Recommend using containers' default multipart upload support rather than CommonsMultipartResolver

[darshanmehta10]

Here's the method to upload the file:

@RequestMapping(consumes = "multipart/form-data", method = RequestMethod.POST, 
        value = "/scan", produces = MediaType.APPLICATION_JSON_VALUE)
public String scan(MultipartFile file){
      //code
}

Bean configuations:

@Bean
public CommonsMultipartResolver multipartResolver() {
    return new CommonsMultipartResolver();
}

@Bean
public MultipartConfigElement multipartConfigElement() {
    MultipartConfigFactory factory = new MultipartConfigFactory();
    factory.setMaxFileSize("500MB");
    factory.setMaxRequestSize("500MB");
    return factory.createMultipartConfig();
}

pom.xml:

<parent>
    <groupId>org.springframework.boot\</groupId>
    <artifactId\>spring-boot-starter-parent\</artifactId>
    <version>1.1.8.RELEASE\</version>
</parent>

Request:

POST /scan HTTP/1.1
Host: localhost:9080
Cache-Control: no-cache

----WebKitFormBoundaryE19zNvXGzXaLvS5C
Content-Disposition: form-data; name="file"; filename="generate.png"
Content-Type: image/png


----WebKitFormBoundaryE19zNvXGzXaLvS5C

• When run with spring boot 1.1.8, it works fine. Method parameter is correctly bound to the value.
• When run with any other version (tried with 1.2.0, 1.2.3), method parameter is always set to null.
  If I modify the method to include Request param like below:

public String scan(@RequestParam("file") MultipartFile file){

It throws an exception saying 'Required MultipartFile parameter 'file' is not present'.

I am running my spring boot app with embedded tomcat.

[wilkinsona]

The problem's specific to the use of CommonsMultipartResolver. Removing the bean and using the auto-configured StandardServletMultipartResolver or explicitly declaring a StandardServletMultipartResolver bean works around the problem.

[wilkinsona]

It only works in 1.1.8 because of the bug reported in #1857. That bug causes the CommonsMultipartResolver bean that's named multipartResolver to be overridden with Boot's own multipartResolver bean that's a StandardServletMultipartResolver.

[wilkinsona]

The problem is that, when you use CommonsMultipartResolver, it's vital that the multipart request is processed before any request parameters are read. Spring Boot auto-configures HiddenHttpMethodFilter and, as noted in its javadoc, it "needs to run after multipart processing in case of a multipart POST request, due to its inherent need for checking a POST body parameter". This can be achieved by declaring a MultipartFilter bean that's ordered to run before HiddenHttpMethodFilter and giving it a filterMultipartResolver bean to use:

@Bean
public CommonsMultipartResolver filterMultipartResolver() {
    return new CommonsMultipartResolver();
}

@Bean
@Order(0)
public MultipartFilter multipartFilter() {
    return new MultipartFilter();
}

[darshanmehta10]

Hi Wilkinsona,
Thanks for the detailed explanation. Will try with StandardServletMultipartResolver bean.
Cheers

[fxulusoy]

@wilkinsona I have the same problem. My method parameter is always set to null. As you said, I set order for the multipartFilter bean but it did not help. I see that HiddenHttpMethodFilter is always called before MultipartFilter. I am using Spring Boot version 1.3.0.RELEASE and Java based config. How can I set the order that HiddenHttpMethodFilter comes after MultipartFilter?

    @Bean(name = "multipartResolver")
    public CommonsMultipartResolver multipartResolver() {
        CommonsMultipartResolver resolver = new CommonsMultipartResolver();        
        resolver.setMaxUploadSizePerFile(52428800); 
        return resolver;
    }

    @Bean
    @Order(0)
    public MultipartFilter multipartFilter() {
            MultipartFilter multipartFilter = new MultipartFilter();
        multipartFilter.setMultipartResolverBeanName("multipartResolver");
        return multipartFilter;
    }
    @RequestMapping(value = "/{userId}", method = RequestMethod.POST)
    @ResponseBody
    public FileTransport createAsset(@PathVariable("userId") Long userId,
            MultipartFile file) throws IOException {
        //return fileService.create(userId, file);
        return new FileTransport();
    }

[wilkinsona]

@fxulusoy The order of HiddenHttpMethodFilter has changed. You need to order your MultipartFilter with a value that's less than -10000.

[fxulusoy]

@wilkinsona Are you sure that will change the order? Because I have tried that and HiddenHttpMethodFilter is still called before MultipartFilter. file argument is still null.

[wilkinsona]

It should work. Perhaps you can share a complete sample project that shows the problem as it's hard to know what's wrong from the little you've shared thus far. A question on Stack Overflow with a complete, minimal example of the problem would be ideal. You can use the spring-boot tag to make sure that we see it.

[wilkinsona]

@fxulusoy I see you've already posted to Stack Overflow: http://stackoverflow.com/questions/37951569/multipartfile-is-null-when-i-use-commonsmultipartresolver-in-my-spring-boot-app. Please don't cross-post, particularly without making it clear that you have done so, as it just wastes people's time.