Clean Architecture Scaffold

This CLI creates the structure of a NodeJs and TypeScript project based on clean architecture to build REST full APIs, it comes with the initial configuration of an Express application as a NodeJs framework and this is located in the application layer.

• Clean Architecture Scaffold
• Implementation of the plugin
• Tasks
  • Project Generation
  • Model Generation
  • Interface Generation
  • Interface Resource Generation
  • Service Generation
  • Service Resource Generation
  • Adapter ORM Generation
  • Singleton Instances
  • Adapter Simple Generation
  • Controller Generate
  • Decorators
  • Example of use case

Implementation of the plugin

We install the plugin globally in our computer, to be able to access the commands that generate the tasks. the tasks.

    npm i -g @tsclean/scaffold

Tasks

Project Generation

1. We generate the project structure with the command scaffold create:project, which receives one parameter --name.

   scaffold create:project --name=[project name]

   cd project name

Model Generation

1. The scaffold create:entity command will generate a model in the domain layer [models], this task has --name as parameter and this is required. The name must have a middle hyphen in case it is compound.

   Example: --name=user

   scaffold create:entity --name=user

Interface Generation

1. The scaffold create:interface command generates an interface, the location of the file is according to the component where it is required. where it is required. The name must have a hyphen in case it is a compound name.

   Example: --name=user, --name=user-detail, --name=post-comments-user.

   scaffold create:interface --name=user-detail --path=entities

   scaffold create:interface --name=user-detail --path=service

   scaffold create:interface --name=user-detail --path=infra

Interface Resource Generation

1. The command scaffold create:interface-resource generates an interface, this task has --name and --resource as parameters this is required. The name must be in lower case, as it is in the model.

   Note: It is recommended to create resource type interfaces when an entity is expected to be used in the contract implementation.

   Example: --name=user

   scaffold create:interface-resource --name=user --resource

Service Generation

1. The scaffold create:service command will generate the interface and the service that implements it in the domain layer [use-cases], this task has --name as parameter and this is required. The name must be hyphenated if it is a compound name.

   Example: --name=user, --name=user-detail, --name=post-comments-user.

   scaffold create:service --name=user

Service Resource Generation

1. The scaffold create:service-resource command will generate the interface and the service that implements it in the domain layer [use-cases], this task has --name as parameter and --resource this is required. The name must be in lower case, as it is in the model.

   Example: --name=user --resource

   scaffold create:service-resource --name=user --resource

Adapter ORM Generation

1. The scaffold create:adapter-orm command will generate an adapter in the infrastructure layer, this task has --name and --orm as parameters this is required. The name of the --manager parameter corresponds to the database manager. After the adapter is generated, the provider must be included in the app.ts file and then the name of the provider in the corresponding service must be passed through the constructor.

   Example: --name=user --orm=sequelize --manager=mysql

2. By convention the plugin handles names in singular, this helps to create additional code that benefits each component. In this case when you create the adapter with the name that matches the entity in the domain models folder, it does the automatic import in all the component of the adapter.

• command to generate a `mysql' adapter with sequelize orm.

   scaffold create:adapter-orm --name=user --orm=sequelize --manager=mysql

• command to generate a postgres adapter with sequelize orm

   scaffold create:adapter-orm --name=user --orm=sequelize --manager=pg

• command to generate the mongoose orm.

   scaffold create:adapter-orm --name=user --orm=mongo --manager=mongoose

Singleton Instances

In this version we add the management of the connections to the databases by means of the Singleton Pattern to create the instances, this was done in the index.ts file. These instances are added in the singletonInitializers array when the database connection adapter is created.

Example: When the adapter is created for postgres, the Singleton class is generated to make the connection to the database and the function is added to initialize it.

// src/application/config/pg-instance.ts
import { Sequelize } from 'sequelize-typescript'
import { Logger } from '@tsclean/core'
import { CONFIG_PG } from '@/application/config/environment'
import { UserModelPg } from '@/infrastructure/driven-adapters/adapters/orm/sequelize/models/user-pg'

/**
 * Class that generates a connection instance for Pg using the Singleton pattern
 */
export class PgConfiguration {
  /** Private logger instance for logging purposes */
  private logger: Logger

  /** Private static instance variable to implement the Singleton pattern */
  private static instance: PgConfiguration

  /** Sequelize instance for managing the PostgreSQL database connection */
  public sequelize: Sequelize

  /** Private constructor to ensure that only one instance is created */
  private constructor() {
    /** Initialize the logger with the class name */
    this.logger = new Logger(PgConfiguration.name)

    /** Create a new Sequelize instance with the provided configuration */
    this.sequelize = new Sequelize(
      CONFIG_PG.database,
      CONFIG_PG.user,
      CONFIG_PG.password,
      {
        host: CONFIG_PG.host,
        dialect: 'postgres',
        /** This array contains all the system models that are used for Pg. */
        models: [UserModelPg]
      }
    )
  }

