CODEWITHSUNDEEP
springspring-annotationsnotnull
Burakhan Aksoy
Burakhan Aksoy

Reputation: 323

@NotNull annotation is not working in spring boot

I am new to Spring Boot and I have this problem.

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and I still get 200 OK even though I don't provide "data"

enter image description here

Why do you think this is happening?

Any Help is appreciated.

Best

Upvotes: 1

Views: 12738

Answers (2)

silentsudo
silentsudo

Reputation: 6963

You should use @RequestParam as opposed to @PathParams in this case. But validation can also be applied to @PathParam

@GetMapping(path = "extra")
public String doExtraThing(@RequestParam("data") String data) {
    return "Data is: " + data;
}

Using @NotNull

If you hit this api directly from browser

http://localhost:8080/demo/extra

You should get something in the console, because your default request parameter is mandatory.

2021-03-06 08:55:20.872  WARN 2936 --- [nio-8080-exec-1] .w.s.m.s.DefaultHandlerExceptionResolver : Resolved [org.springframework.web.bind.MissingServletRequestParameterException: Required String parameter 'data' is not present]

To make it optional use

@RequestParam(value = "data", required = false) String data

Now when you try to hit http://localhost:8080/demo/extra?data=, you should get

Data is:

Now, when you make it required = false and add @NotNull annotation from javax.validation.constraints package and hit the api again you should get 503 internal server error.

javax.validation.ConstraintViolationException: doExtraThing.data: must not be null

Using @NotBlank:

You can achieve the same behavior using @NotBlank from javax.validation.constraints

@NotNull Validate that the object is not null.

@NotBlank check for character sequence's (e.g. string) trimmed length is not empty.

You would use @NotBlank on strings more here

Upvotes: 1

Amr Saeed
Amr Saeed

Reputation: 305

When you use @NotNull you're preventing String data to have a null value. But in postman when you're sending data with an empty value, you're actually sending it with an empty String "". To prevent both null values and empty strings use @NotBlank.

@RestController
@Validated
public class HelloController {

    @GetMapping(value = "/path")
    public String getData(@Valid @PathParam("data") @NotBlank String data) {
        return data;
    }
}

If you want to send data as null to check if @NotNull works, just uncheck it from the postman params (Don't send it). It should raise an exception in your application that data cannot be null.

Upvotes: 1

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