Build and call a REST API

A REST-style API models resources with stable URLs, uses HTTP methods for intent, returns meaningful status codes, and keeps requests self-contained. Consistency is more valuable than chasing architectural purity.

At a glance

Question	Practical answer
When is it useful?	For /tasks, GET lists tasks, POST creates one, PATCH /tasks/42 changes selected fields, and DELETE /tasks/42 removes it when authorized.
What should you do?	Implement an in-memory task API with validation, then exercise its happy path and one invalid request using curl or an API client.
How do you know it worked?	Created resources return 201 and a stable identifier; invalid input returns 400 with a useful error; a missing resource returns 404.
Common failure	Avoid putting verbs into every URL or returning 200 for all outcomes; clients depend on predictable semantics.

flowchart LR
  A[Question] --> B[Build and call a REST API]
  B --> C[Small example]
  C --> D[Evidence]

The important idea is not to stop at a definition: connect the concept to a small example and observable evidence.

Worked example

For /tasks, GET lists tasks, POST creates one, PATCH /tasks/42 changes selected fields, and DELETE /tasks/42 removes it when authorized.

Before acting, write the success signal. Change one condition at a time, observe the result, and record assumptions. For Build and call a REST API, this separates what you know from what you are merely guessing.

Practice in 20–30 minutes

Goal: Implement an in-memory task API with validation, then exercise its happy path and one invalid request using curl or an API client.

1. Record the starting state and your prediction.
2. Implement the smallest version without adding unnecessary tools.
3. Change exactly one input or constraint and repeat.
4. Save a command, screenshot, output, or checklist as evidence.

Expected result: Created resources return 201 and a stable identifier; invalid input returns 400 with a useful error; a missing resource returns 404.

What can go wrong

Avoid putting verbs into every URL or returning 200 for all outcomes; clients depend on predictable semantics.

When the result differs from your prediction, do not change many things at once. Check inputs, versions, environment, permissions, and logs, then repeat from the smallest example.

Definition of done

• I can explain the concept in my own words.
• I completed the small example and kept evidence.
• I know one failure mode and how to check it.
• Someone else can repeat the work without guessing missing steps.

Go deeper

Use the linked resource or repository at the end of the page when you need a full implementation. Check current versions before applying commands to a real project.