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Answer:65 #1464

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5113d8b
feat(Answer:65): refactor to use signal form
phhien203 Mar 24, 2026
560ad55
feat(Answer:65): use linkedSignal to set value of userModel
phhien203 Mar 25, 2026
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127 changes: 69 additions & 58 deletions apps/forms/65-signal-form-edition/src/app/user-form.component.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -4,21 +4,18 @@ import {
effect,
inject,
input,
signal,
} from '@angular/core';
import { rxResource } from '@angular/core/rxjs-interop';
import {
FormControl,
FormGroup,
ReactiveFormsModule,
Validators,
} from '@angular/forms';
import { form, FormField, min, required, submit } from '@angular/forms/signals';
import { Router } from '@angular/router';
import { of } from 'rxjs';
import { lastValueFrom, of } from 'rxjs';
import { FakeBackendService } from './fake-backend.service';
import { User } from './user.model';

@Component({
selector: 'app-user-form',
imports: [ReactiveFormsModule],
imports: [FormField],
template: `
<div class="rounded-lg border border-gray-200 bg-white p-6 shadow-sm">
<h2 class="mb-4 text-xl font-semibold text-gray-800">
Expand All @@ -30,7 +27,7 @@ import { FakeBackendService } from './fake-backend.service';
class="h-8 w-8 animate-spin rounded-full border-4 border-indigo-500 border-t-transparent"></div>
</div>
} @else {
<form [formGroup]="userForm" (ngSubmit)="onSubmit()" class="space-y-4">
<form (submit)="onSubmit($event)" class="space-y-4">
<div>
<label
for="firstname"
Expand All @@ -40,15 +37,18 @@ import { FakeBackendService } from './fake-backend.service';
<input
id="firstname"
type="text"
formControlName="firstname"
class="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm" />
class="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:ring-indigo-500 focus:outline-none sm:text-sm"
[formField]="userSignalForm.firstname" />
@if (
userForm.get('firstname')?.invalid &&
userForm.get('firstname')?.touched
userSignalForm.firstname().invalid() &&
userSignalForm.firstname().touched()
) {
<p class="mt-1 text-xs text-red-500">Firstname is required</p>
@for (error of userSignalForm.firstname().errors(); track error) {
<p class="mt-1 text-xs text-red-500">{{ error.message }}</p>
}
}
</div>

<div>
<label
for="lastname"
Expand All @@ -58,49 +58,59 @@ import { FakeBackendService } from './fake-backend.service';
<input
id="lastname"
type="text"
formControlName="lastname"
class="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm" />
class="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:ring-indigo-500 focus:outline-none sm:text-sm"
[formField]="userSignalForm.lastname" />
@if (
userForm.get('lastname')?.invalid &&
userForm.get('lastname')?.touched
userSignalForm.lastname().invalid() &&
userSignalForm.lastname().touched()
) {
<p class="mt-1 text-xs text-red-500">Lastname is required</p>
@for (error of userSignalForm.lastname().errors(); track error) {
<p class="mt-1 text-xs text-red-500">{{ error.message }}</p>
}
}
</div>

<div>
<label for="age" class="block text-sm font-medium text-gray-700">
Age
</label>
<input
id="age"
type="number"
formControlName="age"
class="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm" />
@if (userForm.get('age')?.invalid && userForm.get('age')?.touched) {
<p class="mt-1 text-xs text-red-500">Age must be positive</p>
class="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:ring-indigo-500 focus:outline-none sm:text-sm"
[formField]="userSignalForm.age" />
@if (
userSignalForm.age().invalid() && userSignalForm.age().touched()
) {
@for (error of userSignalForm.age().errors(); track error) {
<p class="mt-1 text-xs text-red-500">{{ error.message }}</p>
}
}
</div>

<div>
<label for="grade" class="block text-sm font-medium text-gray-700">
Grade
</label>
<input
id="grade"
type="number"
formControlName="grade"
class="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm" />
class="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:ring-indigo-500 focus:outline-none sm:text-sm"
[formField]="userSignalForm.grade" />
</div>

