Angular - Why does invoking service call inside a component constructor sometimes render the UI twice?
This applies specifically to REST calls or Observer emit. I'm aware that I can and should make those calls after the component is initialised (ngOnInit) and when I do so, the issue is resolved. But I wonder why this behaviour occurs?
construct(private rest: RESTService) {
console.log('Component');
this.rest.findSomething().then(console.log);
}
In the logs, it appears that the component is initialised twice and hence the duplicate UI and zone.js makes two separate calls to the backend resulting in the data being repeatedly fetched. If I remove the rest call from there, the behaviour is normal.
angular
asked Nov 24 '18 at 1:35
Sorakthun LySorakthun Ly
130110
add a comment |
This applies specifically to REST calls or Observer emit. I'm aware that I can and should make those calls after the component is initialised (ngOnInit) and when I do so, the issue is resolved. But I wonder why this behaviour occurs?
construct(private rest: RESTService) {
console.log('Component');
this.rest.findSomething().then(console.log);
}
In the logs, it appears that the component is initialised twice and hence the duplicate UI and zone.js makes two separate calls to the backend resulting in the data being repeatedly fetched. If I remove the rest call from there, the behaviour is normal.
angular
asked Nov 24 '18 at 1:35
Sorakthun LySorakthun Ly
130110
Accusing to best practices constructors should be only used for injecting objects. Use onInit to call your services.
– Abdullah Khan
Nov 24 '18 at 1:39
add a comment |
This applies specifically to REST calls or Observer emit. I'm aware that I can and should make those calls after the component is initialised (ngOnInit) and when I do so, the issue is resolved. But I wonder why this behaviour occurs?
construct(private rest: RESTService) {
console.log('Component');
this.rest.findSomething().then(console.log);
}
In the logs, it appears that the component is initialised twice and hence the duplicate UI and zone.js makes two separate calls to the backend resulting in the data being repeatedly fetched. If I remove the rest call from there, the behaviour is normal.
angular
asked Nov 24 '18 at 1:35
Sorakthun LySorakthun Ly
130110
This applies specifically to REST calls or Observer emit. I'm aware that I can and should make those calls after the component is initialised (ngOnInit) and when I do so, the issue is resolved. But I wonder why this behaviour occurs?
construct(private rest: RESTService) {
console.log('Component');
this.rest.findSomething().then(console.log);
}
In the logs, it appears that the component is initialised twice and hence the duplicate UI and zone.js makes two separate calls to the backend resulting in the data being repeatedly fetched. If I remove the rest call from there, the behaviour is normal.
angular
angular
asked Nov 24 '18 at 1:35
Sorakthun LySorakthun Ly
130110
asked Nov 24 '18 at 1:35
Sorakthun LySorakthun Ly
130110
asked Nov 24 '18 at 1:35
Sorakthun LySorakthun Ly
130110
asked Nov 24 '18 at 1:35
Sorakthun LySorakthun Ly
130110
asked Nov 24 '18 at 1:35
Sorakthun LySorakthun Ly
130110
130110
Accusing to best practices constructors should be only used for injecting objects. Use onInit to call your services.
– Abdullah Khan
Nov 24 '18 at 1:39
add a comment |
Accusing to best practices constructors should be only used for injecting objects. Use onInit to call your services.
– Abdullah Khan
Nov 24 '18 at 1:39
Accusing to best practices constructors should be only used for injecting objects. Use onInit to call your services.
– Abdullah Khan
Nov 24 '18 at 1:39
Accusing to best practices constructors should be only used for injecting objects. Use onInit to call your services.
– Abdullah Khan
Nov 24 '18 at 1:39
add a comment |
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Accusing to best practices constructors should be only used for injecting objects. Use onInit to call your services.
– Abdullah Khan
Nov 24 '18 at 1:39