The Same API

Part of the TypeScript and NestJS section of Coddy's Node.js journey. Lesson 24 of 24.

Section 3's clients call /api/v1/tasks and use ?q=, ?sort= and ?limit=. These are the last pieces between your Nest API and that contract.

app.setGlobalPrefix('api/v1') in main.ts moves every route under the prefix, with no controller changed. The query options work like section 3's, with two differences: error codes are Nest's status names, like BAD_REQUEST, and a limit above 50 counts as 50 instead of getting 400.

const byPrice = [...products].sort((a, b) => a.price - b.price);

Sort a copy: sort reorders the array it is called on, and the service's array would stay reordered for every later request. Throw BadRequestException for a field you do not sort by; your filter gives it the error shape.

Challenge

Easy

The clients of your section 3 API call /api/v1/tasks, and they can search, sort and choose a page size. Give this Nest API the same paths and the same options.

In src/main.ts, inside bootstrap and before app.listen, set a global prefix of api/v1 with app.setGlobalPrefix. Every route moves under it: GET /tasks becomes GET /api/v1/tasks, and GET /stats becomes GET /api/v1/stats. No controller changes for this.
In src/tasks/tasks.controller.ts, findAll reads three more query options. Apply them after the done filter and before the page is cut, so that total and pages count only the tasks that match.
?q= searches titles. ?q=pizza keeps only the tasks whose title contains pizza, ignoring case, so Order PIZZA for the team matches.
?sort= orders the list. ?sort=title sorts by title, A to Z, and ?sort=createdAt sorts oldest first. A - in front reverses the order, so ?sort=-title is Z to A. Compare the values with localeCompare, as in section 3; createdAt is ISO text, which sorts in time order. Any other field, like ?sort=colour, gets 400: throw a BadRequestException, and your filter turns it into the error shape. Sort a copy of the list, never the service's own array, or every later request comes back sorted.
?limit= sets how many tasks fit on a page. Without ?limit, the page size stays PAGE_SIZE (2 here). A limit above 50 counts as 50: ?limit=500 returns 50 tasks per page, not an error. This differs from section 3.
page, total, pages and ?done= work as before, now with the new page size.

Try it: send GET /api/v1/tasks?sort=-title&limit=3. You get 200 and the tasks from Z to A, three to a page:

{
  "items": [
    { "id": 1, "title": "Write the README", "done": true, "createdAt": "2026-01-05T09:00:00.000Z" },
    { "id": 3, "title": "Plan the sprint", "done": false, "createdAt": "2026-01-07T08:15:00.000Z" },
    { "id": 2, "title": "Fix the login bug", "done": false, "createdAt": "2026-01-06T14:30:00.000Z" }
  ],
  "page": 1,
  "total": 3,
  "pages": 1
}

Send GET /api/v1/tasks?q=readme: only task 1, with "total": 1. Send GET /api/v1/tasks?sort=colour: 400 with { "error": { "code": "BAD_REQUEST", "message": "Cannot sort by colour" } }. Your message may be worded differently; the code is what counts. Send the old path, GET /tasks: 404 with { "error": { "code": "NOT_FOUND", "message": "Cannot GET /tasks" } }. POST and DELETE under /api/v1/tasks still need the header x-api-key: tasks-key-123.

Try it yourself

import { Body, Controller, Delete, Get, HttpCode, Inject, Param, ParseIntPipe, Post, Query, UseGuards } from '@nestjs/common';
import { ApiKeyGuard } from '../common/api-key.guard';
import { CreateTaskDto } from './dto/create-task.dto';
import { Task, TasksService } from './tasks.service';

@Controller('tasks')
export class TasksController {
    constructor(
        private readonly tasksService: TasksService,
        @Inject('PAGE_SIZE') private readonly pageSize: number,
    ) {}

    @Get()
    findAll(@Query('done') done?: string, @Query('page') page = '1') {
        const tasks = this.tasksService.findAll(done);
        const current = Number(page);
        const start = (current - 1) * this.pageSize;
        return {
            items: tasks.slice(start, start + this.pageSize),
            page: current,
            total: tasks.length,
            pages: Math.ceil(tasks.length / this.pageSize),
        };
    }

    @Get(':id')
    findOne(@Param('id', ParseIntPipe) id: number): Task {
        return this.tasksService.findOne(id);
    }

    @Post()
    @UseGuards(ApiKeyGuard)
    create(@Body() dto: CreateTaskDto): Task {
        return this.tasksService.create(dto);
    }

    @Delete(':id')
    @UseGuards(ApiKeyGuard)
    @HttpCode(204)
    remove(@Param('id', ParseIntPipe) id: number): void {
        this.tasksService.remove(id);
    }
}