aqary-assignment

Golang Demo

Note:

Install all the packages in the project and then run project by: go run main.go

This api is created in golang using gin framework, this api supports postgresql and used sqlc to generate code for the sql files provided. This project also uses the pgx/v5 as sql_package. six Endpoints will be exposed from this project.

This repo contains 3 different assignments

• Users Module
• Re-Arrange String Module
• Sql to Swap two consecutive students.

Users Module

A RESTful API using Golang with the Gin framework and PostgreSQL as the database and pgx as a database driver and sqlc for queries. The API should provide functionality to create a user, generate OTP for the user, and verify the OTP.

• POST /api/users >> Create Users
  • Accept JSON payload containing "name" & "phone_number"
  • Phone Number should be unique
  • Validation for phone number is important, it accepts phone number with (+).
  • Stores the user in the database.
• POST /api/users/generateotp >> Generates the OTP for user
  • Accepts JSON payload with phone_number.
  • If the phone_number does not exist, return a 404 error.
  • Generate a random 4-digit OTP and set its expiration time to 1 minute from the current time.
• POST /api/users/verifyotp >> Verify the OTP
  • Accepts JSON payload with phone_number and otp.
  • Check if the OTP is correct and not expired (compare with otp_expiration_time).
  • If the OTP is correct and not expired, return a success message.
  • If the OTP is incorrect, return an error message.
  • If the OTP is expired, return an error message indicating that the OTP has expired.

Re-Arrangement of String

Given a string s, rearrange the characters of s so that any two adjacent characters are not the same. Return any possible rearrangement of s or return "" if not possible.

Example: Input: s = "aab" Output: "aba"

Endpoint

POST "/api/rearrange-string" Body{"s": "aab"}

Swap Students Module

Solution to re-arrange the seat_id of every two consecutive students. If no of students is odd, the id of last student is not swapped.

GET "/api/swap-students"

Query

WITH RankedStudents AS (
    SELECT id, student,
           ROW_NUMBER() OVER (ORDER BY id) AS RowNum
    FROM Seat
),
SwappedStudents AS (
    SELECT id,
           CASE
               WHEN RowNum % 2 = 0 THEN (
                   SELECT id FROM RankedStudents
                   WHERE RowNum = s.RowNum - 1
               )
               ELSE (
                   SELECT id FROM RankedStudents
                   WHERE RowNum = s.RowNum + 1
               )
           END AS student
    FROM RankedStudents s
)
SELECT id, student
FROM SwappedStudents
ORDER BY id;