Spring MVC File Upload with multipart data and unit test - unit-testing

Question

I am using Spring 4 latest, and I generally have no problem writing RESTful controllers. There is a legacy web-app, which is using java.net.HTTPUrlConnection to do a multi-part upload. There are 3 pieces of data we are uploading:
1 is a PDF file, and we have the bytes, then the other two pieces of data are just 2 string fields.
First let me show you the Spring REST controller to accept the data:
#RequestMapping(value = "/save", method = RequestMethod.POST, produces = "application/json", consumes = "multipart/form-data")
public #ResponseBody boolean saveData(#RequestPart(value = "field1") String field1, #RequestPart(value = "field2") String field2, #RequestParam(value = "pdfbytes") String pdfbytes)
{
System.out.println("saveData: field1=" + field1);
System.out.println("saveData: field2=" + field2);
System.out.println("saveData: pdfbytes=" + pdfbytes);
boolean response = true;
return response;
}
The code in front-end, for sending the data using 'java.net.HttpURLConnection'
looks like this:
String boundary = MultiPartFormOutputStream.createBoundary();
URL uploadDocumentUrl = new URL(protocol + "://" + host + UPLOAD_EDITED_DOCUMENT);
HttpURLConnection urlConn = (HttpURLConnection) MultiPartFormOutputStream.createConnection(uploadDocumentUrl);
urlConn.setRequestProperty("Content-Type", MultiPartFormOutputStream.getContentType(boundary));
urlConn.setRequestProperty("Connection", "Keep-Alive");
urlConn.setRequestProperty("Cache-Control", "no-cache");
urlConn.setRequestProperty("User-Agent", userAgent);
urlConn.setRequestMethod("POST");
MultiPartFormOutputStream out = new MultiPartFormOutputStream(urlConn.getOutputStream(), boundary);
String pdfbytes= getEncodedDocument(pdf);
out.writeField("field1", field1);
out.writeField("field2", field2);
out.writeField("pdfbytes", pdfbytes);
out.close();
int responseCode = urlConn.getResponseCode();
String responseMessage = urlConn.getResponseMessage();
"MultiPartFormOutputStream" is a custom object that was created to send data via HttpUrlConnection, it's pretty standard code. I do trust it at this time.
So, based on how we are sending the data, do I need to change the Controller to do anything different, or does that look ok?
Now here is the code, that I am using to Unit Test that controller:
#Test
public void testMockUpload() throws Exception
{
// Load resource being uploaded
byte[] pdfbytes = getByteArrayFromFile(FILENAME);
MockMultipartFile firstFile = new MockMultipartFile("field1", "", "text/plain", "field1 data".getBytes());
MockMultipartFile secondFile = new MockMultipartFile("field2", "", "text/plain", "field2 data".getBytes());
MockMultipartFile jsonFile = new MockMultipartFile("pdfbytes", "", "text/plain", pdfbytes);
MockHttpServletRequestBuilder requestBuilder = MockMvcRequestBuilders.fileUpload(BASE_URL + "/save").file(firstFile).file(secondFile).file(jsonFile)
.with(user(USERNAME).roles("role1", "role2")).contentType(MediaType.MULTIPART_FORM_DATA_VALUE);
this.mockMvc.perform(requestBuilder).andDo(print()).andExpect(status().isOk());
}
And the error I get back now, is:
org.springframework.web.method.annotation.MethodArgumentConversionNotSupportedException
which I am looking into. If I need to make any changes on how I need to create my test, I am very open to that. Eventually, I will get everything to sync up between the sending code, the receiving controller, and the unit test.
Thanks in advance! As usual, if there is any other data, or information, I can provide, please let me know. Thanks!

Answer 1

To upload one file you would define the RequestParam type as org.springframework.web.multipart.MultipartFile;
#RequestMapping(value = "/save", method = RequestMethod.POST, produces = "application/json", consumes = "multipart/form-data")
public #ResponseBody boolean saveData(#RequestParam(value = "file") MultipartFile file)
{
return response;
}
For Multiple files I'd try creating a Wrapper form:
public class UploadForm{
private List<MultipartFile> files;
}
Bind to this in the controller:
#RequestMapping(value = "/save", method = RequestMethod.POST, produces = "application/json", consumes = "multipart/form-data")
public #ResponseBody boolean saveData(#ModelAttribute uploadForm)
{
return response;
}
and then use Spring's support for indexed fields to bind to a collection:
Test:
MockMultipartFile firstFile = new MockMultipartFile("files[0]", "", "text/plain", "field1 data".getBytes());
MockMultipartFile secondFile = new MockMultipartFile("files[1]", "", "text/plain", "field2 data".getBytes());
MockMultipartFile jsonFile = new MockMultipartFile("files[2]", "", "text/plain", pdfbytes);
Client:
out.writeField("files[0]", file1Bytes);
out.writeField("files[1]", file2Bytes);
...