Spring MVC Multipart Request with JSON
This is how I implemented Spring MVC Multipart Request with JSON Data.
Multipart Request with JSON Data (also called Mixed Multipart):
Based on RESTful service in Spring 4.0.2 Release, HTTP request with the first part as XML or JSON formatted data and the second part as a file can be achieved with @RequestPart. Below is the sample implementation.
Java Snippet:
Rest service in Controller will have mixed @RequestPart and MultipartFile to serve such Multipart + JSON request.
@RequestMapping(value = "/executesampleservice", method = RequestMethod.POST, consumes = {"multipart/form-data"})@ResponseBodypublic boolean executeSampleService( @RequestPart("properties") @Valid ConnectionProperties properties, @RequestPart("file") @Valid @NotNull @NotBlank MultipartFile file) { return projectService.executeSampleService(properties, file);}
Front End (JavaScript) Snippet:
Create a FormData object.
Append the file to the FormData object using one of the below steps.
- If the file has been uploaded using an input element of type "file", then append it to the FormData object.
formData.append("file", document.forms[formName].file.files[0]);
- Directly append the file to the FormData object.
formData.append("file", myFile, "myfile.txt");
ORformData.append("file", myBob, "myfile.txt");
- If the file has been uploaded using an input element of type "file", then append it to the FormData object.
Create a blob with the stringified JSON data and append it to the FormData object. This causes the Content-type of the second part in the multipart request to be "application/json" instead of the file type.
Send the request to the server.
Request Details:
Content-Type: undefined
. This causes the browser to set the Content-Type to multipart/form-data and fill the boundary correctly. Manually setting Content-Type to multipart/form-data will fail to fill in the boundary parameter of the request.
Javascript Code:
formData = new FormData();formData.append("file", document.forms[formName].file.files[0]);formData.append('properties', new Blob([JSON.stringify({ "name": "root", "password": "root" })], { type: "application/json" }));
Request Details:
method: "POST",headers: { "Content-Type": undefined },data: formData
Request Payload:
Accept:application/json, text/plain, */*Content-Type:multipart/form-data; boundary=----WebKitFormBoundaryEBoJzS3HQ4PgE1QB------WebKitFormBoundaryvijcWI2ZrZQ8xEBNContent-Disposition: form-data; name="file"; filename="myfile.txt"Content-Type: application/txt------WebKitFormBoundaryvijcWI2ZrZQ8xEBNContent-Disposition: form-data; name="properties"; filename="blob"Content-Type: application/json------WebKitFormBoundaryvijcWI2ZrZQ8xEBN--
This must work!
client (angular):
$scope.saveForm = function () { var formData = new FormData(); var file = $scope.myFile; var json = $scope.myJson; formData.append("file", file); formData.append("ad",JSON.stringify(json));//important: convert to JSON! var req = { url: '/upload', method: 'POST', headers: {'Content-Type': undefined}, data: formData, transformRequest: function (data, headersGetterFunction) { return data; } };
Backend-Spring Boot:
@RequestMapping(value = "/upload", method = RequestMethod.POST) public @ResponseBody Advertisement storeAd(@RequestPart("ad") String adString, @RequestPart("file") MultipartFile file) throws IOException { Advertisement jsonAd = new ObjectMapper().readValue(adString, Advertisement.class);//do whatever you want with your file and jsonAd
As documentation says:
Raised when the part of a "multipart/form-data" request identified by its name cannot be found.
This may be because the request is not a multipart/form-data either because the part is not present in the request, or because the web application is not configured correctly for processing multipart requests -- e.g. no MultipartResolver.