Thymeleaf遍历对象列表

Question

我有一个问题，而我遍历Thymeleaf中的对象列表。 这里是我的HTML：

<input th:each="a,iterStatus : currentQuestion.answers" type="radio" name="answer" th:text="${a.answer}" th:value="${iterStatus.index}"></input> 

这里是Controller类：

@RequestMapping(value={ "/exam", "/exam/" }, method = RequestMethod.GET) 
public String exam(Model model){ 

    if (!sessionPreferences.isExamStarted()){ 
     sessionPreferences.setQuestionList(questionService.list(Questions.findAll().paginate(0, 5).loadWith("answers"))); 
     sessionPreferences.setCurrentQuestion(questionService.uniqueObject(Questions.findAll().withId(1L).loadWith("answers"))); 
    } 
    model.addAttribute("currentQuestion", sessionPreferences.getCurrentQuestion()); 
    sessionPreferences.setExamStarted(true); 
    System.out.println("TRUE!"); 
    System.out.println(sessionPreferences.getCurrentQuestion().getAnswers().size()); 
    System.out.println(sessionPreferences.getCurrentQuestion().getAnswers().get(0)); 
    return "exam"; 
} 

这里是SessionPreferences类：

@Component 
@Scope(value="session", proxyMode = ScopedProxyMode.TARGET_CLASS) 
public class SessionPreferences implements Serializable { 

private static final long serialVersionUID = -3875093750700352970L; 

@Setter 
private String displayName; 

@Setter @Getter 
private Question currentQuestion; 

@Getter @Setter 
private boolean examStarted; 

@Getter @Setter 
private Map<Question, Integer> selections = new LinkedHashMap<Question, Integer>(); 

@Getter @Setter 
private List<Question> questionList = new ArrayList<Question>(5); 


public String getDisplayName() { 
    if(StringUtils.isBlank(displayName)){ 
     displayName = SecurityUtils.getLoggedUsername(); 
    } 
    return displayName; 
    } 
} 

而且我们有问题的模型类：

@Entity 
@Table(name = "questions") 
public class Question extends BaseEntity<Long> { 

private static final long serialVersionUID = -7066617446892759711L; 
public static final int DESCRIPTION_MAX_LENGTH = 5120; 
public static final int OPTIONS_MAX_LENGTH = 4 * 5120; 

public Question() { 
}; 

public Question(String questionDescription, List<Answer> answers) { 
    this.questionDescription = questionDescription; 
}; 

@Id 
@GeneratedValue 
@Getter 
@Setter 
private Long id; 

@Getter 
@Setter 
@Column(length = DESCRIPTION_MAX_LENGTH, nullable = false, name = "question_description") 
private String questionDescription; 

@Getter 
@Setter 
@OneToMany(mappedBy = "question", targetEntity = Answer.class, cascade = CascadeType.ALL) 
private List<Answer> answers = new ArrayList<>(); 

@Getter 
@Setter 
@Column(nullable = false, name = "correct_answer_id") 
private Answer correctAnswerIndex; 
} 

得到的答复类：

@Entity 
@Table(name="answers") 
public class Answer extends BaseEntity<Long>{ 

private static final long serialVersionUID = -6119650375719671237L; 

public Answer(){}; 

public Answer(String answer){ 
    this.answer = answer; 
}; 

@Id 
@GeneratedValue 
@Getter @Setter 
private Long id; 

@Getter @Setter 
private String answer; 

@ManyToOne 
@JoinColumn(name = "question_id", updatable=false) 
@Getter @Setter 
private Question question; 

}

DAO层和服务层做工精细，所以它是在回答对象访问字符串的答案，同时使用Thymeleaf迭代问题。

我有以下错误：

SEVERE: Servlet.service() for servlet [spring] in context with path [] threw exception [Request processing failed; nested exception is org.thymeleaf.exceptions.TemplateProcessingException: Exception evaluating SpringEL expression: "a.answer" (exam:99)] with root cause 
    org.springframework.expression.spel.SpelEvaluationException: EL1008E:(pos 2): Field or property 'answer' cannot be found on object of type 'java.lang.String' 

任何想法？

P.S三syso导致：TRUE！4，对象..

Answer 1

有一个在语法th:each属性一个问题，因为currentQuestion.answers应包裹成表情评估（${...}）基团。

正确的版本：

<input th:each="a,iterStatus : ${currentQuestion.answers}" type="radio" name="answer" th:text="${a.answer}" th:value="${iterStatus.index}"></input>