The rationale of this change is to improve the inter-operability with web
components that might make use of the `<template>` tag.
DEPRECATION
The template tags and template attribute are deprecated:
<template ngFor [ngFor]=items let-item><li>...</li></template>
<li template="ngFor: let item of items">...</li>
should be rewritten as:
<ng-template ngFor [ngFor]=items let-item><li>...</li></ng-template>
Note that they still be supported in 4.x with a deprecartion warning in
development mode.
MIGRATION
- `template` tags (or elements with a `template` attribute) should be rewritten
as a `ng-template` tag,
- `ng-content` selectors should be updated to referto a `ng-template` where they
use to refer to a template: `<ng-content selector="template[attr]">` should be
rewritten as `<ng-content selector="ng-template[attr]">`
- if you consume a component relying on your templates being actual `template`
elements (that is they include a `<ng-content selector="template[attr]">`). You
should still migrate to `ng-template` and make use of `ngProjectAs` to override
the way `ng-content` sees the template:
`<ng-template projectAs="template[attr]">`
- while `template` elements are deprecated in 4.x they continue to work.
Allow NgComponentOutlet to dynamically load a module, then load a component from
that module. Useful for lazy loading code, then add the lazy loaded code to the
page using NgComponentOutlet.
Closes#14043
- Introduce `InjectionToken<T>` which is a parameterized and type-safe
version of `OpaqueToken`.
DEPRECATION:
- `OpaqueToken` is now deprecated, use `InjectionToken<T>` instead.
- `Injector.get(token: any, notFoundValue?: any): any` is now deprecated
use the same method which is now overloaded as
`Injector.get<T>(token: Type<T>|InjectionToken<T>, notFoundValue?: T): T;`.
Migration
- Replace `OpaqueToken` with `InjectionToken<?>` and parameterize it.
- Migrate your code to only use `Type<?>` or `InjectionToken<?>` as
injection tokens. Using other tokens will not be supported in the
future.
BREAKING CHANGE:
- Because `injector.get()` is now parameterize it is possible that code
which used to work no longer type checks. Example would be if one
injects `Foo` but configures it as `{provide: Foo, useClass: MockFoo}`.
The injection instance will be that of `MockFoo` but the type will be
`Foo` instead of `any` as in the past. This means that it was possible
to call a method on `MockFoo` in the past which now will fail type
check. See this example:
```
class Foo {}
class MockFoo extends Foo {
setupMock();
}
var PROVIDERS = [
{provide: Foo, useClass: MockFoo}
];
...
function myTest(injector: Injector) {
var foo = injector.get(Foo);
// This line used to work since `foo` used to be `any` before this
// change, it will now be `Foo`, and `Foo` does not have `setUpMock()`.
// The fix is to downcast: `injector.get(Foo) as MockFoo`.
foo.setUpMock();
}
```
PR Close#13785
