Building TypeScript Model Classes

Greetings! As a newcomer to TypeScript with a background in both C# and JavaScript, I am on a quest to create class models resembling those found in C#.

Here's my attempt so far:

export class DonutChartModel {
    dimension: number;
    innerRadius: number;
    backgroundClass: string;
    backgroundOpacity: number;
}

I anticipated that this would produce a JavaScript model with the declared properties exposed. However, it only generates a function DonutChartModel without any declared properties.

Upon consulting the documentation, I discovered that in order to expose the properties, I must include a constructor and initialize the properties within it. While this approach may be functional, it becomes cumbersome when dealing with numerous properties per model, impacting readability as well.

I am hopeful that there is an alternative method to achieve this without having to pass constructor parameters:

var model = new DonutChartModel();
model.dimension = 5
model.innerRadius = 20
....

Is there a way to accomplish this in TypeScript?

Answer №1

Your goal seems to be establishing a structure for a model. While using a class in C# is appropriate for this purpose, in TypeScript it is recommended to create either a type or an interface.

Below are examples of both approaches (with simplified properties)

Type

type DonutChartModel = {
    dimension: number;
    innerRadius: number;
};
var donut: DonutChartModel = {
    dimension: 1,
    innerRadius: 2
};

Interface

interface IDonutChartModel {
    dimension: number;
    innerRadius: number;
}
var donut: IDonutChartModel = {
    dimension: 1,
    innerRadius: 2
};

Usage Guidelines:

Interfaces can be extended from classes and are ideal for defining properties.

Types can be merged and are more suitable for non-composite properties. For instance, types can be used effectively in cases like the following:

type Direction = 'up' | 'down' | 'left' | 'right';

For further insights on types, check out this helpful resource here, or explore discussions on TypeScript: Interfaces vs Types.

Answer №2

Absolutely, it's achievable.

Step 1: Begin by crafting your model using "Classes". While TypeScript offers interfaces for similar functionality, the Angular team suggests utilizing a basic ES6 class with strongly typed instance variables. ES6 classes allow for additional functionality around your models and do not restrict you to TypeScript-specific features. Therefore, it is recommended to use classes when creating models.

export class DonutChartModel {

//Fields 
dimension: Number
innerRadius: Number
backgroundClass: Number
backgroundOpacity: Number
myPropertyToSet: String 

constructor (dimension: Number, innerRadius: Number){
   this.dimension = dimension
   this.innerRadius = innerRadius
}}

Step 2: Import the model into your component for increased reusability.

import { DonutChartModel } from '../../models/donut-chart-model;

Step 3: Set a value for one of the properties:

export class MenuSelectionPage {

  myDonuts: DonutChartModel[] = [];

  constructor(public navCtrl: NavController, public navParams: NavParams) {
    this.FillLocalData()
    this.myDonuts[this.myDonuts.length - 1].myPropertyToSet = "I am your father" 
  } 

  //Aux Methods
  FillLocalData() {
    let dimensions = [8.32, 5, 17];
    let defaultInnerRadius = 2;
    for (let i = 0; i < dimensions.length; i++) {
      let donut = new DonutChartModel (dimensions[i], defaultInnerRadius * i)
      this.myDonuts.push(donut)
    }
  }
}

Step 4 (Optional): Utilize it in HTML.

 ...
 <ion-list>
    <button ion-item *ngFor="let donut of myDonuts">
    {{donut.myPropertyToSet}}
     </button>
 </ion-list>
 ...

Note: This code has been successfully tested in Ionic 3

Answer №3

Setting default values for the fields will achieve the desired outcome.

class PieModel {
    slices: number = 0;
    radius: number = 0;
    fillClass: string = "";
    opacityLevel: number = 0;
}

Answer №4

If you are in search of the shorthand technique known as Parameter Properties, check out this useful resource:

export class DonutChartModel {
  constructor(
    dimension: number,
    innerRadius: number,
    backgroundClass: string,
    backgroundOpacity: number
  ) {}
}

Special thanks to Robert Komaromi and the author of this insightful article

Similar questions

If you have not found the answer to your question or you are interested in this topic, then look at other similar questions below or use the search

The type x cannot be assigned to the parameter '{ x: any; }'

Currently learning Angular and Typescript but encountering an error. It seems to be related to specifying the type, but I'm unsure of the exact issue. Still new at this, so any guidance is appreciated! src/app/shopping-list-new/shopping-edit/shopp ...

Working with TypeORM to establish two foreign keys pointing to a single primary key in a table

For my project, I am looking to establish bi-directional ManyToOne - OneToMany relationships with two foreign keys that reference the same primary key. Specifically, I have a 'match' table that includes two players from the 'player' tab ...

