User Search API with Spring Boot and JPA Specifications

This project demonstrates a REST API for searching Users based on multiple criteria using Spring Boot, JPA, and JPA Specifications. It allows filtering users by firstName, lastName, and age parameters, with flexible criteria using dynamic specifications.

Features

• REST API for retrieving users based on dynamic search criteria
• Spring Data JPA Specifications for building flexible and maintainable queries
• Pattern Matching on firstName and lastName
• Age Filtering that allows searching for users above a specified age
• Clean and modular design with controllers, services, and repository layers separated for maintainability

Project Structure

• ProductController: Exposes the /users API endpoint for searching users.
• UserService: Contains business logic for user search.
• UserRepository: Extends JpaSpecificationExecutor to support specification-based queries.
• UserSpecification: Provides reusable JPA Specifications for various filter criteria (like firstName, lastName, and age).

API Endpoints

Search Users

Endpoint: GET /users

Query Parameters

• firstName (optional): Filter users by their first name (case-insensitive, partial match)
• lastName (optional): Filter users by their last name (case-insensitive, partial match)
• age (optional): Filter users older than a specified age

Sample Request

GET /users?firstName=John&lastName=Doe&age=25

Sample Response

[
  {
    "id": 1,
    "firstName": "John",
    "lastName": "Doe",
    "email": "john.doe@example.com",
    "age": 30
  },
  {
    "id": 2,
    "firstName": "Jane",
    "lastName": "Doe",
    "email": "jane.doe@example.com",
    "age": 28
  }
]

Implementation Details

Specification-based Filtering

The application uses JPA Specifications to dynamically build queries based on input parameters. Each filter criterion is represented as a specification:

• First Name Filter: Matches records where firstName contains the specified value (case-insensitive).
• Last Name Filter: Matches records where lastName contains the specified value (case-insensitive).
• Age Filter: Matches records where age is greater than the specified value.

Dependencies

• Spring Boot
• Spring Data JPA
• Postgres SQL