feat(router): Allow Route.redirectTo to be a function which returns a…

[atscott]

… string or UrlTree

This commit updates the logic around Route.redirectTo to enable using a function to create the redirect. This function can return a string, ands acts the same as previous string redirects, or a UrlTree, which will act as an absolute redirect.

To be useful, the redirect function needs access to the params and data. Today, developers can access these in their redirect strings, for example {path: ':id', redirectTo: '/user/:id'}. Unfortunately, developers only have access to params and data on the current route today in the redirect strings. The params and data in the RedirectFn give developers access to anything from the matched parent routes as well. This is done as the same way as param and data aggregation later on (

angular/packages/router/src/router_state.ts

Lines 236 to 278 in 897f014

	export function getInherited(
	route: ActivatedRouteSnapshot, parent: ActivatedRouteSnapshot|null,
	paramsInheritanceStrategy: ParamsInheritanceStrategy = 'emptyOnly'): Inherited {
	let inherited: Inherited;
	const {routeConfig} = route;
	if (parent !== null &&
	(paramsInheritanceStrategy === 'always' ||
	// inherit parent data if route is empty path
	routeConfig?.path === '' ||
	// inherit parent data if parent was componentless
	(!parent.component && !parent.routeConfig?.loadComponent))) {
	inherited = {
	params: {...parent.params, ...route.params},
	data: {...parent.data, ...route.data},
	resolve: {
	// Snapshots are created with data inherited from parent and guards (i.e. canActivate) can
	// change data because it's not frozen...
	// This first line could be deleted chose to break/disallow mutating the `data` object in
	// guards.
	// Note that data from parents still override this mutated data so anyone relying on this
	// might be surprised that it doesn't work if parent data is inherited but otherwise does.
	...route.data,
	// Ensure inherited resolved data overrides inherited static data
	...parent.data,
	// static data from the current route overrides any inherited data
	...routeConfig?.data,
	// resolved data from current route overrides everything
	...route._resolvedData,
	}
	};
	} else {
	inherited = {
	params: route.params,
	data: route.data,
	resolve: {...route.data, ...(route._resolvedData ?? {})}
	};
	}
	if (routeConfig && hasStaticTitle(routeConfig)) {
	inherited.resolve[RouteTitleKey] = routeConfig.title;
	}
	return inherited;
	}

). In order to accomplish this, we inherit params and data while matching, after the ActivatedRouteSnapshot is created for the matched route rather than waiting until the end.

The RedirectFunction does not return the full
ActivatedRouteSnapshot interface. Some things are not accurately known at the route matching phase. For example, resolvers are not run until later, so any resolved title would not be populated. The same goes for lazy loaded components. The is also true for all the snapshots up to the root, so properties that include parents (root, parent, pathFromRoot) are also excluded. And naturally, the full route matching hasn't yet happened so firstChild and children are not available either.

fixes #13373
resolves #28661 (though not for the redirect string - you would return a UrlTree from the function)

[atscott]

Updating target to major. This will likely need to be considered a breaking change. Expanding the type on the redirectTo results in build failures because places looking at the route config and expecting it to be a string will not work without a migration.

[jessicajaniuk]

reviewed-for: public-api

[atscott]

TESTED=https://fusion2.corp.google.com/presubmit/582101259/OCL:582101259:BASE:615787806:1710430124292:2547af3b;groups=PossiblyAlreadyFailing/targets (1 pre-existing failure)

[atscott]

This PR was merged into the repository by commit 2b80258.

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