How to get the length of JSON array? - json

Question

I have a json url with a response of the following kind
[
{
"gender": "Female",
"age": 7,
"class": 2,
"subject": [
"",
"",
""
]
},
{
"gender": "Female",
"age": 8,
"class": 3,
"subject": [
"ab",
"cd",
"ef"
]
},
...
]
I want to find the length of this array
so in the angular app I am using
export class CustomComponent implements OnInit {
length: number;
constructor() {
this.length = Object.keys('www.url...').length;
console.log(length);
}
in .html I have
<p>{{ length }}</p>
I am getting 61 whereas the actual length is 44, but the console on the other hand is showing 0.
Where am I going wrong?
Any kind of help would be greatly appreciated. Thanks.

Answer 1

Easiest method.
import { Http } from '#angular/http';
export class CustomComponent implements OnInit {
length: number;
constructor(private http: Http){
this.http.request('www.url...',{method:'GET'}).map(response => response.json()).subscribe(result=>{
this.length=result.length;
});
}
}

Answer 2

Issue here is you are trying to execute Object.keys on url and not on
data , your url will be considered as string.
Solution is to use HttpClient :
// First get data from external url and then perform all operation
this.http.get('www.url...').subscribe(data => {
this.length = data.length;
console.log(length);
});