Logo Questions Linux Laravel Mysql Ubuntu Git Menu
 

How can I define an array of objects?

Tags:

typescript

People also ask

What is array of objects with example?

Each variable or object in an array is called an element. Unlike stricter languages, such as Java, you can store a mixture of data types in a single array. For example, you could have array with the following four elements: an integer, a window object, a string and a button object.

How do you initialize an array of objects?

One way to initialize the array of objects is by using the constructors. When you create actual objects, you can assign initial values to each of the objects by passing values to the constructor. You can also have a separate member method in a class that will assign data to the objects.

Can we create array of objects in Java?

We know that an array is a collection of the same data type that dynamically creates objects and can have elements of primitive types. Java allows us to store objects in an array. In Java, the class is also a user-defined data type. An array that conations class type elements are known as an array of objects.

How do you declare an array of objects in C#?

You declare an array by specifying the type of its elements. If you want the array to store elements of any type, you can specify object as its type. In the unified type system of C#, all types, predefined and user-defined, reference types and value types, inherit directly or indirectly from Object.


You are better off using a native array instead of an object literal with number-like properties, so that numbering (as well as numerous other array functions) are taken care of off-the-shelf.

What you are looking for here is an inline interface definition for your array that defines every element in that array, whether initially present or introduced later:

let userTestStatus: { id: number, name: string }[] = [
    { "id": 0, "name": "Available" },
    { "id": 1, "name": "Ready" },
    { "id": 2, "name": "Started" }
];

userTestStatus[34978].nammme; // Error: Property 'nammme' does not exist on type [...]

If you are initializing your array with values right away, the explicit type definition is not a necessity; TypeScript can automatically infer most element types from the initial assignment:

let userTestStatus = [
    { "id": 0, "name": "Available" },
    ...
];

userTestStatus[34978].nammme; // Error: Property 'nammme' does not exist on type [...]

What you have above is an object, not an array.

To make an array use [ & ] to surround your objects.

userTestStatus = [
  { "id": 0, "name": "Available" },
  { "id": 1, "name": "Ready" },
  { "id": 2, "name": "Started" }
];

Aside from that TypeScript is a superset of JavaScript so whatever is valid JavaScript will be valid TypeScript so no other changes are needed.

Feedback clarification from OP... in need of a definition for the model posted

You can use the types defined here to represent your object model:

type MyType = {
    id: number;
    name: string;
}

type MyGroupType = {
    [key:string]: MyType;
}

var obj: MyGroupType = {
    "0": { "id": 0, "name": "Available" },
    "1": { "id": 1, "name": "Ready" },
    "2": { "id": 2, "name": "Started" }
};
// or if you make it an array
var arr: MyType[] = [
    { "id": 0, "name": "Available" },
    { "id": 1, "name": "Ready" },
    { "id": 2, "name": "Started" }
];

Some tslint rules are disabling use of [], example message: Array type using 'T[]' is forbidden for non-simple types. Use 'Array<T>' instead.

Then you would write it like:

var userTestStatus: Array<{ id: number, name: string }> = Array(
    { "id": 0, "name": "Available" },
    { "id": 1, "name": "Ready" },
    { "id": 2, "name": "Started" }
);

Array<T>

person: Array<{
  name: string;
  age: number;
}>