Creating an interface and setting a default value

Question

Creating an interface and setting a default value

I am exploring the use of interfaces in my models and want to establish a default value for them.

export interface IPerson {
  id: string;
  name: string;
}

class Person implements IPerson {
   id = '';
   name = 'John';
}

export class Family {
 constructor(public address: string,
             public members: Person[] = [new Person()]) {
 }

My goal is to create a family where, if a person does not have a name defined, it defaults to John.

In some cases, a person gets created with a name set to null.

Any suggestions on how I can achieve this?

angular typescript interface

Answer 1

Answer №1

Typescript allows for the definition of value types, rather than the actual values themselves. You cannot define a value with an interface.

Instead, you can assign default values within a Person class:

class Person implements IPerson {
   constructor(private id='', private name= 'Jane') {
   }
}

Therefore, whenever the constructor is called with new Person(), it will instantiate an object with the preset values.

Answer 2

Typescript allows for the definition of value types, rather than the actual values themselves. You cannot define a value with an interface.

Instead, you can assign default values within a Person class:

class Person implements IPerson {
   constructor(private id='', private name= 'Jane') {
   }
}

Therefore, whenever the constructor is called with new Person(), it will instantiate an object with the preset values.

Answer 3

Answer №2

Type Script adheres to the principles of OOPS. Therefore, anything achievable with an OOPS based language can also be accomplished with Type Script. In terms of inheritance and initializing variables, your implementation seems sound and should function as intended.

To view a demonstration, visit - https://stackblitz.com/edit/angular-dbb7ij

Important Your class Family contains 2 parameters. The first is address which is a mandatory field since no default value was provided. The second parameter is an array of Users and it is considered optional due to the default value being an Array containing one entry of a new User.

Answer 4

Type Script adheres to the principles of OOPS. Therefore, anything achievable with an OOPS based language can also be accomplished with Type Script. In terms of inheritance and initializing variables, your implementation seems sound and should function as intended.

To view a demonstration, visit - https://stackblitz.com/edit/angular-dbb7ij

Important Your class Family contains 2 parameters. The first is address which is a mandatory field since no default value was provided. The second parameter is an array of Users and it is considered optional due to the default value being an Array containing one entry of a new User.

Answer 5

Answer №3

While I don't have much experience with TypeScript AngularJS syntax, it seems like you should consider creating an array of the Person class instead of using the IPerson interface. Your code might look something like this:

export class Home {
 constructor(public location: string,
         public residents: Person[] = [new Person()]) {
}

Answer 6

While I don't have much experience with TypeScript AngularJS syntax, it seems like you should consider creating an array of the Person class instead of using the IPerson interface. Your code might look something like this:

export class Home {
 constructor(public location: string,
         public residents: Person[] = [new Person()]) {
}

Answer 7

Answer №4

In the case where a class has the same name, there is no need to implement an interface.

    export interface PersonDetails {
      id?: string;
      name?: string;
    }

    export class Person {
      constructor(details?: PersonDetails) {
        return {
          id: details ? details.id : '',
          name: details ? details.name : 'John',
        }
      }
    }

    const individual = new Person(); // id = '', name = 'John'
    const individual2 = new Person({name: 'Morpheus'}); // id = '', name = 'Morpheus'

Answer 8

In the case where a class has the same name, there is no need to implement an interface.

    export interface PersonDetails {
      id?: string;
      name?: string;
    }

    export class Person {
      constructor(details?: PersonDetails) {
        return {
          id: details ? details.id : '',
          name: details ? details.name : 'John',
        }
      }
    }

    const individual = new Person(); // id = '', name = 'John'
    const individual2 = new Person({name: 'Morpheus'}); // id = '', name = 'Morpheus'

Creating an interface and setting a default value

Answer №1

Answer №2

Answer №3

Answer №4

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