[FIXED] How to return File downloaded as DataBuffer

Issue

I am downloading a file like below:

private File downloadAndReturnFile(String fileId, String destination) {
    log.info("Downloading file.. " + fileId);
    Path path = Paths.get(destination);
    Flux<DataBuffer> dataBuffer = webClient.get().uri("/the/download/uri/" + fileId + "").retrieve()
            .bodyToFlux(DataBuffer.class)
            .doOnComplete(() -> log.info("{}", fileId + " - File downloaded successfully"));
    
    //DataBufferUtils.write(dataBuffer, path, StandardOpenOption.CREATE).share().block();
    
    return ???? // What should I do here to return above DataBuffer as file? 
}

How can I return the dataBuffer as a File? Or, how can I convert this dataBuffer to a File object?

Solution

You could use DataBufferUtils.write method. To do that, you should

1. instantiate a File object (maybe using fileId and destination) which is also the return value you want
2. create OutputStream or Path or Channels object from the File object
3. call DataBufferUtils.write(dataBuffer, ....).share().block() to write the DataBuffer into the file

viz. (all thrown exceptions are omitted),

...
File file = new File(destination, fileId);
Path path = file.toPath();
DataBufferUtils.write(dataBuffer, path, StandardOpenOption.CREATE).share().block();
return file;

Or,

...
Path path = Paths.get(destination);
DataBufferUtils.write(dataBuffer, path, StandardOpenOption.CREATE).share().block();
return path.toFile();

Answered By - Tonny Tc