Spring-Web-Query: Simplify Filtering & Sorting in Spring Boot APIs

I understood how Spring injects dependencies… Now I explored how APIs actually work in Spring Boot What is a REST API? It allows applications to communicate using HTTP (GET, POST, PUT, DELETE) --- In Spring Boot, this is handled using @RestController It tells Spring: “This class will handle HTTP requests” --- Example flow: Client → sends request Controller → receives it Service → processes logic Response → sent back to client --- Key Annotations: • @RestController → marks class as API controller • @GetMapping → fetch data • @PostMapping → send data • @PutMapping → update data • @DeleteMapping → delete data --- In simple terms: @RestController = “Entry point of your backend” --- Learning step by step and building real backend skills Next: How Controller talks to Service layer internally #SpringBoot #Java #BackendDevelopment #RESTAPI #LearningInPublic

#Post6 In the previous posts, we built basic REST APIs step by step. But what happens when something goes wrong? 🤔 Example: User not found Invalid input Server error 👉 By default, Spring Boot returns a generic error response. But in real applications, we need proper and meaningful error handling. That’s where Exception Handling comes in 🔥 Instead of handling exceptions in every method, Spring provides a better approach using @ControllerAdvice 👉 It allows us to handle exceptions globally Example: @ControllerAdvice public class GlobalExceptionHandler { @ExceptionHandler(Exception.class) public String handleException(Exception ex) { return ex.getMessage(); } } 💡 Why use this? • Centralized error handling • Cleaner controller code • Better API response Key takeaway: Use global exception handling to manage errors in a clean and scalable way 🚀 In the next post, we will create custom exceptions for better control 🔥 #Java #SpringBoot #BackendDevelopment #RESTAPI #LearnInPublic

#Post2 In the previous post, we understood what a REST API is. Now the next question is 👇 How do we actually build REST APIs in Spring Boot? That’s where @RestController comes in 🔥 @RestController is a special annotation used to create REST APIs. It combines two things: • @Controller • @ResponseBody 👉 Meaning: Whatever method returns → it is written directly to the HTTP response body (usually JSON for objects) Example: @RestController public class UserController { @GetMapping("/user") public String getUser() { return "Hello User"; } } Output → "Hello User" (sent as response) 💡 Key difference: @Controller → used for returning views (JSP/HTML) @RestController → used for REST APIs (JSON response) Key takeaway: If you are building APIs in Spring Boot → @RestController is your starting point 🚀 In the next post, we will understand how request mapping works using @GetMapping and others 🔥 #Java #SpringBoot #BackendDevelopment #RESTAPI #LearnInPublic

Clean REST API in Spring Boot (Best Practice) 🚀 Here’s a simple structure you should follow 👇 📁 Controller - Handles HTTP requests 📁 Service - Business logic 📁 Repository - Database interaction Example 👇 @RestController @RequestMapping("/users") public class UserController { @Autowired private UserService userService; @GetMapping("/{id}") public User getUser(@PathVariable Long id) { return userService.getUserById(id); } } 💡 Why this matters: ✔ Clean code ✔ Easy testing ✔ Better scalability ⚠️ Avoid: Putting everything inside controller ❌ Structure matters more than code 🔥 Follow for more practical backend tips 🚀 #SpringBoot #Java #CleanArchitecture #Backend

@PathVariable vs @RequestParam – Passing URL Data While working on my Spring Boot projects, I explored how to pass data through URLs using @PathVariable and @RequestParam, and how both are used in different scenarios. 🔹 @PathVariable Used to get values directly from the URL path. It is mostly used when the value is required and represents a specific resource. Example: /users/101 → here 101 is taken as path variable 🔹 @RequestParam Used to get values from query parameters in the URL. It is commonly used for optional data like filters, search, or pagination. Example: /users?name=Rahul → here name is a request parameter Why use both? Using @PathVariable and @RequestParam properly makes APIs more clear and meaningful. @PathVariable → for identifying resources @RequestParam → for filtering or optional inputs In real projects, understanding this difference helps in designing clean and scalable REST APIs. #SpringBoot #Java #BackendDevelopment #RESTAPI #CodingJourney #LearningInPublic

