I am calling router.navigate on same page with some query string parameters. In this case, ngOnInit() does not call. Is it by default or do I need to add anything else ?
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votes
12 Answers
157
votes
You can inject the ActivatedRoute and subscribe to params
constructor(route:ActivatedRoute) {
route.params.subscribe(val => {
// put the code from `ngOnInit` here
});
}
The router only destroys and recreates the component when it navigates to a different route. When only route params or query params are updated but the route is the same, the component won't be destroyed and recreated.
An alternative way to force the component to be recreated is to use a custom reuse strategy. See also Angular2 router 2.0.0 not reloading components when same url loaded with different parameters? (there doesn't seem to be much information available yet how to implement it)
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Here is a collection of the best ideas on this page with more information
Solution 1 - Use params subscription:
Tutorial: https://angular-2-training-book.rangle.io/routing/routeparams#reading-route-parameters
Docs: https://angular.io/api/router/ActivatedRoute#params
In each of your routing components that use param variables include the following:
import { Component, OnInit, OnDestroy } from '@angular/core';
import { ActivatedRoute } from '@angular/router';
import { Subscription } from 'rxjs';
// ...
@Component({
// ...
})
export class MyComponent implements OnInit, OnDestroy {
paramsSub: Subscription;
// ...
constructor(activeRoute: ActivatedRoute) {
}
public ngOnInit(): void {
// ...
this.paramsSub = this.activeRoute.params.subscribe(val => {
// Handle param values here
});
// ...
}
// ...
public ngOnDestroy(): void {
// Prevent memory leaks
this.paramsSub.unsubscribe();
}
}
Some common issues with this code is that subscriptions are asynchronous and can be trickier to deal with. Also you can't forget to unsubscribe on ngOnDestroy or else bad things can happen.
Good thing is that this is the most documented and common way to handle this problem. There's also a performance improvement doing it this way since you are reusing the template instead of destroying and recreating each time you visit a page.
Solution 2 - shouldReuseRoute / onSameUrlNavigation:
Docs: https://angular.io/api/router/ExtraOptions#onSameUrlNavigation
Docs: https://angular.io/api/router/RouteReuseStrategy#shouldReuseRoute
Docs: https://angular.io/api/router/ActivatedRouteSnapshot#params
Find where RouterModule.forRoot is located in your project (normally found in app-routing.module.ts or app.module.ts):
const routes: Routes = [
// ...
];
// ...
@NgModule({
imports: [RouterModule.forRoot(routes, {
onSameUrlNavigation: 'reload'
})],
exports: [RouterModule]
})
Then in AppComponent add the following:
import { Component, OnInit} from '@angular/core';
import { Router } from '@angular/router';
// ...
@Component({
// ...
})
export class AppComponent implements OnInit {
constructor(private router: Router) {
}
ngOnInit() {
// Allows for ngOnInit to be called on routing to the same routing Component since we will never reuse a route
this.router.routeReuseStrategy.shouldReuseRoute = function() {
return false;
};
// ...
}
// ...
}
Last, in your routing components you can now handle param variables like this:
import { Component, OnInit } from '@angular/core';
import { ActivatedRoute } from '@angular/router';
// ...
@Component({
// ...
})
export class MyComponent implements OnInit {
// ...
constructor(activeRoute: ActivatedRoute) {
}
public ngOnInit(): void {
// Handle params
const params = +this.activeRoute.snapshot.params;
// ...
}
// ...
}
Common issues with this solution is that it isn't common. Also you are changing the default behavior of the Angular framework, so you can run into issues people wouldn't normally run into.
Good thing is that all your code is synchronous and easier to understand.
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I've had the same issue, additionally I got the warning:
did you forget to call `ngZone.run()`
This site provided the best solution:
import { Router } from '@angular/router';
import { NgZone } from '@angular/core';
...
constructor(
private ngZone:NgZone,
private _router: Router
){ }
redirect(to) {
// call with ngZone, so that ngOnOnit of component is called
this.ngZone.run(()=>this._router.navigate([to]));
}
0
votes
This problem is likely coming from that fact that you are not terminating your subscriptions using ngOnDestroy. Here is how to get'ter done.
Bring in the following rxjs subscription import.
import { Subscription } from 'rxjs/Subscription';Add OnDestory to your Angular Core Import.
import { Component, OnDestroy, OnInit } from '@angular/core';Add OnDestory to your export class.
export class DisplayComponent implements OnInit, OnDestroy {Create a object property with a value of Subscription from rxjs under your export class for each subscription on the component.
myVariable: Subscription;Set the value of your subscription to MyVariable: Subscriptions.
this.myVariable = this.rmanagerService.getRPDoc(books[i].books.id).subscribe(value => {});Then right below ngOninit place the ngOnDestory() life cycle hook and put in your unsubscribe statement for your subscription. If you have multiple, add more
ngOnDestroy() { this.myVariable.unsubscribe(); }
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