Creating an array of objects in Angular 2

Question

Creating an array of objects in Angular 2

I'm facing an issue with the following expression:

public mySentences:Array<string> = [
    {id: 1, text: 'Sentence 1'},
    {id: 2, text: 'Sentence 2'},
    {id: 3, text: 'Sentence 3'},
    {id: 4, text: 'Sentenc4 '},
];

The problem lies in the fact that my array is not of type string, instead it contains a list of objects. How can I declare my array to hold a list of objects?

*without creating a new component and declaring a class for sentence which seems like a waste

arrays angular typescript

Answer 1

Answer №1

If you happen to be using TypeScript in your project.

For added safety, consider declaring your type as an array of objects that must adhere to a specific interface:

type CustomArrayType = Array<{id: number, text: string}>;

const customArr: CustomArrayType = [
    {id: 1, text: 'Statement 1'},
    {id: 2, text: 'Statement 2'},
    {id: 3, text: 'Statement 3'},
    {id: 4, text: 'Statement 4 '},
];

Alternatively, you can use a concise syntax without creating a separate type:

const customArr: Array<{id: number, text: string}> = [...];

Answer 2

If you happen to be using TypeScript in your project.

For added safety, consider declaring your type as an array of objects that must adhere to a specific interface:

type CustomArrayType = Array<{id: number, text: string}>;

const customArr: CustomArrayType = [
    {id: 1, text: 'Statement 1'},
    {id: 2, text: 'Statement 2'},
    {id: 3, text: 'Statement 3'},
    {id: 4, text: 'Statement 4 '},
];

Alternatively, you can use a concise syntax without creating a separate type:

const customArr: Array<{id: number, text: string}> = [...];

Answer 3

Answer №2

let sentenceList:Array<Object> = [
    {id: 1, text: 'Sentence 1'},
    {id: 2, text: 'Sentence 2'},
    {id: 3, text: 'Sentence 3'},
    {id: 4, text: 'Sentenc4 '},
];

Alternatively,

export interface SentenceType{
    id:number;
    text:string;
}

let sentenceList:SentenceType[] = [
    {id: 1, text: 'Sentence 1'},
    {id: 2, text: 'Sentence 2'},
    {id: 3, text: 'Sentence 3'},
    {id: 4, text: 'Sentenc4 '},
];

Answer 4

let sentenceList:Array<Object> = [
    {id: 1, text: 'Sentence 1'},
    {id: 2, text: 'Sentence 2'},
    {id: 3, text: 'Sentence 3'},
    {id: 4, text: 'Sentenc4 '},
];

Alternatively,

export interface SentenceType{
    id:number;
    text:string;
}

let sentenceList:SentenceType[] = [
    {id: 1, text: 'Sentence 1'},
    {id: 2, text: 'Sentence 2'},
    {id: 3, text: 'Sentence 3'},
    {id: 4, text: 'Sentenc4 '},
];

Answer 5

Answer №3

Here is an alternative method that can be particularly beneficial when storing data retrieved from an external API or database:

To begin, develop a class that defines your data model

export class Data{
    private id:number;
    private text: string;

    constructor(id,text) {
        this.id = id;
        this.text = text;
    }

Within your component class, create an empty array of type Data and populate this array each time you receive a response from the API or other data source being utilized

export class AppComponent {
    private search_key: string;
    private dataList: Data[] = [];

    getWikiData() {
       this.httpService.getDataFromAPI()
        .subscribe(data => {
          this.parseData(data);
        });
     }

    parseData(jsonData: string) {
    //assuming the data is received in JSON arrays
    for (let i = 0; i < jsonData[1].length; i++) {
         const data = new WikiData(jsonData[1][i], jsonData[2][i]);
         this.wikiData.push(data);
    }
  }
}

Answer 6

Here is an alternative method that can be particularly beneficial when storing data retrieved from an external API or database:

To begin, develop a class that defines your data model

export class Data{
    private id:number;
    private text: string;

    constructor(id,text) {
        this.id = id;
        this.text = text;
    }

Within your component class, create an empty array of type Data and populate this array each time you receive a response from the API or other data source being utilized

export class AppComponent {
    private search_key: string;
    private dataList: Data[] = [];

    getWikiData() {
       this.httpService.getDataFromAPI()
        .subscribe(data => {
          this.parseData(data);
        });
     }

    parseData(jsonData: string) {
    //assuming the data is received in JSON arrays
    for (let i = 0; i < jsonData[1].length; i++) {
         const data = new WikiData(jsonData[1][i], jsonData[2][i]);
         this.wikiData.push(data);
    }
  }
}

