Request mapping by method and path in Spring Boot - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to map a GET request to the path "/hello".

Spring Boot

@RestController
public class HelloController {
    @RequestMapping(value = "/hello", method = RequestMethod.[1])
    public String sayHello() {
        return "Hello!";
    }
}

Drag options to blanks, or click blank then click option'

AGET

BPOST

CPUT

DDELETE

Attempts:

3 left

💡 Hint

Common Mistakes

Using POST instead of GET for retrieving data.

Omitting the method attribute, which defaults to all methods.

The @RequestMapping annotation uses method = RequestMethod.GET to handle GET requests.

2fill in blank

medium

Complete the code to map a POST request to the path "/submit".

Spring Boot

@RestController
public class SubmitController {
    @RequestMapping(value = "/submit", method = RequestMethod.[1])
    public String submitData() {
        return "Submitted!";
    }
}

Drag options to blanks, or click blank then click option'

AGET

BPATCH

COPTIONS

DPOST

Attempts:

3 left

💡 Hint

Common Mistakes

Using GET instead of POST for data submission.

Confusing PATCH with POST.

The POST method is used to submit data to the server.

3fill in blank

hard

Fix the error in the code to correctly map a DELETE request to "/remove".

Spring Boot

@RestController
public class RemoveController {
    @RequestMapping(value = "/remove", method = RequestMethod.[1])
    public String removeItem() {
        return "Removed!";
    }
}

Drag options to blanks, or click blank then click option'

APUT

BDELETE

CGET

DPOST

Attempts:

3 left

💡 Hint

Common Mistakes

Using GET or POST instead of DELETE for removal.

Forgetting to specify the method attribute.

DELETE method is used to remove resources at the specified path.

4fill in blank

hard

Fill both blanks to map a PUT request to "/update" and specify the method correctly.

Spring Boot

@RestController
public class UpdateController {
    @RequestMapping(value = [1], method = RequestMethod.[2])
    public String updateItem() {
        return "Updated!";
    }
}

Drag options to blanks, or click blank then click option'

A"/update"

B"/edit"

CGET

DPUT

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong path string or missing quotes.

Using GET instead of PUT for updates.

The path should be "/update" and the method PUT for updating resources.

5fill in blank

hard

Fill all three blanks to map a PATCH request to "/modify", specify the method, and return a response.

Spring Boot

@RestController
public class ModifyController {
    @RequestMapping(value = [1], method = RequestMethod.[2])
    public String modifyItem() {
        return [3];
    }
}

Drag options to blanks, or click blank then click option'

A"/modify"

BPATCH

C"Modified!"

D"/change"

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong HTTP method for partial updates.

Forgetting quotes around strings.

The path is "/modify", the method is PATCH, and the return string is "Modified!".

Practice

1. What does the @RequestMapping annotation do in Spring Boot?

easy

A. It styles the HTML page returned by the controller.

B. It creates a new database connection automatically.

C. It links a URL path and HTTP method to a specific method in a controller.

D. It schedules background tasks to run periodically.

Solution

1. Step 1: Understand the purpose of @RequestMapping

   @RequestMapping is used to connect web requests to controller methods in Spring Boot.

2. Step 2: Identify what it links

   It links both the URL path and the HTTP method (GET, POST, etc.) to the method that should handle the request.

3. Final Answer:

   It links a URL path and HTTP method to a specific method in a controller. -> Option C

4. Quick Check:

   @RequestMapping links URL and method [OK]

Hint: Remember: @RequestMapping connects URL + HTTP method to code [OK]

Common Mistakes:

• Thinking @RequestMapping styles HTML output
• Confusing it with database or scheduling annotations
• Assuming it only maps URL without HTTP method

2. Which of the following is the correct way to map a GET request to path "/home" using @RequestMapping?

easy

A. @RequestMapping(route = "/home", method = GET)

B. @RequestMapping(path = "/home", method = RequestMethod.GET)

C. @RequestMapping(value = "/home", type = "GET")

D. @RequestMapping(method = "GET", url = "/home")

Solution

1. Step 1: Recall correct @RequestMapping syntax

   The correct syntax uses 'path' or 'value' for URL and 'method' with RequestMethod enum for HTTP method.

