Exception

[dull palm]

What kind of exception can i throw if there is nothing about requested thing in my db?
Should i create a new one for myself or there is already such kind of exception to use in spring boot application?

[raven jasper]

<@&1004656351647117403> please have a look, thanks.

Here is an AI assisted attempt to answer your question 🤖. Maybe it helps! In any case, a human is on the way 👍. To continue talking to the AI, you can use </chatgpt:1108714622413963314>.

In Spring Boot, you can throw a NoSuchElementException if there is nothing about the requested thing in your database. This exception is commonly used to indicate that an element does not exist in a collection or database.

You can simply throw this exception in your code like this:

throw new NoSuchElementException("Requested element not found in the database");

There is no need to create a custom exception for this specific case as the NoSuchElementException already serves this purpose.

[worldly island]

You mean what to put inside the HTTP response on a spring application?

or you just want an exception to throw if the select doesn't return any result? in that case NoSuchElementException is a good choice

[gleaming cipher]

And which layer?

An absence does not always need to imply an exceptional circumstance

[dull palm]

yep like this

[dull palm]

this too, I mean i will have a function, you know findById from db?

and then .orElseThrow will throw an exception

or it's not a good idea

Like this:

private Category getByIdOrElseThrow(Long id) {
return categoryRepository.findById(id).orElseThrow(() ->
new NoSuchElementException("Category not found!"));
}

[dull palm]

what do you mean?

[gleaming cipher]

In a Repository you should just return Optional<Category> and not throw an Exception on the absence for example

[dull palm]

okay just a second

[worldly island]

If it is a spring project or anything else that implements HTTP requests then the error should be added in the HTTP response:

ResponseEntity.status(HttpStatus.NOT_FOUND)

If you throw an exception when when you execute your query, then you will have to handle the exception when you call that method and return the thing i've wrote up here

[dull palm]

public ResponseEntity<?> viewOne(Long id) {
Category category = getByIdOrElseThrow(id);
if (category == null) {
return new ResponseEntity<>(HttpStatus.NOT_FOUND);
}
CategoryResDTO categoryResDTO = entityToResDTO(category);
return ResponseEntity.ok(categoryResDTO);
}

private Category getByIdOrElseThrow(Long id) {
Optional<Category> category = categoryRepository.findById(id);
return category.orElse(null);
}

what do you think about it?

or could i do it better?

[dull palm]

what do you think bro

public ResponseEntity<?> viewOne(Long id) {
try {
Category category = getByIdOrElseThrow(id);
CategoryResDTO categoryResDTO = entityToResDTO(category);
return ResponseEntity.ok(categoryResDTO);
} catch (NoSuchElementException ex) {
return new ResponseEntity<>(HttpStatus.NOT_FOUND);
}
}

private Category getByIdOrElseThrow(Long id) {
return categoryRepository.findById(id)
.orElseThrow(() -> new NoSuchElementException("Category not found with id: " + id));
}

or like this?

[gleaming cipher]

getByIdOrElseThrow is a bit odd given you don't throw
And I'd just have the service call throw some flavour of ResourceNotFoundException, and define an exception handler + enable problem details in spring boot.

[dull palm]

you mean handling this exception in Exception Handler class?

[worldly island]

Dude i'm really not understanding what scope is this project placed

based on what you want to achieve throwing an exception or building a response are both methods to handle things that returns something different from what they should, but they have different apply. Http response are used when you need to comunicate the client what is the result of his request, exception are used internally and you will have to handle them by yourself

[gleaming cipher]

you can just use @ExceptionHandler on a method in your controller. But you seem to be jumping layers in your question which is why I asked about it.

[dull palm]

I have Controller interface and class that implements it then service interface with its class

and i wll call service in controller class

[dull palm]

you mean this?

[gleaming cipher]

at times we're talking about controller, at times services, something repository. A bit what tvrsier also mentioned.

[raven jasper]

@dull palm

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[dull palm]

i tried this one

can u tell me if i did something wrong

private Category getByIdOrElseThrow(Long id) {
return categoryRepository.findById(id).orElseThrow(() ->
new NoSuchElementException("Category not found!"));
}

@org.springframework.web.bind.annotation.ExceptionHandler(NoSuchElementException.class)
public HttpEntity<?> handling(NoSuchElementException ex) {
return ResponseEntity
.status(HttpStatus.NOT_FOUND)
.body(ex.getMessage());
}

i got this response from postman:
{
"timestamp": "2024-02-25T09:34:17.069+00:00",
"status": 404,
"error": "Not Found",
"path": "/api/category/view/1"
}