Step-by-step guide on deploying your Nestjs API on Google App Engine

Encountering a hurdle while trying to deploy my nestjs api on Google App Engine has left me puzzled. Despite initializing my google cloud project with the google sdk, an error thwarted my progress. To tackle this challenge, I made key adjustments in my cod ...

Angular checkboxes not updating with current values when submitted

I have defined a static array in TypeScript like this: permissions: any[] = [ { permission: "Read", enabled: true }, { permission: "Write", enabled: false }, { permission: "Delete", enabled: false }, { permission: "Edit", enabled: true } ...

Converting TypeScript to ES5 in Angular 2: A Comprehensive Guide

I am currently diving into Angular 2 and delving into Typescript to create simple applications within the Angular 2 framework. What I have discovered is that with Typescript, we can utilize classes, interfaces, modules, and more to enhance our application ...

What steps can I take to troubleshoot and fix the issue of a Duplicate identifier 'DateType' error during the React/Typescript building process

Utilizing the MUI library, I have also installed the @mui/x-date-pickers library. In order for my datepicker component to function properly, I need to install the @date-io/date-fns/ library as well. However, upon running yarn build, I encountered the fol ...

You won't find the property 'includes' on a type of 'string[]' even if you're using ES7 features

I encountered a similar issue on another page where it was suggested to modify the lib in tsconfig.josn. However, even after changing compile to es7, the same error kept appearing and the project couldn't be compiled or built. { "compileOnSave": ...

Create a mechanism in the API to ensure that only positive values greater than or equal to 0 are accepted

My goal is to process the API result and filter out any values less than 0. I've attempted to implement this feature, but so far without success: private handleChart(data: Object): void { const series = []; for (const [key, value] of Object.e ...

The generic parameter is extending a type but is being used in a contravariant position, causing TypeScript to struggle to unify it

When developing my functions, I aim to provide flexibility for consumers to use a wider type. However, I encounter issues when the type is used in a contravariant position and TypeScript raises complaints. Here is the simplified code snippet: function wra ...

Cannot upload the same file to both Spring and Angular twice

Having trouble uploading the same file twice. However, it works fine when uploading different files. Encountering an error under the Network tab in Chrome { timeStamp: ......, status: 417 error: 'Bad Request', message: 'Required reques ...

The requirement of the second parameter being optional or required will depend on the value of the first

Is there a way to make the second parameter of my function optional or required based on the value of the first parameter? Here's an example code snippet: enum Endpoint { USERS = '/users/:userId', ORDERS = '/orders' } typ ...

PhpStorm flawlessly detects ES7 type hinting errors

For my project, I have implemented TypeScript. While JavaScript's array includes() function has been valid since ECMA6, setting the lib parameter in tsconfig to "es6" results in a non-fatal error being thrown in the browser console when using the foll ...

Tips on utilising the datepicker solely with the calendar icon, avoiding the need for any input fields

I'm currently working on a Datatable filter and I would like to incorporate a calendar icon to facilitate date filtering by simply clicking on the Datatable Header. At this stage, I've managed to display a calendar Icon on my Datatable header, b ...

getting TypeScript configured with webpack

I am currently using Typescript to develop a back-end API utilizing graphql and express. To manage the project development and building process, I have implemented webpack. As part of my setup, I am employing raw-loader in order to load graphql schemas an ...

Explore the world of data manipulation in Angular by experimenting with different

Embarking on a fresh Angular 2 project centered around Photos and Users. The backend work is all done, with the API in place. I've already constructed those classes. Now, I find myself pondering... To manipulate these objects on the client end, wo ...

Issues with multiple validators in Angular 8 intricately intertwined

I'm facing an issue with a reactive form control that has multiple validators. Despite defining the validation methods, the form is not being validated as expected. Below is the code snippet illustrating my attempted solutions. Method 1: civilIdNumbe ...

Vue HeadlessUI Error: The function vue.defineComponent is not recognized

Trying to incorporate @headlessui/vue into my nuxt project has been a challenge. My attempt at using it looks like this: <template> <Menu> <MenuItems> <MenuItem>Item</MenuItem> </MenuItems> </Menu&g ...

Ways to display or conceal information depending on the dropdown choice

In my Angular project, I am dealing with a dropdown menu that is followed by some data displayed in a div element. component.html <select class="form-control" id="power" required> <option value="" disabled selected ...

Guide on incorporating typed components into module federation in React

I've been encountering an issue with setting the type of a custom component exposed through Webpack module federation. Though I have successfully exposed and used the component, Typescript is flagging an error regarding its type. The situation invol ...

What is the best way to specify a function parameter as the `QUnit` type using TypeScript in conjunction with QUnit?

In my project, which is partially written in TypeScript and licensed under MIT, I am utilizing QUnit. I have some TypeScript functions that require QUnit as a parameter, and I would like to define their types based on its interface from the typings. For e ...