2. Step 2: Match options with syntax

   @RequestMapping(path = "/home", method = RequestMethod.GET) uses path and method=RequestMethod.GET correctly. Others use invalid attribute names or wrong types.

3. Final Answer:

   @RequestMapping(path = "/home", method = RequestMethod.GET) -> Option B

4. Quick Check:

   Correct syntax [OK]

Hint: Use 'path' and RequestMethod.GET for GET mapping [OK]

Common Mistakes:

• Using 'url' instead of 'path' or 'value'
• Passing HTTP method as string instead of RequestMethod enum
• Using wrong attribute names like 'route' or 'type'

3. Given this controller method:

@RequestMapping(path = "/test", method = RequestMethod.POST)
public String test() {
    return "Success";
}

What happens when a client sends a GET request to "/test"?

medium

A. The server crashes with an exception.

B. The method runs and returns "Success".

C. Spring returns a 404 Not Found error.

D. Spring returns a 405 Method Not Allowed error.

Solution

1. Step 1: Identify the mapped HTTP method

   The method is mapped only to POST requests at path "/test".

2. Step 2: Understand what happens on GET request

   A GET request to the same path is not handled, so Spring returns 405 Method Not Allowed.

3. Final Answer:

   Spring returns a 405 Method Not Allowed error. -> Option D

4. Quick Check:

   GET to POST-only path = 405 error [OK]

Hint: GET request to POST-only path causes 405 error [OK]

Common Mistakes:

• Assuming GET runs the POST method
• Thinking it returns 404 Not Found instead
• Believing server crashes on wrong method

4. What is wrong with this mapping?

@RequestMapping(path = "/data", method = "POST")
public String saveData() {
    return "Saved";
}

medium

A. The method attribute should use RequestMethod.POST, not a string.

B. The path attribute cannot be used with @RequestMapping.

C. The method must return void, not String.

D. The method name must be saveDataPost, not saveData.

Solution

1. Step 1: Check method attribute type

   The method attribute expects a RequestMethod enum value, not a string.

2. Step 2: Identify correct usage

   Using method = "POST" is invalid; it should be method = RequestMethod.POST.

3. Final Answer:

   The method attribute should use RequestMethod.POST, not a string. -> Option A

4. Quick Check:

   method attribute needs RequestMethod enum [OK]

Hint: Use RequestMethod.POST enum, not string "POST" [OK]

Common Mistakes:

• Passing HTTP method as string instead of enum
• Thinking path attribute is invalid
• Assuming return type or method name causes error

5. You want to create two methods in a controller: one handles GET requests at "/items" and another handles POST requests at the same path "/items". Which is the best way to do this?

hard

A. Use two methods with @RequestMapping(path = "/items", method = RequestMethod.GET) and @RequestMapping(path = "/items", method = RequestMethod.POST).

B. Use one method with @RequestMapping(path = "/items") and check HTTP method inside the method manually.

C. Use @RequestMapping(path = "/items") on both methods without specifying method attribute.

D. Use @RequestMapping(method = RequestMethod.GET) on one method and @RequestMapping(method = RequestMethod.POST) on the other without path.

Solution

1. Step 1: Understand how to map same path with different methods

   Spring allows multiple methods mapped to the same path but different HTTP methods using method attribute.

2. Step 2: Evaluate options

   Use two methods with @RequestMapping(path = "/items", method = RequestMethod.GET) and @RequestMapping(path = "/items", method = RequestMethod.POST). correctly uses two methods with same path but different HTTP methods. Use one method with @RequestMapping(path = "/items") and check HTTP method inside the method manually. is less clean and error-prone. Use @RequestMapping(path = "/items") on both methods without specifying method attribute. causes ambiguity. Use @RequestMapping(method = RequestMethod.GET) on one method and @RequestMapping(method = RequestMethod.POST) on the other without path. misses path, so won't map correctly.

3. Final Answer:

   Use two methods with @RequestMapping(path = "/items", method = RequestMethod.GET) and @RequestMapping(path = "/items", method = RequestMethod.POST). -> Option A

4. Quick Check:

   Separate methods with same path, different HTTP methods [OK]

Hint: Map same path with different methods by specifying method attribute [OK]

Common Mistakes:

• Not specifying method attribute causing conflicts
• Checking HTTP method manually inside one method
• Omitting path attribute causing mapping errors