Injector
Make sure to first read the introduction to dependency injection and the
@injectdocumentation.
All injection handler created by @injectable, @shared and @injectionHandler are registered in a global Injector instance exported as injector. The injector can also be used without decorators as this non-TypeScript example shows.
create(type, …parameters)
Where type can be any class and parameters (optional) are of the same type as the constructor parameters.
Creates an instance of the given type and fulfils all the constructor injections. The type itself does not have to be injectable. If it was the resolve method should be used instead. If parameters are given after the type they will be passed to the constructor, while all other constructor parameters will be injected (if decorated with @inject).
Example:
class Foo {
constructor(a: ClassA, @inject b: ClassB, @inject c: ClassC) {
//...
}
}
let foo = create(Foo, new ClassA());
The create method of the default global injector instance is also exported directly by 'tabris-decorators':
import {injector, create} from 'tabris-decorators';
console.log(injector.create === create);
resolve(type, injectionParameter?)
Where type can be any class and injectionParameter of any type.
Returns an instance for the given type, just like using the @inject decorator would do in a constructor. Especially useful in cases where the @inject decorator can not be used, e.g. outside of classes. Note that type has to be injectable, i.e. have a compatible injection handler registered. The second parameter may be omitted, or be used to pass a value to the injection handler. For further information see @injectable(config) and @injectionHandler(type).
The resolve method of the default global injector instance is also exported directly by 'tabris-decorators':
import {injector, resolve} from 'tabris-decorators';
console.log(injector.resolve === resolve);
addHandler({targetType, handler, priority?})
Where targetType is any class, handler is a Function returning a targetType instance and priority - if given - is a number.
Explicitly registers a new injection handler for targetType Same as using the injectionHandler decorator attached to the same Injector instance.
addHandler(targetType, handler)
Shorthand for addHandler({targetType, handler}).
register(targetType, value)
Makes the given value available for injection as the given target type. This differs from @shared in that it registers an existing instance, not a class that will be instantiated by the framework.
Same as calling addHandler(targetType, () => value).
The register method of the default global injector instance is also exported directly by 'tabris-decorators'.
Custom Injector instances
For unit tests or libraries it may be useful to create a separate Injector instance to keep the registered injection handlers separate.
To use the custom injector in other module, import the decorators/functions not from tabris-decorators but from a new module like this one:
import { Injector } from 'tabris-decorators';
export const injector = new Injector();
export const { inject, shared, injectable, injectionHandler, create, resolve} = injector;
export const JSX = injector.jsxProcessor;
Then import like this:
import { injector, inject, injectable, shared, injectionHandler, JSX } from './customInjector';
The JSX object must be imported whenever JSX expressions are used that should resolve injections with the given injector.
The Injector instance that was used to create a given object may be obtained by Injector.get(object). That is necessary if an object needs an injector instance (e.g. for calling injector.create()), but may be created by different injectors in different scenarios, for example in unit testing.
Example:
const newObject = Injector.get(this).create(InjectableType);
