[FIXED] Spring Boot file upload doesn't work (bad request)

Issue

I'm trying to do a simple file upload via a Rest API created with Spring Boot and Kotlin. This is my code:

@RestController
@RequestMapping("/api")
class Controller {

    @PostMapping("/upload")
    fun handleFileUpload(@RequestParam("file") file: MultipartFile): ResponseEntity<String> {
        try {
            file.transferTo(File("C:\\upload\\" + file.originalFilename))
        }
        catch (e: Exception) {
            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).build()
        }
        return ResponseEntity.ok("File uploaded successfully.")
    }

}

When I use Postman to test it, I get the status "400 Bad Request".

I'm using a Post-Request with the URL http://localhost:8080/api/upload. In the Header Section I left everything how it is (I read somewhere that the Content-Type Header sometimes causes trouble and therefore turned it off temporarily but this didn't help). In the Body section I chose "form-data", added a key called "file" and selected my test-file as a value.

What am I doing wrong?

Solution

Try to check your configuration, in particular if you have in the application.yml or application.properties the following:

spring.servlet.multipart.enabled=true
spring.servlet.multipart.location=${java.io.tmpdir}

And also in your pom.xml or build.gradle the dependency:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
    <version>2.6.1</version>
</dependency>

You can get some inspiration from this tutorial: https://www.baeldung.com/spring-file-upload

Answered By - cdr89
Answer Checked By - Robin (JavaFixing Admin)