  /** Method to get the instance of the class, following the Singleton pattern */
  public static getInstance(): PgConfiguration {
    if (!PgConfiguration.instance) {
      PgConfiguration.instance = new PgConfiguration()
    }
    return PgConfiguration.instance
  }

  /** Asynchronous method to manage the PostgreSQL database connection */
  public async managerConnectionPg(): Promise<void> {
    try {
      /** Attempt to authenticate the connection to the database */
      await this.sequelize.authenticate()
      /** Log a success message if the authentication is successful */
      this.logger.log(
        `Connection successfully to database of Pg: ${CONFIG_PG.database}`
      )
    } catch (error) {
      /** Log an error message if the authentication fails */
      this.logger.error('Failed to connect to Pg', error)
    }
  }
}

Note: Here you can declare all the Singleton instances that the application uses.

// src/application/singleton.ts
import { PgConfiguration } from '@/application/config/pg-instance'

/**
 * This array has all the singleton instances of the application
 */
export const singletonInitializers: Array<() => Promise<void>> = [
  async () => {
    const pgConfig = PgConfiguration.getInstance()
    await pgConfig.managerConnectionPg()
  }
]

Adapter Simple Generation

1. The scaffold create:adapter command will generate an adapter simple in the infrastructure layer, this task has --name as parameter and this is required.

   scaffold create:adapter --name=jwt

Controller Generation

1. The scaffold create:controller command will generate a controller in the infrastructure layer, this task has --name as parameter and this is required. The name must have a hyphen in case it is a compound name.

   Example: --name=user, --name=user-detail, --name=post-comments-user.

   scaffold create:controller --name=user-detail

Decorators

Decorators allow us to add annotations and metadata or change the behavior of classes, properties, methods, parameters and accessors.

@Services Decorator to inject the logic of this class as a service.

@Services
export class UserServiceImpl {}

@Adapter Decorator to keep the reference of an interface and to be able to apply the SOLID principle of Dependency Inversion.

// Constant to have the interface reference.
export const USER_REPOSITORY = 'USER_REPOSITORY'

export interface IUserRepository<T> {
  save: (data: T) => Promise<T>
}

@service
export class UserServiceImpl {
  constructor(
    @Adapter(USER_REPOSITORY)
    private readonly userRespository: IUserRepository
  ) {}
}

@Mapping Decorator that allows us to create the path of an end point.

@Mapping('api/v1/users')
export class UserController {}

Decorators HTTP

@Get() Decorator to solve a request for a specific resource.

@Post() Decorator used to send an entity to a specific resource.

@Put() Decorator that replaces the current representations of the target resource with the payload of the request.

@Delete() Decorator that deletes the specific resource.

@Params() Decorator to read the parameters specified in a method.

@Body() Decorator that passes the payload of a method in the request.

@Mapping('api/v1/users')
export class UserController {
  @Get()
  getAllUsers() {}

  @Get(':id')
  getByIdUser(@Params() id: string | number) {}

  @Post()
  saveUser(@Body() data: T) {}

  @Put(':id')
  updateByIdUser(@Params() id: string | number, @Body data: T) {}

  @Delete(':id')
  deleteByIdUser(@Params() id: string | number) {}
}

Example of use case

• Create a user in the store

1. Create the project.

scaffold create:project --name=store

2. Create entity user

scaffold create:entity --name=user

// src/domain/entities/user.ts
export type UserEntity = {
  id: string | number
  name: string
  email: string
}

export type AddUserParams = Omit<UserEntity, 'id'>

3. Create the contract to create the user.

scaffold create:interface --name=user --path=entities

// src/domain/entities/contracts/user-repository.ts
import { AddUserParams, UserModel } from '@/domain/entities/user'

export const USER_REPOSITORY = 'USER_REPOSITORY'

export interface IUserRepository {
  save: (data: AddUserParams) => Promise<UserModel>
}

4. Create services user

scaffold create:service --name=user

// src/domain/use-cases/user-service.ts
import { AddUserParams, UserEntity } from '@/domain/entities/user'

export const USER_SERVICE = 'USER_SERVICE'

export interface IUserService {
  save: (data: AddUserParams) => Promise<UserEntity>
}

// src/domain/use-cases/impl/user-service-impl.ts
import { Adapter, Service } from '@tsclean/core'
import { IUserService } from '@/domain/use-cases/user-service'
import { UserModel } from '@/domain/models/user'
import {
  IUserRepository,
  USER_REPOSITORY
} from '@/domain/models/contracts/user-repository'

@Service()
export class UserServiceImpl implements IUserService {
  constructor(
    // Decorator to keep the reference of the Interface, by means of the constant.
    @Adapter(USER_REPOSITORY)
    private readonly userRepository: IUserRepository
  ) {}

  /**
   * Method to send the data to the repository.
   * @param data {@code UserEntity}
   */
  async save(data: AddUserParams): Promise<UserEntity> {
    // Send the data to the repository.
    return this.userRepository.save({ ...data })
  }
}

