Submodule 1 · Company Profile & REST APIs — Minimal Interactive (Styling Preserved)

Submodule 1 · Company Profile & REST APIs minimal

Goals: CRUD with Spring Boot + JPA, Many-to-Many, custom query. Most content is interactive ↓

Description: Experiment with a live mock REST API connected to an in-memory database. You can send POST, GET, PUT, and DELETE requests to create, read, update, and remove company records. The “Response” panel instantly displays the simulated JSON output just like a real server would return.
Learning Objective: Learn how RESTful endpoints behave in practice, how payloads and HTTP methods interact, and how client-server communication works without requiring a backend server setup.

Endpoint POST /api/companies GET /api/companies GET /api/companies/{id} PUT /api/companies/{id} DELETE /api/companies/{id}

Request Setup: Choose your endpoint and, if needed, specify the path parameter. This defines what operation the API will perform.

Path {id}

Body (JSON)

Request Body: Enter or modify the JSON payload that will be sent to the API for POST and PUT operations.

{ "name": "TechCorp", "industry": "Software", "location": "San Francisco", "size": 150, "skills": ["Java","Spring"], "roles": ["Backend","DevOps"] }

Response

Data Returned: The simulated server response showing either the object created, retrieved, or an error message.

Try a request!

Current Companies

Database Snapshot: View all company records currently stored in the in-memory dataset after your requests.

Description: Practice building repository query methods using Spring Data’s derived query syntax. Type a valid method declaration and check your syntax instantly. This helps reinforce how naming conventions automatically generate SQL under the hood.
Learning Objective: Strengthen your ability to construct expressive, readable data-access methods and understand how JPA abstracts database operations through convention over configuration.

One-liner: Derived query returning companies where size > minSize.

Code Input: Write a Spring Data JPA derived query that matches the described condition. Press “Check” to validate syntax.

Hint Section: Expand for guidance on correct naming conventions used by Spring Data repositories.

Hint

Use Spring Data naming: findBy<Field>GreaterThan(param).

Description: A short self-check that tests your understanding of Spring Boot annotations, ORM mapping, and asynchronous programming concepts. Each question reinforces key patterns from the lessons above.
Learning Objective: Verify your grasp of core Spring framework terminology, differentiate between controller and service layers, and recognize how async processing improves backend responsiveness.

Description: Use this form to simulate adding a new company record to your in-memory database. You can manually input details or click Cheat Fill to generate realistic sample data instantly. Once submitted, the record is appended to the dataset and displayed below in formatted JSON.
Learning Objective: Explore how frontend inputs become structured JSON requests, how POST payloads are formatted, and how backend APIs would process entity creation and persistence.

Form Inputs: Fill out the company details below or click “Cheat Fill” to auto-populate realistic sample data.

Name

IndustrySoftwareAIHealthcareFinance

Location

Size

Skills (comma)

Roles (comma)

Data Returned: Displays the exact JSON object that would be sent in a real POST request to the backend API.

Description: Reference key fragments from a simplified Spring Boot project, including repository definitions, controller endpoints, and configuration properties. Each snippet mirrors the functionality of your simulator for quick comparison.
Learning Objective: Understand how the controller delegates requests to the service layer, how JPA repositories simplify data queries, and how configuration files establish the link between application and database.

Repository

public interface CompanyRepository extends JpaRepository<Company, Long> {
  List<Company> findByIndustry(String industry);
  List<Company> findBySizeGreaterThan(Integer minSize);
  @Query("SELECT c FROM Company c JOIN c.skills s WHERE s.name = :skill")
  List<Company> findBySkillName(@Param("skill") String skill);
}

Controller

@RestController
@RequestMapping("/api/companies")
class CompanyController {
  @Autowired CompanyService svc;
  @PostMapping public ResponseEntity<Company> create(@RequestBody Company c){
    return new ResponseEntity<>(svc.createCompany(c), HttpStatus.CREATED);
  }
  @GetMapping("/{id}") public Company one(@PathVariable Long id){ return svc.getCompanyById(id); }
  @GetMapping public List<Company> all(){ return svc.getAllCompanies(); }
}

application.properties

spring.datasource.url=jdbc:sqlite:company_profiles.db
spring.datasource.driver-class-name=org.sqlite.JDBC
spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true

Entities/service omitted to keep it short—practice via Simulator & Builder.

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Styling background preserved; content trimmed; interactions unchanged.

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