Nest-kr/cqrs

This library is for CQRS

Installation

$ npm install --save @nest-kr/cqrs

How to use

Command

Import CqrsModule This module provides CommandBus and QueryBus

import {CqrsModule} from '@nest-kr/cqrs';

@Module({
    imports: [CqrsModule],
    controllers: [],
})
export class AppModule {}

Create Command

import { Command } from '@nest-kr/cqrs';

export class CreateUserCommand implements Command {
    ...
}

Create CommandResult (Optional)

import { CommandResult } from '@nest-kr/cqrs';

export class CreateUserResult implements CommandResult {
    ...
}

Create CommandHandler

@Injectable()
export class UserCommandService {
    ...

    @CommandHandler(CreateUserCommand)
    async create(command: CreateUserCommand): Promise<CreateUserResult> {
        
        return new CreateUserResult();
    }

Execute command

@Controller('users')
export class UserController {
    constructor(private readonly commandBus: CommandBus) {}

    @Post('/')
    async create() {
        const result: CreateUserResult = await this.commandBus.execute(new CreateUserCommand());
        return { message: 'user created', result };
    }
    ...
}

Query

Import CqrsModule This module provides CommandBus and QueryBus

import {CqrsModule} from '@nest-kr/cqrs';

@Module({
    imports: [CqrsModule],
    controllers: [],
})
export class AppModule {}

Create Query

import { Query } from '@nest-kr/cqrs';

export class GetUserQuery implements Query {
    ...
}

Create QueryResult

import { QueryResult } from '@nest-kr/cqrs';

export class GetUserQueryResult implements QueryResult {
    ...
}

Create QueryHandler

@Injectable()
export class UserQueryService {
    ...

    @QueryHandler(GetUserQuery)
    async create(query: GetUserQuery): Promise<GetUserQueryResult> {
        
        return new GetUserQueryResult();
    }

Execute query

@Controller('users')
export class UserController {
    constructor(private readonly queryBus: QueryBus) {}

    @Get('/:id')
    async get() {
        ...
        const result: GetUserQueryResult = await this.queryBus.execute(new GetUserQuery());
        return { message: 'get user', result };
    }
    ...
}