方法调用：尝试在空上下文对象上调用方法

Question

当我加载我的应用程序页面时，我给出下一个异常

 org.thymeleaf.exceptions.TemplateProcessingException: Exception evaluating SpringEL expression: "instructor.user.getUserEmail()" (template: "views/instructorCreate" - line 84, col 6)
Caused by: org.springframework.expression.spel.SpelEvaluationException: EL1011E: Method call: Attempted to call method getUserEmail() on null context object
Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed: org.thymeleaf.exceptions.TemplateProcessingException: Exception evaluating SpringEL expression: "instructor.user.getUserEmail()" (template: "views/instructorCreate" - line 84, col 6)] with root cause

org.springframework.expression.spel.SpelEvaluationException: EL1011E: Method call: Attempted to call method getUserEmail() on null context object

我的版本 Thymeleaf 3.1 和 Spring 6.0.2

我的 Html + Thymeleaf 页面

<div class="mb-3 mt-3">
                <label for="userEmail" class="form-label"> Email :</label>
                <input id="userEmail" type="email" name="userEmail" class="form-control"
                    th:value="${instructor.user.getUserEmail()}" required>
                    <span th:errors="${instructor.user.email}"> </span>
            </div>
            
            <div class="mb-3 mt-3">
                <label for="userPassword" class="form-label"> Password :</label>
                <input id="userPassword" type="text" name="userPassword" class="form-control"
                    th:value="${instructor.user.getUserPassword()}" required>
            </div>

用户获取器

public String getUserEmail() {
        return userEmail;
    }

教师用户领域；

@OneToOne (cascade = CascadeType.REMOVE)
    @JoinColumn (name = "user_id", referencedColumnName = "user_id", nullable = false)
    private User user;

如果你知道我的问题在哪里，我会感谢你

Answer 1

我的控制器

@GetMapping ("/formCreate")
    public String createInstructor(Model model) {
        model.addAttribute("instructor", new Instructor());
        return "views/instructorCreate";
    
    }