Bidirectional data binding is the process of transmitting data from HTML elements to variables in a TypeScript file

I'm attempting to transfer data from an HTML form to the variables (email and password) in the function doRegister() when the form is submitted. However, I am encountering errors related to two-way data binding.

Errors:

In HTML: Parser Error: Got interpolation ({{}}) where expression was expected at column 0 in [{{email}}=$event] in "path to the HTML document"

In TS file: Can't resolve all parameters for RegisterComponent in "path to the .ts file"

1. HTML FILE

<p class="lead">Already a member? Please <a routerLink="/login">log in</a> instead</p>
<form (submit)="onRegisterSubmit()">
<div role="alert" *ngIf="formError" class="alert">{{ formError }}</div>
      <p>
          <label>Email</label>
          <input type="text" [(ngModel)]="email" required>
      </p>
      <p>
          <label>Password:</label>
          <input type="password" [(ngModel)]="password" required>

      </p>
      <p>
          <button type="submit" >Submit</button>
      </p>
  </form>

2 .TS file

import { User, UserRegister } from './../user';

import { Component, OnInit } from '@angular/core';
import { NgModule }      from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';
import { Loc8rDataService } from '../loc8r-data.service';
import { Router } from '@angular/router';
import { AuthenticationService } from '../authentication.service';



@Component({
  selector: 'app-register',
  templateUrl: './register.component.html',
  styleUrls: ['./register.component.css']
})

    export class RegisterComponent implements OnInit {
    
      constructor(private Authentication: AuthenticationService) { }
    
      
      ngOnInit() {
      }
        
    
      formError: string ='';
    
        public onRegisterSubmit(): void {
    
        this.doRegister();
       
          }
    
        private doRegister(): void {
    
          let uEmail = '';
    let uPassword = '';
    const userreg: UserRegister = {email: uEmail, password: uPassword };
    
        this.Authentication.register(userreg)
        .catch((message: string) => this.formError = message);
    
        }
    
    }

Answer №1

The error message states that the identifier 'password' is not defined. This means that the component declaration, template variable declarations, and element references do not contain such a member.

This issue arises because the TS file cannot find the two variables. To resolve this problem, make sure to include the following code in your HTML file:

HTML file.

<p class="lead">Already a member? Please <a routerLink="/login">log in</a> instead</p>
    <form (submit)="onRegisterSubmit()">
    <div role="alert" *ngIf="formError" class="alert">{{ formError }}</div>
          <p>
              <label>Email</label>
              <input type="text" [(ngModel)]="email" required>
          </p>
          <p>
              <label>Password:</label>
              <input type="password" [(ngModel)]="password" required>
    
          </p>
          <p>
              <button type="submit" >Submit</button>
          </p>
      </form>

.TS file

import { User, UserRegister } from './../user';

import { Component, OnInit } from '@angular/core';
import { NgModule }      from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';
import { Loc8rDataService } from '../loc8r-data.service';
import { Router } from '@angular/router';
import { AuthenticationService } from '../authentication.service';



@Component({
  selector: 'app-register',
  templateUrl: './register.component.html',
  styleUrls: ['./register.component.css']
})

    export class RegisterComponent implements OnInit {
    
      constructor(private Authentication: AuthenticationService) { }
    
      
      ngOnInit() {
      }
      password:string='';
      email:string='';
        
    
      formError: string ='';
    
        public onRegisterSubmit(): void {
    
        this.doRegister();
       
          }
    
        private doRegister(): void {
    
          let uEmail = '';
    let uPassword = '';
    const userreg: UserRegister = {email: uEmail, password: uPassword };
    
        this.Authentication.register(userreg)
        .catch((message: string) => this.formError = message);
    
        }
    
    }

Answer №2

For more details, refer to the links provided below. It seems like there's an error in your syntax. Check it out:

https://angular.io/guide/two-way-binding

https://angular.io/guide/built-in-directives#ngModel

The use of braces is unnecessary.

 <input type="password" [(ngModel)]="{{password}}" required>

Instead, it should be:

 <input type="password" [(ngModel)]="password" required>

Make sure to declare any variables used in your HTML template as public fields in your .ts file, or else they won't be accessible in the HTML.

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