CommandHandler not found exception with command payload

Question

I try to use a command DTO but his handler is not recognized. When I log the DTO, it is a simple object {...} without CreateUserCommand signature.

Here is my controller :

async index(@Body() createUserCommand: CreateUserCommand): Promise<User> {
    console.log(createUserCommand);
    return await this.commandBus.execute(createUserCommand);
  }

I get the following output :

 { 
    firstName: 'xxx',
    lastName: 'xxx',
    email: 'xxx@xxx.com',
    password: 'xxx'
}

When i try to use directly the command it is working :

const command = new CreateUserCommand();
command.firstName = 'xxx';
command.lastName = 'xxx';
command.email = 'xxx@xxx.com';
command.password = 'xxx';

return await this.commandBus.execute(createUserCommand);

The following output :

 CreateUserCommand { 
    firstName: 'xxx',
    lastName: 'xxx',
    email: 'xxx@xxx.com',
    password: 'xxx'
}

Is it possible to use a DTO as a command handler?

Answer 1

If you use @Body it will produce a plain javascript object but not an instance of your dto class. You can use class-transformer and its plainToClass(CreateUserCommand, createUserCommand) method to actually create an instance of your class.

If you are using the ValidationPipe it can automatically transform your plain object to a class if you pass the option transform: true:

@UsePipes(new ValidationPipe({ transform: true }))
async index(@Body() createUserCommand: CreateUserCommand): Promise<User> {
    console.log(createUserCommand);
    return await this.commandBus.execute(createUserCommand);
}