This is an MCQ test-type project but in this, a user can share questions as a post, and his/her partners/friends can comment as an answer. Users can create groups and share their questions in those groups only. A user can give unlimited tests from an existing question bank. They can check their results to improve themselves.

Techs: SpringBoot,
Hibernate,
Spring Data JPA[ We can use Spring Data JPA to reduce the amount of boilerplate code required to implement the data access object (DAO) layer.
Spring Data JPA is not a JPA provider. It is a library/framework that adds an extra layer of abstraction on the top of our JPA provider (like Hibernate). It uses Hibernate as a default JPA provider. ],
Flyway, and PostgreSQL

Steps to run this project:
Step 1. create a database with a user using password
$ DROP DATABASE if exists learntogether;
$ CREATE DATABASE learntogether;
$ CREATE USER apu WITH ENCRYPTED PASSWORD 'tigerit';
$ GRANT ALL PRIVILEGES ON DATABASE learntogether to apu;
$ ALTER USER apu WITH SUPERUSER;

Or shortcut way to create a user
$ CREATE ROLE apu WITH LOGIN SUPERUSER PASSWORD 'tigerit';

Build project: $ mvn clean package Run: mvn spring-boot: run

To store all of the occupations into db from file through API call:
API: POST http://127.0.0.1:8080/service-api/api/profession/save-from-file
BODY: src\main\resources\profession_list.txt

Access and Refresh Token generation: for Admin user
URL: http://127.0.0.1:8080/service-api/oauth/token
Request Method: POST
Headers: Content-Type: application/x-www-form-urlencoded
Accept: application/json
Authorization: Basic {{$token}}
Here, $token: 'dGVzdC13ZWJhcHAtcnc6dGVzdC13ZWJhcHAtcnctMTIzNA=='
How to make token: Base64Encoded string of 'test-webapp-rw:test-webapp-rw-1234'
Body: grant_type: password
username: YOUR_USERNAME (here, admin@gmail.com)
password: YOUR_PASSWORD (1234) You will get the access and refresh token here

Now You can call the User related crud services:
HEADERS: Content-Type: application/json Authorization: Bearer {{access_token}}

GraphQL integration:

1. Add the dependency below:

com.graphql-java graphql-spring-boot-starter 3.6.0 com.graphql-java graphql-java-tools 3.2.0 2. create graphQL query 3. Create Datafetchers 4. Create GraphQLService 5. Create Resource/Controller for graphQL

Hazlecast Cache integration: \

1. Add the below depdendency to the pom.xml for the hazlecast secondary hibernate caching: \

com.hazelcast hazelcast-all 3.12.5

2. then add the configuration bean.
3. add the @EnableCaching to the main class
4. use the annotations: \
   while inserting or modification of data: @CachePut(value = "userCache", key = "#inputVariableName.id")
   while searching by id: @Cacheable(value = "userCache", key = "#id", unless = "#result==null")
   while deleting any data: @CacheEvict(value = "userCache", key = "#id")

Common Error:
Caused by: org.postgresql.util.PSQLException:
The authentication type 10 is not supported. Check that you have configured the pg_hba.conf file to include the client's IP address or subnet, and that it is using an authentication scheme supported by the driver.

Probable Solution:
Open postgresql.conf file location in windows: C:\Program Files\PostgreSQL\15\data

Update:
host all all 127.0.0.1/32 scram-sha-256
to
host all all 127.0.0.1/32 trust

Then restart the system