Handling path variables and query params together in Spring Boot - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output when accessing a Spring Boot endpoint with both path variable and query parameter?

Consider the following Spring Boot controller method:

@GetMapping("/users/{id}")
public String getUser(@PathVariable String id, @RequestParam(required = false) String filter) {
    return "User: " + id + ", Filter: " + (filter == null ? "none" : filter);
}

What will be the response body when a client sends a GET request to /users/42?filter=active?

Spring Boot

@GetMapping("/users/{id}")
public String getUser(@PathVariable String id, @RequestParam(required = false) String filter) {
    return "User: " + id + ", Filter: " + (filter == null ? "none" : filter);
}

A User: , Filter: active

B User: filter, Filter: active

C User: 42, Filter: active

D User: 42, Filter: none

💡 Hint

Remember that @PathVariable extracts the part of the URL path, and @RequestParam extracts query parameters.

The path variable 'id' captures '42' from the URL path, and the query parameter 'filter' captures 'active'. The method returns both values combined in the string.

📝 Syntax

intermediate

Which method signature correctly handles a path variable and an optional query parameter in Spring Boot?

You want to create a GET endpoint that accepts a path variable 'category' and an optional query parameter 'sort'. Which method signature is correct?

A public String listItems(@RequestParam(required = false) String category, @RequestParam String sort)

B public String listItems(@RequestParam String category, @PathVariable String sort)

C public String listItems(@PathVariable String category, @RequestParam String sort)

D public String listItems(@PathVariable String category, @RequestParam(required = false) String sort)

💡 Hint

Path variables come from the URL path, query parameters come after '?' and can be optional.

Option D correctly uses @PathVariable for 'category' and marks 'sort' as optional with @RequestParam(required = false). Option D requires 'sort' always, B swaps annotations incorrectly, and D uses @RequestParam for 'category' which should be a path variable.

🔧 Debug

advanced

Why does this Spring Boot method fail to bind the path variable correctly?

Given this controller method:

@GetMapping("/products/{id}")
public String getProduct(@RequestParam String id) {
    return "Product " + id;
}

What error or behavior will occur when accessing /products/10?

Spring Boot

@GetMapping("/products/{id}")
public String getProduct(@RequestParam String id) {
    return "Product " + id;
}

A HTTP 400 Bad Request error because 'id' query parameter is missing

B Returns 'Product 10' correctly

C HTTP 404 Not Found error because path variable is not matched

D Returns 'Product null' because id is null

💡 Hint

Check if the method parameter matches the URL path variable or query parameter.

The method expects 'id' as a query parameter (@RequestParam), but the URL provides it as a path variable. Since no query parameter 'id' is sent, Spring returns 400 Bad Request.

❓ state_output

advanced

What is the output of this Spring Boot controller method when called with /orders/5?status=shipped?

Analyze this method:

@GetMapping("/orders/{orderId}")
public String getOrder(@PathVariable int orderId, @RequestParam(defaultValue = "pending") String status) {
    return "Order " + orderId + " is " + status;
}

What will be the response body for the request /orders/5?status=shipped?

Spring Boot

@GetMapping("/orders/{orderId}")
public String getOrder(@PathVariable int orderId, @RequestParam(defaultValue = "pending") String status) {
    return "Order " + orderId + " is " + status;
}

A Order shipped is 5

B Order 5 is shipped

C Order 5 is pending

D Order null is shipped

💡 Hint

The query parameter 'status' overrides the default value.

The path variable 'orderId' is 5, and the query parameter 'status' is 'shipped', so the method returns 'Order 5 is shipped'.

🧠 Conceptual

expert

Which statement best describes handling path variables and query parameters together in Spring Boot?

Select the most accurate statement about using @PathVariable and @RequestParam together in a Spring Boot controller method.

A @PathVariable extracts values from the URL path, while @RequestParam extracts values from the query string; both can be used together in the same method.

B @RequestParam is used only for POST requests, and @PathVariable only for GET requests.

C You cannot use @PathVariable and @RequestParam in the same method because they conflict.

D @PathVariable extracts query parameters, and @RequestParam extracts path variables.

💡 Hint

Think about where each annotation gets its data from in the URL.

Option A correctly explains that @PathVariable gets data from the URL path segments, and @RequestParam gets data from the query string. They can be combined in one method.