Spring Boot Adding Model to the View with Thymeleaf and MVC - spring-boot

Question

Ok, so I'm trying to put an attribute of an object from the model to the view as a list using thymeleaf, spring boot and jpa, I've been reading over the code for hours and I can't seem to spot my problem, also in the same application I have a very similar function working so I sort of know how to do it, but I just cannot seem to figure out this one. I keep getting an error Property or field 'question' cannot be found on null. I have no idea where I'm going wrong. The object I'm have is called QuestionAnswerSet, and I have a question string and an answer string in the database, that I can submit through the app, so it's not a problem with the database. Also everything is good with my pom file because as I said earlier I have done a very similar function.
Here's my controller.
#Controller
public class QuestionAnswerSetController
{
private QuestionAnswerSetRepository questionAnswerSetRepo;
#RequestMapping("sets")
public String sets (ModelMap model)
{
List<QuestionAnswerSet> questionAnswerSets = questionAnswerSetRepo.findAll();
model.put("questionAnswerSets", questionAnswerSets);
return "sets";
}
#RequestMapping(value="editSet/{questionAnswerSetId}", method=RequestMethod.GET)
public String editSetGet (#PathVariable Long questionAnswerSetId, ModelMap model)
{
return "editCourse";
}
#RequestMapping(value="createSet", method=RequestMethod.GET)
public String createSetGet (ModelMap model)
{
QuestionAnswerSet questionAnswerSet = new QuestionAnswerSet();
model.put("questionAnswerSet", questionAnswerSet);
return "createSet";
}
#RequestMapping(value="createSet", method=RequestMethod.POST)
public String createSetPost (#ModelAttribute QuestionAnswerSet questionAnswerSet, ModelMap model)
{
questionAnswerSetRepo.save(questionAnswerSet);
return "redirect:/sets";
}
#Autowired
public void setQuestionAnserSetRepo(QuestionAnswerSetRepository questionAnserSetRepo) {
this.questionAnswerSetRepo = questionAnserSetRepo;
}
}
Here's my html
<div th:each="Set : ${questionAnswerSets}" th:object="${questionAnswerSet}">
<span th:text="${questionAnswerSet.question}"></span>
</div>
<div th:if="${#lists.isEmpty(questionAnswerSets)}">
There is no sets to display.
</div>
Here's my repository, it's pretty standard, just though I would include it
public interface QuestionAnswerSetRepository extends JpaRepository<QuestionAnswerSet, Long> {
}
And here's my QuestionAnswerSet.java object, which is what I'm trying to return as a list
#Entity
public class QuestionAnswerSet {
private Long id;
private String question;
private String answer;
private User user;
#Id
#GeneratedValue
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getQuestion() {
return question;
}
public void setQuestion(String question) {
this.question = question;
}
public String getAnswer() {
return answer;
}
public void setAnswer(String answer) {
this.answer = answer;
}
#ManyToOne
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
}
And Here's the error in my console
org.springframework.expression.spel.SpelEvaluationException: EL1007E:(pos 0): Property or field 'question' cannot be found on null

Answer 1

Yup, that should be pretty straightforward, here is the exception :
Property or field 'question' cannot be found on null
Spring EL tries to evaluate the below :
<div th:each="Set : ${questionAnswerSets}" th:object="${questionAnswerSet}">
<span th:text="${questionAnswerSet.question}"></span>
</div>
And it is unable to find questionAnswerSet ,which is null hence the error.
Use something like this :
<div th:each="questionAnswerSet : ${questionAnswerSets}">
<span th:text="${questionAnswerSet.question}"></span>
</div>
Refer Doc :
http://www.thymeleaf.org/doc/tutorials/2.1/usingthymeleaf.html#using-theach