5. Create mongoose adapter and additionally you must include the url of the connection in the .env file

scaffold create:adapter-orm --name=user --orm=mongo --manager=mongoose

// src/infrastructure/driven-adapters/adapters/orm/mongoose/models/user.ts
import { UserEntity } from '@/domain/entities/user'
import { model, Schema } from 'mongoose'

const schema = new Schema<UserEntity>(
  {
    id: {
      type: String
    },
    name: {
      type: String
    },
    email: {
      type: String
    }
  },
  { strict: false }
)

export const UserModelSchema = model<UserEntity>('users', schema)

// src/infrastructure/driven-adapters/adapters/orm/mongoose/user-mongoose-repository-adapter.ts
import { AddUserParams, UserEntity } from '@/domain/entities/user'
import { IUserRepository } from '@/domain/models/contracts/user-repository'
import { UserModelSchema as Schema } from '@/infrastructure/driven-adapters/adapters/orm/mongoose/models/user'

export class UserMongooseRepositoryAdapter implements IUserRepository {
  async save(data: AddUserParams): Promise<UserEntity> {
    return Schema.create(data)
  }
}

5.1 The scaffold automatically generates the connection instance

// src/application/config/mongoose-instance.ts
import { connect, set } from 'mongoose'
import { Logger } from '@tsclean/core'
import { MONGODB_URI } from '@/application/config/environment'

export class MongoConfiguration {
  private logger: Logger
  private static instance: MongoConfiguration

  private constructor() {
    this.logger = new Logger(MongoConfiguration.name)
  }

  public static getInstance(): MongoConfiguration {
    if (!this.instance) {
      this.instance = new MongoConfiguration()
    }
    return this.instance
  }

  public async managerConnectionMongo(): Promise<void> {
    set('strictQuery', true)

    try {
      await connect(MONGODB_URI)
      this.logger.log(
        `Connection successfully to database of Mongo: ${MONGODB_URI}`
      )
    } catch (error) {
      this.logger.error('Failed to connect to MongoDB', error)
    }
  }
}

5.2 The scaffold also includes the function in the array of singleton instances.

// src/application/singleton.ts
import { MongoConfiguration } from '@/application/config/mongoose-instance'

/** This array has all the singleton instances of the application */
export const singletonInitializers: Array<() => Promise<void>> = [
  async () => {
    const pgConfig = PgConfiguration.getInstance()
    await pgConfig.managerConnectionPg()
  }
]

5.3 These instances are called in the index.ts.

import 'module-alias/register'

import helmet from 'helmet'
import { StartProjectInit } from '@tsclean/core'

import { AppContainer } from '@/application/app'
import { PORT } from '@/application/config/environment'
import { singletonInitializers } from '@/application/singleton'

async function init(): Promise<void> {
  /** Iterate the singleton functions */
  for (const initFn of singletonInitializers) {
    await initFn()
  }

  const app = await StartProjectInit.create(AppContainer)
  app.use(helmet())
  await app.listen(PORT, () => console.log(`Running on port: ${PORT}`))
}

void init().catch()

6. Pass the key:value to do the dependency injections

// src/infrastructure/driven-adapters/providers/index.ts
import { USER_SERVICE } from '@/domain/use-cases/user-service'
import { USER_REPOSITORY } from '@/domain/models/contracts/user-repository'
import { UserServiceImpl } from '@/domain/use-cases/impl/user-service-impl'
import { UserMongooseRepositoryAdapter } from '@/infrastructure/driven-adapters/adapters/orm/mongoose/user-mongoose-repository-adapter'

export const adapters = [
  {
    // Constant referring to the interface
    provide: USER_REPOSITORY,
    // Class that implements the interface
    useClass: UserMongooseRepositoryAdapter
  }
]

export const services = [
  {
    // Constant referring to the interface
    provide: USER_SERVICE,
    // Class that implements the interface
    useClass: UserServiceImpl
  }
]

7. Create controller user

scaffold create:controller --name=user

// src/infrastructure/entry-points/api/user-controller.ts
import { Mapping, Post, Body } from '@tsclean/core'

import { AddUserParams, ModelUser } from '@/domain/models/user'
import { IUserService, USER_SERVICE } from '@/domain/use-cases/user-service'

@Mapping('api/v1/users')
export class UserController {
  constructor(
    // Decorator to keep the reference of the Interface, by means of the constant.
    @Adapter(USER_SERVICE)
    private readonly userService: IUserService
  ) {}

  @Post()
  async saveUserController(
    @Body() data: AddUserParams
  ): Promise<ModelUser | any> {
    // Send the data to the service through the interface.
    const user = await this.userService.save(data)

    return {
      message: 'User created successfully',
      user
    }
  }
}

8. Finally you can test this endpoint http://localhost:9000/api/v1/users, method POST in the rest client of your choice and send the corresponding data.