In angular 2 how to preserve query params and add additional query params to route

For example I am on route /cars?type=coupe and I want to navigate to the same endpoint with additional query params (but keeping existing one). I am trying something like this

<a [routerLink]="['/cars']" [queryParams]="{model: 'renault'}" preserveQueryParams>Click</a>

The initial query params are preserved (type=cars) but added ones (model=renault) are ignored. Is this expected/correct behavior or is some kind of bug? Looks like preserveQueryParams has priority over queryParams? Is there any other smooth solution?

Answers:

Answer

In Angular 4+, preserveQueryParams have been deprecated in favor of queryParamsHandling. The options are either 'merge' or 'preserve'.

In-code example (used in NavigationExtras):

this.router.navigate(['somewhere'], { queryParamsHandling: "preserve" });

In-template example:

<a [routerLink]="['somewhere']" queryParamsHandling="merge">
Answer

It just works this way unfortunately:

const q = preserveQueryParams ? this.currentUrlTree.queryParams : queryParams;

You could try to add custom directive like this:

@Directive({selector: 'a[routerLink][merge]'})
export class RouterLinkDirective implements OnInit
{

    @Input()
    queryParams: {[k: string]: any};

    @Input()
    preserveQueryParams: boolean;


    constructor(private link:RouterLinkWithHref, private route: ActivatedRoute )
    {
    }

    public ngOnInit():void
    {
        this.link.queryParams = Object.assign(Object.assign({}, this.route.snapshot.queryParams), this.link.queryParams);
        console.debug(this.link.queryParams);
    }
}


<a [routerLink]="['/cars']" merge [queryParams]="{model: 'renault'}">Click</a>

Update: See DarkNeuron answer below.

Answer

There is an open issue and also already a pull request to make preserveQueryParams a router setting instead of a per navigation setting

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