Inversify Generator

Inversify it's a great inversion of control container for TypeScript. But due to the nature of TypeScript and the inability to infer types at runtime Inversify and every other IoC for TypeScript relies on identifiers to assign an implementation to an abstraction.

This packages tries to make the process of assigning an identifier to an implementation a little less cumbersome by generating type identifiers and bindings for inversify automatically.

Install

yarn install inversify-generator

Usage

First you must configure the generator settings.

There are two ways, through command flags or through a inversify-generator.json config file.

Options

Option	Description	Default
tsconfig	Path to the tsconfig file	./tsconfig.json
output	Path to the output directory	./src/ioc
binding	Type of binding applied to the implementations in the generated file	default
watch	Watch files for binding and types generation	false

Type inversify-generator -h to see a list of available flags and how to use them.

inversify-generator.json config file example:

{
  "tsconfig": "./tsconfig.json",
  "output": "./src/ioc",
  "binding": "default"
}

Binding type

One of the configuration options it's binding. This configuration has two possibilities: default or dynamic.

The default will generate the bindings in a simple manner directly to the container as stated in inversify documentation:

Example of generated file with this binding:

import { Container } from "inversify";
import { TYPES } from "./types";
import { Ninja } from "./entities/ninja";
import { Katana } from "./entities/katana";
import { Shuriken } from "./entities/shuriken";

const myContainer = new Container();
myContainer.bind(TYPES.Warrior).to(Ninja);
myContainer.bind(TYPES.Weapon).to(Katana);
myContainer.bind(TYPES.ThrowableWeapon).to(Shuriken);

export { myContainer };

On the other hand the dynamic type will use a util exposed by this package that binds implementations with dynamic imports adding the possibility of creating providers (asynchronous factories).

If you are using inversify in a front end app, this method will probably make your main bundle smaller (as long as the sections that load the async factories are not executed) because it will only download the corresponding dependency chunks when needed.

This would be an example of the generated file by the dynamic binding type:

import { Container } from "inversify";
import { TYPES } from "./types";
import { bindDynamicModule } from "inversify-generator/utils";

const myContainer = new Container();
bindDynamicModule(TYPES.Warrior, () => import("./entities/ninja"), locator.bind);
bindDynamicModule(TYPES.Weapon, () => import("./entities/katana"), locator.bind);
bindDynamicModule(TYPES.ThrowableWeapon, () => import("./entities/shuriken"), locator.bind);

export { myContainer };

IMPORTANT Using dynamic binding has the current limitation that the function only binds the first exported module of the file. Meaning, if you have more than one class exported in the file and decorated with @injectable only the first one will be bound. So if you are using the dynamic type try having one class implementation per file.

Decorator util

This package also has a decorator util that will let you handle per dependency both scope, binding type and type identifier custom name.

By default, Inversify when binding a dependency it does it with the transient scope. With this util you will be able to configure the scope per dependency to be either transient or singleton.

Also, this decorator adds the ability to configure the binding type per dependency so that if you have one default binding configured (through flag or config file) you can select another one to a specific class.

Regarding the type identifier name, this util lets you change it from the one from default (that it's corresponding implementation, or it's class name if it does not implement anything).

import { generatorConf } from "inversify-generator/decorators";

@injectable()
@generatorConf({ scope: "singleton", biding: "default", typeName: "CoolRepo" })
export class FooRepository implements IFooRepository {
  @inject(TYPES.Service) private serviceProvider!: IocProvider<IService>;

  async baz(): Promise<Page<Post>> {
    const service = await this.serviceProvider();
    const baz = await service.get<Array<Record<string, unknown>>>("/baz");
    return baz.data;
  }
}

Roadmap

• Add typedoc
• Add request scope for configuration decorator.
• Add support for modules
• Add tests
• Add possibility to have several exported modules in a file to use with the dynamic binding method.