Spring Multipart File Upload - spring

Question

I'm trying to upload a MultipartFile using Spring MVC, tomcat, Tyhmleaf but can't get it work.
java.lang.NullPointerException
com.cars.actions.controller.brand.BrandController.persist2(BrandController.java:75)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
java.lang.reflect.Method.invoke(Method.java:483)
My controller:
#RequestMapping(value = "/addimage", method = RequestMethod.POST)
public String persist2( #Valid #ModelAttribute("brand") BrandDTO brandDTO, BindingResult result, RedirectAttributes redirectAttrs, Model model) {
if (result.hasErrors()) {
if (!brandDTO.getFile().isEmpty()) { // null pointer exception
errorNotValid(model, "");
return ADD_PAGE;
} else {
try {
BufferedImage src = ImageIO.read(new ByteArrayInputStream(brandDTO.getFile().getBytes()));
File destination = new File("/Users/katsu/Desktop/file/");
ImageIO.write(src, "png", destination);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
try {
Brand brand = getEntity(brandDTO);
service.save(brand);
successAddMesage(model, "succes");
model.addAttribute(businessObject, new Brand());
return ADD_PAGE;
} catch (DuplicateItemFoundException e) {
errorDuplicateMessage(redirectAttrs, "dublucate");
return REDIRECT_LIST_PAGE;
}
}
}
My DTO:
public class BrandDTO {
private Integer id;
private String name;
private boolean enabled;
private CommonsMultipartFile file;
Apliaiton iniliaze:
public class ApplicationInitializer implements WebApplicationInitializer {
#Override
public void onStartup(ServletContext servletContext) throws ServletException {
// Register the Root application context
AnnotationConfigWebApplicationContext rootContext = new AnnotationConfigWebApplicationContext();
rootContext.register(RootConfig.class);
// Register the Web application context
AnnotationConfigWebApplicationContext mvcContext = new AnnotationConfigWebApplicationContext();
mvcContext.register(WebAppConfig.class);
// Context loader listener
//servletContext.addListener(new ContextLoaderListener(rootContext));
// Register the Dandelion filter
FilterRegistration.Dynamic dandelionFilter = servletContext.addFilter("dandelionFilter", new DandelionFilter());
dandelionFilter.addMappingForUrlPatterns(null, false, "/*");
// Register the Spring dispatcher servlet
ServletRegistration.Dynamic dispatcher = servletContext.addServlet("springServlet", new DispatcherServlet(mvcContext));
dispatcher.setLoadOnStartup(1);
dispatcher.addMapping("/");
//dispatcher.setMultipartConfig(rootContext.getBean(Multi));
// Register the Dandelion servlet
ServletRegistration.Dynamic dandelionServlet = servletContext.addServlet("dandelionServlet",new DandelionServlet());
dandelionServlet.setLoadOnStartup(2);
dandelionServlet.addMapping("/dandelion-assets/*");
}
My Web initialize:
#Bean
public CommonsMultipartResolver multipartResolver() {
CommonsMultipartResolver resolver=new CommonsMultipartResolver();
resolver.setDefaultEncoding("utf-8");
resolver.setMaxUploadSize(40000000);
return resolver;
}
My Form:
<form class="mainForm" action="#" data-th-action="#{/admin/brand/addimage}" data-th-object="${brand}" method="post" accept-charset="utf-8" enctype="multipart/form-data">
<!-- Input text fields -->
<fieldset>
<div class="widget first">
<div class="head">
<h5 class="iList">Marka Ekleme</h5>
</div>
<div class="rowElem">
<label>Marka Adı:</label>
<div class="formRight">
<input type="text" placeholder="adını giriniz" data-th-value="*{name}" data-th-field="*{name}" />
<span th:if="${#fields.hasErrors('name')}" th:errors="*{name}">Name Error</span>
</div>
<div class="fix"></div>
</div>
<div class="rowElem">
<label>Marka Logo:</label>
<div class="formRight">
<input type="file" data-th-field="*{file}"/>
</div>
<div class="fix"></div>
</div>
<div class="rowElem">
<label>Aktif Mi:</label>
<div class="formRight">
<select class="select2" title="Click to Select a City" th:field="*{enabled}">
<option th:each="type : ${enabledOptions}" th:value="${type}" th:text="${type}">Dropdown</option>
</select>
</div>
<div class="fix"></div>
</div>
<input type="submit" value="Submit form" class="greyishBtn submitForm" />
<div class="fix"></div>
</div>
</fieldset>
</form>
and last tomcat permission:
<Context allowCasualMultipartParsing="true">
I digging all internet but cant resolve this problem. whats my wrong?

Answer 1

Try to replace
#ModelAttribute BrandDTO brandDTO
with
#ModelAttribute("brand") BrandDTO brandDTO
Currently your controller expects a model attribute named "brandDTO" which is null since without explicit naming it is derived from the argument type. But in your form you set a data-th-object=${brand}.
If instead you keep the brandDTO name for the attribute and rename your th object in the page you better change :
data-th-field="${brand.file}"
to:
data-th-field="*{file}"