CODEWITHSUNDEEP
angularobjectundefined
raulnoob
raulnoob

Reputation: 119

Angular2 object cannot set property of undefined

So I have this little app in Angular2, and I'm trying to define an object. This is the main component.

export class ContactComponent  {
    person: {
    firstname: string;
    lastname: string;
}
constructor(private PeopleService: PeopleService){
}

ngOnInit(){

this.PeopleService.fetchData().subscribe(
    data=> {
        this.person.firstname=data.results[0].name.first;
        console.log(this.person.firstname);
    });
  }
}

Then in the console log I get:

Cannot set property 'firstname' of undefined

I can't figure it out. Thanks.

Upvotes: 10

Views: 17919

Answers (4)

Sandeep Shinde
Sandeep Shinde

Reputation: 31

  1. Firstly create an object in the component class. ex:

    employee=new Employee();

  2. Then refer to this employee object

Upvotes: 0

n00dl3
n00dl3

Reputation: 21564

You are just defining the type of person here (the colon stands for type annotations eg:propertyName:Type) :

person: {
    firstname: string;
    lastname: string;
}

What you have done here is telling the compiler that person is an object literal with 2 string properties firstname and lastname. It defines what can be store in that property, not what it contains.

You should assign a value first, otherwise, it will be undefined

interface Person {
    firstname ? : string; // the "?" makes the property optional, 
    lastname ? : string; //  so you can start with an empty object
}
export class ContactComponent {

    person: Person = {}; // initializing with an empty object

    constructor(private PeopleService: PeopleService) {}

    ngOnInit() {

        this.PeopleService.fetchData().subscribe(
            data => {
                this.person.firstname = data.results[0].name.first;
                console.log(this.person.firstname);
            });
    }
}

Upvotes: 15

Priyanka Arora
Priyanka Arora

Reputation: 457

First declare an object of person type on onInit().

person p=new person();

Upvotes: 0

Venkateswaran R
Venkateswaran R

Reputation: 478

Create a class and inherit in component. For Example see the below code

       export class Person{

            firstname: string;
            lastname: string;
        }
        export class ContactComponent  {
        person=Person[];
        constructor(private PeopleService: PeopleService){
        }

        ngOnInit(){

        this.PeopleService.fetchData().subscribe(
            data=> {
                this.person.firstname=data.results[0].name.first;
                console.log(this.person.firstname);
            });
          }
        }

Upvotes: 0

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