Return multiple files from the Spring @PostMapping method

Asked Jul 12 '19 at 15:57

Active Jul 12 '19 at 15:57

Viewed 1,912 times

I upload some files to my PostMapping endpoint, it accepts @RequestParam("files") MultipartFile[] files.

My application performs some logic over them, and I would like to send those images back as blobs. Can I do it with Spring? I have no problem returning 1 file back using the ResponseEntity<byte[]> return type, by just using Files.readAllBytes(myOnlyFile), but I'm not sure how to do so for many files. Perhaps I need to return ResponseEntity<byte[][]>? Thanks in advance.

asked Jul 12 '19 at 15:57

saæ

1

I don't think there's a clean way to do it _with HTTP_. – chrylis -cautiouslyoptimistic- Jul 12 '19 at 16:02
@chrylis, interesting, why wouldn't it be clean? Because of the problems on the client-side, trying to interpret this massive 2d byte array? – saæ Jul 12 '19 at 16:04
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What if we return zip file? – Romil Patel Jul 12 '19 at 16:05
@PatelRomil, will I have to unzip it on the client? Or does JS do it automatically? My client gets the result from an async `POST` request to the Spring endpoint. – saæ Jul 12 '19 at 16:06
No, because there's no way in HTTP to express multiple downloads in a way that any client will understand. The closest is something like a no-compression ZIP file. Otherwise, send one file at a time. – chrylis -cautiouslyoptimistic- Jul 12 '19 at 16:07
thanks @chrylis, I think I'll try the ZIP file then! – saæ Jul 12 '19 at 16:09
Do you want to display those images immediately after posting/saving – Romil Patel Jul 12 '19 at 16:13
@PatelRomil I think I'd like to show them as soon as they arrive. – saæ Jul 12 '19 at 16:15
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I think you have to unzip it on a client to show them. you can refer this https://stackoverflow.com/questions/2095697/unzipping-files – Romil Patel Jul 12 '19 at 16:20

Return multiple files from the Spring @PostMapping method

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