<div class="flex justify-end space-x-3 pt-4">
<button
type="button"
(click)="onCancel()"
class="rounded-md border border-gray-300 bg-white px-4 py-2 text-sm font-medium text-gray-700 hover:bg-gray-50 focus:outline-none focus:ring-2 focus:ring-indigo-500 focus:ring-offset-2">
class="rounded-md border border-gray-300 bg-white px-4 py-2 text-sm font-medium text-gray-700 hover:bg-gray-50 focus:ring-2 focus:ring-indigo-500 focus:ring-offset-2 focus:outline-none">
Cancel
</button>

<button
type="submit"
[disabled]="userForm.invalid"
class="rounded-md border border-transparent bg-indigo-600 px-4 py-2 text-sm font-medium text-white shadow-sm hover:bg-indigo-700 focus:outline-none focus:ring-2 focus:ring-indigo-500 focus:ring-offset-2 disabled:opacity-50">
[disabled]="userSignalForm().invalid()"
class="rounded-md border border-transparent bg-indigo-600 px-4 py-2 text-sm font-medium text-white shadow-sm hover:bg-indigo-700 focus:ring-2 focus:ring-indigo-500 focus:ring-offset-2 focus:outline-none disabled:opacity-50">
{{ id() ? 'Update' : 'Add' }}
</button>
</div>
Expand All @@ -124,50 +134,51 @@ export class UserFormComponent {
defaultValue: undefined,
});

userForm = new FormGroup({
firstname: new FormControl('', {
nonNullable: true,
validators: [Validators.required],
}),
lastname: new FormControl('', {
nonNullable: true,
validators: [Validators.required],
}),
age: new FormControl(0, {
nonNullable: true,
validators: [Validators.required, Validators.min(0)],
}),
grade: new FormControl(0, {
nonNullable: true,
validators: [Validators.required],
}),
userModel = signal<Omit<User, 'id'>>({
firstname: '',
lastname: '',
age: 0,
grade: 0,
});
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@tomalaforge tomalaforge Mar 26, 2026

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yes a lot nicer, isn't it

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@phhien203 phhien203 Mar 26, 2026

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Yep, that's right!


userSignalForm = form(this.userModel, (schemePath) => {
required(schemePath.firstname, { message: 'Firstname is required' });
required(schemePath.lastname, { message: 'Lastname is required' });
required(schemePath.age);
min(schemePath.age, 0, { message: 'Age must be positive' });
required(schemePath.grade);
});

constructor() {
effect(() => {
const userValue = this.userResource.value();
if (userValue) {
this.userForm.patchValue(userValue);
this.userModel.set(userValue);
} else {
this.userForm.reset({ firstname: '', lastname: '', age: 0, grade: 0 });
this.userModel.set({ firstname: '', lastname: '', age: 0, grade: 0 });
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@tomalaforge tomalaforge Mar 25, 2026

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I created this challenge because you can avoid effect thanks to signal forms.
You should look at linkedSignals.

Everything should happen in the creation of userModel

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@phhien203 phhien203 Mar 25, 2026

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Thanks! I updated the code to use linkedSignal.

}
});
}

onSubmit(): void {
if (this.userForm.valid) {
onSubmit(event: Event): void {
event.preventDefault();

submit(this.userSignalForm, async () => {
const userValue = this.userResource.value();
const obs = userValue
? this.backend.updateUser({
...this.userForm.getRawValue(),

if (userValue) {
await lastValueFrom(
this.backend.updateUser({
...this.userModel(),
id: userValue.id,
})
: this.backend.addUser(this.userForm.getRawValue());
}),
);
} else {
await lastValueFrom(this.backend.addUser(this.userModel()));
}

obs.subscribe(() => {
this.router.navigate(['/']);
});
}
this.router.navigate(['/']);
});
}

onCancel(): void {
Expand Down
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