mapping.md

Response and request mapping

When receiving requests and sending responses, it is important to map the data from one format to another.

Guide

When receiving requests over HTTP REST, the requests are automatically mapped and validated when using a standard controller like so

import { Body, Controller, Get, Post, Query } from "@nestjs/common";
import { CommandBus, QueryBus } from "@nestjs/cqrs";
import { ApiTags } from "@nestjs/swagger";

import { CreateMonkeyCommand } from "../../application/contracts/commands/create-monkey.command";
import { MonkeyDetails } from "../../application/contracts/dtos/monkey.dto";
import { GetCurrentMonkeyQuery } from "../../application/contracts/queries/get-current-monkey.query";

@Controller("monkies")
@ApiTags("monkies")
export class MonkeyController {
  constructor(
    private commandBus: CommandBus,
    private queryBus: QueryBus,
  ) {}

  @Get()
  async getCurrentMonkey(
    @Query() query: GetCurrentMonkeyQuery,
  ): Promise<MonkeyDetails> {
    return await this.queryBus.execute(query);
  }

  @Post("/create")
  async createMonkey(@Body() command: CreateMonkeyCommand): Promise<null> {
    return await this.commandBus.execute(command);
  }
}

When constructing commands, queries or events in other occasions, this should be done using the mapAndValidate method like so

import { mapAndValidate } from "src/core/mapper";

import { CreateMonkeyCommand } from "../../application/contracts/commands/create-monkey.command";

async function doStuff(): Promise<void> {
  const myCommand = await mapAndValidate(CreateMonkeyCommand, {
    name: "my-name",
  });

  doStuffWithCommand(myCommand);
}

For constructing response models, the non-validating method map can be used instead.