Exploring My Angular Component
import { Router, ActivatedRoute } from '@angular/router';
import { Component, OnInit } from '@angular/core';
import { CategoriesService } from 'src/app/categories.service';
import { ProductService } from 'src/app/product.service';
import 'rxjs/add/operator/take';
import { Product } from './product';
import { take } from 'rxjs/operators';
@Component({
selector: 'app-product-forms',
templateUrl: './product-forms.component.html',
styleUrls: ['./product-forms.component.css']
})
export class ProductFormsComponent implements OnInit {
categories$;
product: any = {};
constructor(categoryservice: CategoriesService , private productservice: ProductService , private router: Router,
private route: ActivatedRoute) {
this.categories$ = categoryservice.getcategories();
let id = this.route.snapshot.paramMap.get('id');
if (id) { this.productservice.get(id).valueChanges().pipe(take(1))
.subscribe(p => this.product = p);
}
}
save(product) {
this.productservice.create(product);
this.router.navigate(['/admin/products']);
}
ngOnInit() {
}
}
Glimpse into My HTML Structure
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title >Product Form</title>
</head>
<div class="row">
<div class="col-md-6">
<form #f="ngForm" (ngSubmit)="save(f.value)">
<div class="form-group">
<label for="title">Title</label>
<input #title="ngModel" [(ngModel)]="product.title" name="title" id="title" type="text" class="form-control" required>
<div class="alert alert-danger" *ngIf="title.touched && title.invalid">
Title is required
</div>
</div>
<div class="form-group">
<label for="price">Price</label>
<div class="input-group-prepend">
<span class="input-group-text">$</span>
<input #price="ngModel" [(ngModel)]="product.price" name="price" id="price" type="number" class="form-control" required [min]="0">
</div>
<div class="alert alert-danger" *ngIf="price.touched && price.invalid">
<div *ngIf="price.errors.required">Price is required</div>
<div *ngIf="price.errors.min">Price must be 0 or higher than zero</div>
</div>
</div>
<div class="form-group">
<label for="category">Category</label>
<select #category="ngModel" [(ngModel)]="product.category" name="category" id="category" class="form-control" required>
<option value=""></option>
<option *ngFor="let c of categories$ | async" [value]="c.$key">
{{ c.name }}
</option>
</select>
<div class="alert alert-danger" *ngIf="category.touched && category.invalid">
Category is required
</div>
</div>
<div class="form-group">
<label for="imageurl">Image Url</label>
<input #imageUrl="ngModel" [(ngModel)]="product.imageUrl" name="imageUrl" id="imageurl" type="text" class="form-control" required url>
<div class="alert alert-danger" *ngIf="imageUrl.touched && imageUrl.invalid">
<div *ngIf="imageUrl.errors.required">ImageUrl is required</div>
<div *ngIf="imageUrl.errors.url">ImageUrl is required</div>
</div>
</div>
<button class="btn btn-primary">Save</button>
</form>
</div>
<div class="col-md-6">
<div class="card" style="width: 18rem;">
<img [src]="product.imageUrl" class="card-img-top" alt="..." *ngIf="product.imageUrl">
<div class="card-body">
<h5 class="card-title"> {{product.title}} </h5>
<p class="card-text"> {{product.price | currency:'USD':true}} </p>
</div>
</div>
</div>
</div>
A Peek at My Product Service Implementation:
import { Product } from './admin/product-forms/product';
import { AngularFireDatabase } from '@angular/fire/database';
import { Injectable } from '@angular/core';
import { Observable } from 'rxjs';
@Injectable({
providedIn: 'root'
})
export class ProductService {
constructor(private db: AngularFireDatabase) { }
create(product) {
return this.db.list('/products').push(product);
}
getAll() {
return this.db.list('/products');
}
get(productId): Observable<any> {
return this.db.object('/products' + productId).valueChanges();
}
}
An Error Crops Up Here: "
if (id) {
this.productservice
.get(id)
.valueChanges()
.pipe(take(1))
.subscribe(p => this.product = p);
When I Remove valueChanges(), Another Hurdle Appears: Whenever I interact with an input field in my deployed project, the following error surfaces...
"TypeError: Cannot read property 'title' of undefined".
If anyone has insights on how to resolve this issue, your assistance would be greatly appreciated. Thank you!