Should I use singleton or create new object for each request?

[chaitanya karthikk]

Hi all, I am having an ajax controller. This controller will receive post data. I am validating the post data and then if it has some errors I am sending the errors as a json object.

The error messages, codes are in the BindingResult. So I created a new class called JsonValidatedResponse. In this class I am extracting the error codes and fields and adding them to appropriate lists. Then sending the marshaled object to client.

My doubt is should if I want to autowire this JsonValidatedResponse object, which scope should I use? Request scope or singleton scope? However I am not creating any session to have session scope.

As I see request scope is what I need I think so. Can anyone please suggest me? This is how my JsonValidatedResponse looks like

public JsonValidationResponse(MessageSource messageSource, BindingResult result) {
	errorMessage = new ArrayList<String>();
	errorField = new ArrayList<String>();
	for(ObjectError error: result.getAllErrors()) {
		errorMessage.add(messageSource.getMessage(error, null));
	}
	for(FieldError error: result.getFieldErrors()) {
		errorField.add(error.getField());
	}
}
public List<String> getErrorMessage() {
	return errorMessage;
}
public List<String> getErrorField() {
	return errorField;
}

This is what I am doing in the controller

return new JsonValidationResponse(messageSource, result);

[Paul Clapham]

You shouldn't use a singleton unless there's an extremely good reason to do so.

You don't appear to have an extremely good reason. Or any reason for that matter. At least you haven't posted any... Does that help?

[Bill Gorder]

This is in essence a DTO (data transfer object). Its sole purpose is to pass information from your controller to your view. Typically I would not make these type of objects Spring beans. In any object though it is good practice to make your fields private unless there is a good reason not to (currently they are package private).

[chaitanya karthikk]

Thank you Mr.Bill. I will create a new Object for every request.