FirstName : string;
LastName : string;
Email: string;
PhoneNumber: string;
}

As for my form, it's also pretty straightforward:

(app.component.html)

 <fieldset class='form-group' >
  <h2>Create New User</h2>
  <label>First Name: <input type="text" [(ngModel)]='FirstName'></label><br>
  <label>Last Name: <input type="text" [(ngModel)]='LastName'></label><br>
  <label>Phone number: <input type="phone"[(ngModel)]='PhoneNumber'></label><br>
  <label>Email Address: <input type="email" [(ngModel)]='Email'></label><br>
<button (click)="createNewUser()">Create User</button>
</fieldset>

I currently bind my data to simple strings in order to create an object based on them. This method works but feels a bit cluttered. I was considering creating a new empty object and then assigning the values directly to it like this:

(app.component.ts)

 userToCreate: User;

(app.component.html)

    <label>First Name: <input type="text" [(ngModel)]='userToCreate.FirstName'></label><br>

However, when attempting this approach, TypeScript throws an error message which reads:

Cannot read property 'FirstName' of undefined

What am I doing wrong here, or is this not feasible?

Answer №1

The issue arises from the fact that the variable userToCreate is currently set to undefined, resulting in none of the properties being bound.

To address this, you can either bind to individual properties within your component and construct the user object within the createNewUser function, or initialize userToCreate with an empty object as shown below:

userToCreate: User = {} as User;

The use of type assertion (or cast) is necessary because simply using {} does not explicitly define all the required properties of the User interface.

Answer №2

Have you considered implementing reactive forms with the form builder? This approach would allow you to:

  1. Enhance manipulation of your inputs;
  2. Integrate validation seamlessly;
  3. Utilize NgOnSubmit functionality on your button;

Check out the Reactive Forms documentation for more information.

Furthermore, by leveraging typings and default values in the form builder, you may resolve any issues related to undefined objects.

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