Challenges with deploying Angular applications and dealing with undefined properties within Angular code

Currently, I have successfully added new products to the database with all the desired properties. However, I am facing errors that are preventing me from deploying the application for production. Fixing these errors causes further issues where I cannot add new items to the database.

Here are the errors before attempting to fix them:

ERROR in src\app\admin\product-form\product-form.component.html(10,11): : Property 'title' does not exist on type '{}'.
src\app\admin\product-form\product-form.component.html(27,13): : Property 'price' does not exist on type '{}'.
...

In the component, changing

  product = {};

to

product: Product;

results in

Error: Cannot read property 'title' of undefined

and using

product: Product = {};

gives the error

  ERROR in src/app/admin/product-form/product-form.component.ts(15,5): error TS2322: Type '{}' is not assignable to type 'Product'.
  Property '$key' is missing in type '{}'.

The component code:

 import { Component, OnInit } from '@angular/core';
...

The template code:

<div class="row">
    <div class="col-md-6">
        ...
    </div>

    <div class="col-md-6">
        <product-card [product]="product"
            [show-actions]="false"></product-card>
    </div>
</div>

The definition of the 'Product' interface:

export interface Product {
  $key: string;
  title: string;
  price: number;
  category: string;
  imageUrl: string;
}

Answer №1

To avoid errors when rendering your HTML, make sure to include default values in your variable declaration or assign them within the constructor. This is important because the HTML will expect a 'title' key in your product variable. You can then update these default values with actual data as needed. Here's an example:

product: Product = {
    $key: '',
    title: '',
    price: null,
    category: '',
    imageUrl: ''
};

I hope this explanation helps you! :)

Answer №2

I propose a modification:

product = {};

To

product: Product;

Afterwards, utilize the ? operator within your template to prevent access to undefined values:

<div class="row" *ngIf="product?.$key">

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