Spring Boot App throwing a strange exception

Question

I am following a tutorial and everything seems to work for the author but not for me. The purpose of the use case is to add a new category (id, name, image and a boolean value).
Category entity:

@Entity
@AllArgsConstructor
@NoArgsConstructor
@Getter
@Setter
public class Category {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    private String name;
    private String image;
    private Boolean isActive;
}

Here my controller:

@PostMapping("/admin/category/add")
public String saveCategory(@ModelAttribute Category category, @RequestParam("image") MultipartFile file,
        HttpSession session) throws IOException {

    String imageName = file != null ? file.getOriginalFilename() : "default.jpg";
    category.setImage(imageName);

    Boolean existCategory = categoryService.existCategory(category.getName());

    if (existCategory) {
        session.setAttribute("errorMsg", "Category Name already exists");
    } else {

        Category saveCategory = categoryService.save(category);

        if (ObjectUtils.isEmpty(saveCategory)) {
            session.setAttribute("errorMsg", "Not saved ! internal server error");
        } else {

            File saveFile = new ClassPathResource("static/img").getFile();

            Path path = Paths.get(saveFile.getAbsolutePath() + File.separator + "category_img" + File.separator
                    + file.getOriginalFilename());

            // System.out.println(path);
            Files.copy(file.getInputStream(), path, StandardCopyOption.REPLACE_EXISTING);

            session.setAttribute("succMsg", "Saved successfully");
        }
    }

    return "redirect:/admin/category";
}

And here the view:

<form action="/admin/category/add" method="post" enctype="multipart/form-data">
                                <div class="mb-3">
                                    <label>Enter Category</label> <input type="text" name="name" class="form-control">
                                </div>

                                <div class="mb-3">
                                    <label>Status</label>

                                    <div class="form-check">
                                        <input class="form-check-input" type="radio" checked
                                            value="true" name="isActive" id="flexRadioDefault1">
                                        <label class="form-check-label" for="flexRadioDefault1">
                                            Active </label>
                                    </div>
                                    <div class="form-check">
                                        <input class="form-check-input" type="radio" name="isActive"
                                            value="false" id="flexRadioDefault2"> <label
                                            class="form-check-label" for="flexRadioDefault2">
                                            Inactive </label>
                                    </div>

                                </div>

                                <div class="mb-3">
                                    <label>Upload Image</label> <input type="file" name="image"
                                        class="form-control">
                                </div>
                                <button class="btn btn-primary col-md-12 mt-2">Save</button>
                            </form>

I am receiving the following exception:

There was an unexpected error (type=Bad Request, status=400).

Validation failed for object='category'. Error count: 1 org.springframework.web.bind.MethodArgumentNotValidException: Validation failed for argument [0] in public java.lang.String com.sap.Shopping.Cart.controller.AdminController.saveCategory(com.sap.Shopping.Cart.model.Category,org.springframework.web.multipart.MultipartFile,jakarta.servlet.http.HttpSession) throws java.io.IOException: [Field error in object 'category' on field 'image': rejected value [org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile@73eb957e]; codes [typeMismatch.category.image,typeMismatch.image,typeMismatch.java.lang.String,typeMismatch]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [category.image,image]; arguments []; default message [image]]; default message [Failed to convert property value of type 'org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile' to required type 'java.lang.String' for property 'image'; Cannot convert value of type 'org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile' to required type 'java.lang.String' for property 'image': no matching editors or conversion strategy found]] at org.springframework.web.method.annotation.ModelAttributeMethodProcessor.resolveArgument(ModelAttributeMethodProcessor.java:158) at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:122) at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:224) at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:178) at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:118) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:926) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:831) at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1089) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:979) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1014) at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:914) at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:590) at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:885) at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:658) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:195) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140) at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140) at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140) at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:167) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:90) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:483) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:115) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:93) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:344) at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:384) at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:63) at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:905) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1741) at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52) at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1190) at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:63) at java.base/java.lang.Thread.run(Thread.java:833)

As the error is saying, there is type mismatch issue for the image, but I couldn't figure out what to change exactly.

Answer 1

Your Category object contains an image field that conflicts with the form's multipart image parameter. Change the field name in the Category object to imageName to resolve the issue.