Answer 7

Answer №4

To begin, create a new Interface

If you are working with TypeScript & Angular CLI, you can generate an interface using the following command

ng g interface car

Next, define the data types for its properties

// car.interface.ts
export interface car {
  id: number;
  eco: boolean;
  wheels: number;
  name: string;
}

You can now import your interface into the desired class.

import {car} from "app/interfaces/car.interface";

Then, update the collection/array of car objects by adding items to the array.

this.car.push({
  id: 12345,
  eco: true,
  wheels: 4,
  name: 'Tesla Model S',
});

Further information on interfaces:

An interface is specific to TypeScript and not part of ECMAScript. It acts as a contract defining the function's expected arguments and their types. In addition to functions, interfaces can also be applied to Classes to establish custom types. Interfaces are abstract types that do not contain any code like classes. They solely outline the 'signature' or structure of an API. When transpiled, an interface doesn't produce any code; it's used by Typescript for type validation during development. -

Answer 8

To begin, create a new Interface

If you are working with TypeScript & Angular CLI, you can generate an interface using the following command

ng g interface car

Next, define the data types for its properties

// car.interface.ts
export interface car {
  id: number;
  eco: boolean;
  wheels: number;
  name: string;
}

You can now import your interface into the desired class.

import {car} from "app/interfaces/car.interface";

Then, update the collection/array of car objects by adding items to the array.

this.car.push({
  id: 12345,
  eco: true,
  wheels: 4,
  name: 'Tesla Model S',
});

Further information on interfaces:

An interface is specific to TypeScript and not part of ECMAScript. It acts as a contract defining the function's expected arguments and their types. In addition to functions, interfaces can also be applied to Classes to establish custom types. Interfaces are abstract types that do not contain any code like classes. They solely outline the 'signature' or structure of an API. When transpiled, an interface doesn't produce any code; it's used by Typescript for type validation during development. -

Answer 9

Answer №5

const myPhrases:Array<any> = [
    {id: 1, text: 'Phrase 1'},
    {id: 2, text: 'Phrase 2'},
    {id: 3, text: 'Phrase 3'},
    {id: 4, text: 'Phrase 4 '}
];

OR

const myPhrases:Array<object> = [
    {id: 1, text: 'Phrase 1'},
    {id: 2, text: 'Phrase 2'},
    {id: 3, text: 'Phrase 3'},
    {id: 4, text: 'Phrase 4 '}
];

Answer 10

const myPhrases:Array<any> = [
    {id: 1, text: 'Phrase 1'},
    {id: 2, text: 'Phrase 2'},
    {id: 3, text: 'Phrase 3'},
    {id: 4, text: 'Phrase 4 '}
];

OR

const myPhrases:Array<object> = [
    {id: 1, text: 'Phrase 1'},
    {id: 2, text: 'Phrase 2'},
    {id: 3, text: 'Phrase 3'},
    {id: 4, text: 'Phrase 4 '}
];

Answer 11

Answer №6

To declare an array with a specific datatype in TypeScript, use the following syntax:

array_name:datatype[]=[]; Example: users:string[]=[];

If you need to declare an array of objects:

Use this syntax for object type arrays:

object_name:objecttype[]=[{}]; Example: Users:user[]=[{}];

In cases where the array might be undefined during binding, be sure to initialize it in the OnInit() method.

Answer 12

To declare an array with a specific datatype in TypeScript, use the following syntax:

array_name:datatype[]=[]; Example: users:string[]=[];

If you need to declare an array of objects:

Use this syntax for object type arrays:

object_name:objecttype[]=[{}]; Example: Users:user[]=[{}];

In cases where the array might be undefined during binding, be sure to initialize it in the OnInit() method.

Answer 13

Answer №7

declare type NumberList = Array<{id: number, value: string}>;

const numberList: NumberList = [
    {id: 0, value: 'Zero'},
    {id: 1, value: 'One'},
    {id: 2, value: 'Two'},
    {id: 3, value: 'Three '},
    {id: 4, value: 'Four '},
    {id: 5, value: 'Five '},
];

Answer 14

declare type NumberList = Array<{id: number, value: string}>;

const numberList: NumberList = [
    {id: 0, value: 'Zero'},
    {id: 1, value: 'One'},
    {id: 2, value: 'Two'},
    {id: 3, value: 'Three '},
    {id: 4, value: 'Four '},
    {id: 5, value: 'Five '},
];

Creating an array of objects in Angular 2

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

Answer №7

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