springspring-bootkotlinfile-uploadminio

Spring Not Allowing File Upload (Application-Octet Not Supported)

I'm trying to upload pdfs to MinIO using Kotlin Spring. I've written a controller to upload pdfs:

@PostMapping(consumes = [MediaType.MULTIPART_FORM_DATA_VALUE, MediaType.APPLICATION_OCTET_STREAM_VALUE])
    fun createPaper(
        @RequestPart("metadata") paperRequest: PaperRequest,
        @RequestPart("pdf") pdfFile: MultipartFile
    ): ResponseEntity<Paper>

I'm making the following curl request:

$ curl -X POST http://localhost:8082/api/v1/papers -F "metadata={\"title\":\"Example Research Paper\",\"authors\":[\"Jane Smith\",\"John Doe\"],\"ab
stract\":\"This is a test paper abstract\",\"doi\":\"10.1234/test.123\",\"venue\":\"Test Conference 2024\",\"keywords\":[\"testing\",\"research\"]}" -F "pdf=@paper.pdf;type=application/pdf" -H "Content-Type: multipart/form-data"

However, I keep getting this response:

{"timestamp":"2025-01-07T09:14:36.910+00:00","status":415,"error":"Unsupported Media Type","path":"/api/v1/papers"}

and here's what the spring logs say:

DefaultHandlerExceptionResolver : Resolved [org.springframework.web.HttpMediaTypeNotSupportedException: Content-Type 'application/octet-stream' is not supported]

Why won't it allow me to upload files?
Things I've tried:

Solution

  • The problem is not in the your code, the problem is in the curl.
    Add the Content-Type of application/json to metadata field

    -F "metadata={\"key\": \"value\"};type=application/json"

    Your fixed curl:

    curl -X POST http://localhost:8082/api/v1/papers \
-F "metadata={\"title\":\"Example Research Paper\",\"authors\":[\"Jane Smith\",\"John Doe\"],\"ab
stract\":\"This is a test paper abstract\",\"doi\":\"10.1234/test.123\",\"venue\":\"Test Conference 2024\",\"keywords\":[\"testing\",\"research\"]};type=application/json" \
-F "pdf=@paper.pdf;type=application/pdf"

    Also everything should work even without: