The Router use the type `Params` for all of:
- position parameters,
- matrix parameters,
- query parameters.
`Params` is defined as follow `type Params = {[key: string]: any}`
Because parameters can either have single or multiple values, the type should
actually be `type Params = {[key: string]: string | string[]}`.
The client code often assumes that parameters have single values, as in the
following exemple:
```
class MyComponent {
sessionId: Observable<string>;
constructor(private route: ActivatedRoute) {}
ngOnInit() {
this.sessionId = this.route
.queryParams
.map(params => params['session_id'] || 'None');
}
}
```
The problem here is that `params['session_id']` could be `string` or `string[]`
but the error is not caught at build time because of the `any` type.
Fixing the type as describe above would break the build because `sessionId`
would becomes an `Observable<string | string[]>`.
However the client code knows if it expects a single or multiple values. By
using the new `ParamMap` interface the user code can decide when it needs a
single value (calling `ParamMap.get(): string`) or multiple values (calling
`ParamMap.getAll(): string[]`).
The above exemple should be rewritten as:
```
class MyComponent {
sessionId: Observable<string>;
constructor(private route: ActivatedRoute) {}
ngOnInit() {
this.sessionId = this.route
.queryParamMap
.map(paramMap => paramMap.get('session_id') || 'None');
}
}
```
Added APIs:
- `interface ParamMap`,
- `ActivatedRoute.paramMap: ParamMap`,
- `ActivatedRoute.queryParamMap: ParamMap`,
- `ActivatedRouteSnapshot.paramMap: ParamMap`,
- `ActivatedRouteSnapshot.queryParamMap: ParamMap`,
- `UrlSegment.parameterMap: ParamMap`
fixes#12869fixes#12889fixes#13885fixes#13870
Before this change there was a single injector tree.
Now we have 2 injector trees, one for the modules and one for the components.
This fixes lazy loading modules.
See the design docs for details:
https://docs.google.com/document/d/1OEUIwc-s69l1o97K0wBd_-Lth5BBxir1KuCRWklTlI4
BREAKING CHANGES
`ComponentFactory.create()` takes an extra optional `NgModuleRef` parameter.
No change should be required in user code as the correct module will be used
when none is provided
DEPRECATIONS
The following methods were used internally and are no more required:
- `RouterOutlet.locationFactoryResolver`
- `RouterOutlet.locationInjector`
BREAKING CHANGE:
Perviously, any provider that had an ngOnDestroy lifecycle hook would be created eagerly.
Now, only classes that are annotated with @Component, @Directive, @Pipe, @NgModule are eager. Providers only become eager if they are either directly or transitively injected into one of the above.
This also makes all `useValue` providers eager, which
should have no observable impact other than code size.
EXPECTED IMPACT:
Making providers eager was an incorrect behavior and never documented.
Also, providers that are used by a directive / pipe / ngModule stay eager.
So the impact should be rather small.
Fixes#14552
JB Nizet
Victor Berchet
Tobias Bosch
Jason Aden