EL1007E: свойство или поле 'текст' не может быть найдено в null

Question

Когда я пытался открыть страницу, появляется ошибка: EL1007E: Свойство или поле 'text' не может быть найдено в null

Текст ошибки

    at org.thymeleaf.spring5.expression.SPELVariableExpressionEvaluator.evaluate(SPELVariableExpressionEvaluator.java:290)
    at org.thymeleaf.standard.expression.SelectionVariableExpression.executeSelectionVariableExpression(SelectionVariableExpression.java:158)
    at org.thymeleaf.standard.expression.SimpleExpression.executeSimple(SimpleExpression.java:92)
    at org.thymeleaf.standard.expression.Expression.execute(Expression.java:109)
    at org.thymeleaf.standard.expression.Expression.execute(Expression.java:138)
    at org.thymeleaf.standard.processor.AbstractStandardExpressionAttributeTagProcessor.doProcess(AbstractStandardExpressionAttributeTagProcessor.java:144)
    at org.thymeleaf.processor.element.AbstractAttributeTagProcessor.doProcess(AbstractAttributeTagProcessor.java:74)
    at org.thymeleaf.processor.element.AbstractElementTagProcessor.process(AbstractElementTagProcessor.java:95)
    at org.thymeleaf.util.ProcessorConfigurationUtils$ElementTagProcessorWrapper.process(ProcessorConfigurationUtils.java:633)
    at org.thymeleaf.engine.ProcessorTemplateHandler.handleStandaloneElement(ProcessorTemplateHandler.java:918)
    at org.thymeleaf.engine.StandaloneElementTag.beHandled(StandaloneElementTag.java:228)
    at org.thymeleaf.engine.Model.process(Model.java:282)
    at org.thymeleaf.engine.ProcessorTemplateHandler.handleOpenElement(ProcessorTemplateHandler.java:1587)
    at org.thymeleaf.engine.OpenElementTag.beHandled(OpenElementTag.java:205)
    at org.thymeleaf.engine.Model.process(Model.java:282)
    at org.thymeleaf.engine.ProcessorTemplateHandler.handleOpenElement(ProcessorTemplateHandler.java:1587)
    at org.thymeleaf.engine.OpenElementTag.beHandled(OpenElementTag.java:205)
    at org.thymeleaf.engine.Model.process(Model.java:282)
    at org.thymeleaf.engine.Model.process(Model.java:290)
    at org.thymeleaf.engine.GatheringModelProcessable.process(GatheringModelProcessable.java:78)
    at org.thymeleaf.engine.ProcessorTemplateHandler.handleCloseElement(ProcessorTemplateHandler.java:1640)
    at org.thymeleaf.engine.TemplateHandlerAdapterMarkupHandler.handleCloseElementEnd(TemplateHandlerAdapterMarkupHandler.java:388)
    at org.thymeleaf.templateparser.markup.InlinedOutputExpressionMarkupHandler$InlineMarkupAdapterPreProcessorHandler.handleCloseElementEnd(InlinedOutputExpressionMarkupHandler.java:322)
    at org.thymeleaf.standard.inline.OutputExpressionInlinePreProcessorHandler.handleCloseElementEnd(OutputExpressionInlinePreProcessorHandler.java:220)
    at org.thymeleaf.templateparser.markup.InlinedOutputExpressionMarkupHandler.handleCloseElementEnd(InlinedOutputExpressionMarkupHandler.java:164)
    at org.attoparser.HtmlElement.handleCloseElementEnd(HtmlElement.java:169)
    at org.attoparser.HtmlMarkupHandler.handleCloseElementEnd(HtmlMarkupHandler.java:412)
    at org.attoparser.MarkupEventProcessorHandler.handleCloseElementEnd(MarkupEventProcessorHandler.java:473)
    at org.attoparser.ParsingElementMarkupUtil.parseCloseElement(ParsingElementMarkupUtil.java:201)
    at org.attoparser.MarkupParser.parseBuffer(MarkupParser.java:725)
    at org.attoparser.MarkupParser.parseDocument(MarkupParser.java:301)
    ... 86 more
Caused by: org.springframework.expression.spel.SpelEvaluationException: EL1007E: Property or field 'text' cannot be found on null
    at org.springframework.expression.spel.ast.PropertyOrFieldReference.readProperty(PropertyOrFieldReference.java:213)
    at org.springframework.expression.spel.ast.PropertyOrFieldReference.getValueInternal(PropertyOrFieldReference.java:104)
    at org.springframework.expression.spel.ast.PropertyOrFieldReference.getValueInternal(PropertyOrFieldReference.java:91)
    at org.springframework.expression.spel.ast.SpelNodeImpl.getValue(SpelNodeImpl.java:112)
    at org.springframework.expression.spel.standard.SpelExpression.getValue(SpelExpression.java:337)
    at org.thymeleaf.spring5.expression.SPELVariableExpressionEvaluator.evaluate(SPELVariableExpressionEvaluator.java:263)