🌟 Understanding Entity, Repository, and Service Layers in Spring Boot 📌 A well-structured Spring Boot application follows a layered architecture to ensure clean, maintainable, and scalable code. 👉 Entity Layer Represents the database structure. It defines how data is stored using annotations like @Entity and @Id. 👉 Repository Layer Handles database operations. Using Spring Data JPA, it provides built-in methods like save, find, and delete without writing SQL. 👉 Service Layer Contains the business logic of the application. It processes data, applies rules, and connects the controller with the repository. -->A well-structured application using these layers ensures clean code, scalability, and maintainability, which are essential for real-world backend development. #SpringBoot #Java #BackendDevelopment #SoftwareArchitecture #LearningInPublic

🧬 Spring Boot – Understanding API Responses Today I explored how Spring Boot sends data from backend to frontend. 🧠 Key Learnings: ✔️ Returning a Java object automatically converts it to JSON ✔️ Spring Boot uses Jackson internally for this conversion ✔️ "@ResponseBody" ensures data is sent directly as response 💡 Best Practice: 👉 Using "@RestController" simplifies everything (Combination of @Controller + @ResponseBody) ✔️ Explored different return types: • Object • List • String • ResponseEntity (for better control over status & response) 🔁 API Flow: Request → Controller → Service → Return Object → JSON Response → Client 💻DSA Practice: • Even/Odd check using modulus • Sum of first N numbers (optimized using formula) ✨ Understanding how backend responses work is key to building real-world REST APIs. #SpringBoot #Java #BackendDevelopment #RESTAPI #WebDevelopment #DSA #LearningInPublic #SoftwareEngineering

🚀 Exploring REST APIs with Spring Boot Today, I explored how REST APIs work along with the core Spring Boot annotations used to build them. I learned how client-server communication happens using HTTP methods like GET, POST, PUT, and DELETE, and how the server responds with structured data in JSON format. Along with that, I got hands-on understanding of important Spring Boot annotations: 🔹 @RestController → Handles REST requests and returns JSON responses 🔹 @RequestMapping → Maps HTTP requests to specific endpoints 🔹 @GetMapping, @PostMapping, @PutMapping, @DeleteMapping → Simplify API method handling 🔹 @PathVariable & @RequestParam → Used to pass data in APIs 🔹 @RequestBody → Used to receive data from the client 💡 Key Learning: I understood how these annotations reduce boilerplate code and make backend development more efficient and readable. Looking forward to building and implementing REST APIs in my upcoming projects using Spring Boot. #Java #SpringBoot #RESTAPI #BackendDevelopment #LearningJourney #SoftwareDevelopment

Everything failed… but the database still got updated 🙃. Recently, while working on a feature in Spring Boot project, I used @Transactional annotation assuming it would rollback the entire operation if something failed. But during testing, I noticed something strange, even after an exception, some data was still getting saved. That’s when I started digging deeper. I realized that @Transactional doesn’t always behave the way we expect: - It rolls back only for unchecked exceptions (RuntimeException) by default. - If the method call happens within the same class, it might not work due to proxy behavior. - Catching exceptions without rethrowing can prevent rollback. In my case, I was catching the exception and not rethrowing it. So Spring thought everything was fine and committed the transaction. Once I fixed that, the rollback worked as expected. Annotations make things easier… but understanding how they actually work makes you a better developer. #Java #SpringBoot #BackendDevelopment #Transactional #LearningInPublic #SoftwareEngineering #Database #SpringJPA #DataManagement

#Post3 In the previous post, we understood the role of @RestController in building APIs. Now the next step is 👇 How do we map HTTP requests to methods? That’s where mapping annotations come in 🔥 In Spring Boot, we use: • @GetMapping → for GET requests • @PostMapping → for POST requests • @PutMapping → for UPDATE • @DeleteMapping → for DELETE • @PatchMapping → for partial updates Example: @GetMapping("/users") → fetch all users @PostMapping("/users") → create a new user 💡 What about @RequestMapping? @RequestMapping is a generic annotation that can handle all HTTP methods. Example: @RequestMapping(value="/users", method=RequestMethod.GET) 👉 But in modern Spring Boot, we prefer specific annotations like @GetMapping for cleaner and readable code Key takeaway: Use specific mapping annotations for better clarity and maintainability 👍 In the next post, we will understand how @RequestBody works in handling request data 🔥 #Java #SpringBoot #BackendDevelopment #RESTAPI #LearnInPublic