Factories

A Factory is responsible for the creation of other objects. Factories make it easy to create objects, often with the configurations we want. Often when creating objects, we do not need to set all the properties. We often leave properties with their default values. Factories provide a tool to streamline this process and create objects from different situations.

Defining a Factory

To define a factory, we can run the following command in our root directory.

domeniere create factory <module-name>/path/to/factory-name

This command will create a factory within the factories subdirectory of the module we specify.

Note: In order to create an factory, you need to have created a module that will contain the factory. See the Modules section for more details.

Below is an example of what a basic UserFactory would look like.

import { AbstractFactory } from '@domeniere/factory';
import { User } from './../../entities/entities.well';
import { UserRegistration } from './../../values/values.well';

export class UserFactory extends AbstractFactory {
    
    constructor() {
        super();
    }

    public createFromRegistration(registration: UserRegistration): User {
        // ...
        return user;
    }
}

We are really free to create as many factory functions as we need. In this example, we create a method to create a User entity from a UserRegistration object.

Registering Factories

Something important that we have to do in order to ensure our factories are available is to register them with our module. We register factories inside our module's createBindings() method.

To register our factory, we use the bindFactory() method.

this.bindFactory(UserFactory, (module) => {
    return new UserFactory();
});

The bindFactory() method takes two arguments. The first is the class name of the factory we want to bind. In this case, we are binding a UserFactory class. The second argument is a factory function that tells Domeniere how to instantiate our factory.

Once this is complete, we can now use our Factory in our application.

You can learn more about Module Bindings in the Modules section.