An orders REST API with Spring Boot and PostgreSQL

#Brief

The Olist dataset contains about 100,000 real orders from a Brazilian marketplace between 2016 and 2018, with customers, items, payments and reviews in separate CSV files. Build the API a front end or a partner would use to read and create orders.

#What to build

1. Design tables for orders, order items, customers and payments. Write them as migrations and load the CSVs.

2. GET /orders?status=&customerId=&page=&size= with pagination and a stable sort. GET /orders/{id} with items and payments.

3. POST /orders with validation (known customer, at least one item, positive prices) returning 201 and a Location header.

4. Consistent error responses (a JSON body with a code and field errors) through a controller advice.

5. Tests at two levels: service logic with plain JUnit, endpoints with MockMvc or an integration test against PostgreSQL (for example with Testcontainers).

#Deliverables

• Repository with the Spring Boot project, db/migration/, a loader, tests, openapi.yaml and README.md

#How it is graded

Reviewers start the service from your README, call every endpoint with valid and invalid input, and read your tests. They check that list endpoints stay fast with indexes on the columns you filter by.

#Stretch

Add ETag headers on GET /orders/{id} so clients can make conditional requests, with a test.