ファイル全体をアップロードする前に、ファイルがBoxで受け入れられるかどうかをチェックします。
curl -i -X OPTIONS "https://api.box.com/2.0/files/content" \
     -H "authorization: Bearer <ACCESS_TOKEN>" \
     -H "content-type: application/json" \
     -d '{"name":"Contract.pdf", "parent":{"id":"11446498"}}'await client.uploads.preflightFileUploadCheck({
  name: newFileName,
  size: 1024 * 1024,
  parent: { id: '0' } satisfies PreflightFileUploadCheckRequestBodyParentField,
} satisfies PreflightFileUploadCheckRequestBody);client.uploads.preflight_file_upload_check(
    name=new_file_name, size=1024 * 1024, parent=PreflightFileUploadCheckParent(id="0")
)await client.Uploads.PreflightFileUploadCheckAsync(requestBody: new PreflightFileUploadCheckRequestBody() { Name = newFileName, Size = 1024 * 1024, Parent = new PreflightFileUploadCheckRequestBodyParentField() { Id = "0" } });client.getUploads().preflightFileUploadCheck(new PreflightFileUploadCheckRequestBody.Builder().name(newFileName).size(1024 * 1024).parent(new PreflightFileUploadCheckRequestBodyParentField.Builder().id("0").build()).build())String fileName = "My Doc.pdf";
BoxFolder rootFolder = BoxFolder.getRootFolder(api);
try {
    folder.canUpload(fileName, 98734576);
    // If the file upload would not have succeeded, it will not be attempted
    folder.uploadFile(fileContents, fileName);
} catch (BoxAPIException ex) (
)// Verify that uploading a 200MB file named "Preso.ppt" to folder 12345 would succeed
client.files.preflightUploadFile(
		'12345',
		{
			name: 'Preso.ppt',
			size: 200000000
		},
		null,
		callback
	);{
  "upload_token": "Pc3FIOG9vSGV4VHo4QzAyg5T1JvNnJoZ3ExaVNyQWw6WjRsanRKZG5lQk9qUE1BVQP",
  "upload_url": "https://upload-las.app.box.com/api/2.0/files/content?upload_session_id=1234"
}