Контроллер

    public String main(@RequestParam(required = false, defaultValue = "") String filter, Model model){
        Iterable<Message> messages = null;

        if(filter != null && !filter.isEmpty()){
            messages = messageRepo.findByTag(filter);
        } else {
            messages = messageRepo.findAll();
        }

        model.addAttribute("messages", messages);
        model.addAttribute("filter", filter);

        return "main";
    }

    @PostMapping ("/main")
    public String add(
            @AuthenticationPrincipal User user,
            @Valid Message message,
            BindingResult bindingResult,
            @RequestParam("file") MultipartFile file, Model model) throws IOException {
        message.setAuthor(user);

        if(bindingResult.hasErrors()){
            Map<String, String> errorsMap = ControllerUtils.getErrors(bindingResult);
            model.mergeAttributes(errorsMap);

            model.addAttribute("newMessage", message);
        } else {
            if (file != null && !file.getOriginalFilename().isEmpty()) {
                File uploadDir = new File(uploadPath);

                if (!uploadDir.exists()) {
                    uploadDir.mkdir();
                }

                String uuidFile = UUID.randomUUID().toString();
                String resultFilename = uuidFile + "." + file.getOriginalFilename();

                file.transferTo(new File(uploadPath + "/" + resultFilename));

                message.setFilename(resultFilename);
            }

            messageRepo.save(message);
        }

        Iterable<Message> messages = messageRepo.findAll();
        model.addAttribute("messages", messages);

        return "main";
    }

Просмотр

    <div class="collapse" id="collapseExample">
        <div class="form-group mt-3">
            <form method="post" enctype="multipart/form-data" th:object="${newMessage}">
                <input type="text" name="text" class="form-control" placeholder="Enter your Message" th:field="*{text}" th:value="*{text}"/>
                <div class="invalid-feedback" th:if="${#fields.hasErrors('text')}" th:errors="*{text}"></div>
                <input type="text" name="tag" class="form-control" placeholder="Enter your Tag"/>
                <input type="file" name="file">
                <input type="hidden" name="_csrf" th:value="${_csrf.token}"/>
                <button type="submit" class="btn btn-primary ml-2">Add Message</button>
            </form>
        </div>
    </div>

Bean

@Entity
public class Message {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @NotBlank(message = "Please fill the message")
    @Length(max = 2048, message = "Message too long (more than 2048 symbols)")
    private String text;
    private String tag;

    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "user_id")
    private User author;

    private String filename;

    public Message() {
    }

    public Message(String text, String tag, User author){
        this.text = text;
        this.tag = tag;
        this.author = author;
    }
 ... Getters and Setters...

I попытался добавить атрибут new Message () в основной метод в моем контроллере, а затем открылась страница, но когда я ввожу сообщение в форму и пытаюсь отправить, он показывает мне ту же ошибку