Introduction to two methods of Angular form validation

For front-end developers, forms are very important. They are responsible for the interaction between users and programs. It carries part of the data verification function to reduce the pressure on the server. This article introduces two methods of Angular form validation.

Template-driven validation

In order to add validation to the template-driven form, you need to add some validation attributes. Here we take the user login interface as an example

1: Create a new project

Go to the working path, runng new validateCreate an angular project, and then open it with vscode

Two: Modify the app.component.html template file

Create a form with two input boxes for username and password. Next, These two input boxes are verified

app.component.html

<br><br>
<p>
    </p><p>
        </p><p>
        </p>
        <p>
      </p><h1>Login</h1>
            

The styles used in the code are all css styles provided in Bootstrap 4. Readers can download them from its official website.
The final style is as follows:

3: Add verification
First in app. In module.ts, add the FormsModule module and add it to the imports array

app.module.ts

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';

import { AppComponent } from './app.component';
import { FormsModule } from '@angular/forms';
@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    FormsModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

Then add verification in the template page

Add verified app.component.html

<br><br>
<p>
    </p><p>
        </p><p>
        </p>
        <p>
      </p><h1>Login</h1>
            

The final effect is as follows:

Four: Notes
The name attribute must be added to the Input tag, and #name cannot be the same as the attribute name of class in ts, as shown in the figure

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';

import { AppComponent } from './app.component';
import { FormsModule, ReactiveFormsModule } from '@angular/forms';
import { StudentComponent } from './student/student.component';

@NgModule({
   declarations: [
      AppComponent,
      StudentComponent
   ],
   imports: [
      BrowserModule,
      FormsModule,
      ReactiveFormsModule
   ],
   providers: [],
   bootstrap: [
      AppComponent
   ]
})
export class AppModule { }

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