[英]Spring MVC / JSP - How to pass nested list of object to controller from a select form
[英]How to bind nested List object to JSP form?
各位程序员大家好,
我正在编写一个Spring MVC应用程序,供学生进行多项选择题的在线评估。 管理员应该能够创建评估,所以我创建了以下对象结构:
@Entity
@Table(name = "assessment")
public class Assessment {
private List<Question> questions;
// getter and setter
}
@Entity
@Table(name = "question")
public class Question {
private String questionText;
private List<Answer> answers;
// getters and setters
}
@Entity
@Table(name = "answer")
public class Answer {
private String answerText;
private boolean isCorrect;
// getters and setters
}
现在,我在管理页面上使用了JSP表单:
调节器
@RequestMapping(value = "/add/assessment", method = RequestMethod.GET)
public String addAssessments(Model model) {
model.addAttribute("assessmentModel", new Assessment());
return "admin-assessments-create";
}
JSP表格
<form:form method="POST" modelAttribute="assessmentModel">
<form:input path="questions[0].questionText" type="text"/> <!-- this is working-->
<form:radiobutton path="questions[0].answers[0].isCorrect"/> <!-- not working-->
<form:input path="questions[0].answers[0].answerText"/>
<button class="btn" type="submit">Submit</button>
</form:form>
当我转到此页面时,收到以下错误:
org.springframework.beans.NotReadablePropertyException:
Invalid property 'questions[0].answers[0].isCorrect' of bean class [com.johndoe.model.Question]:
Bean property 'questions[0].answers[0].isCorrect' is not readable or has an invalid getter method:
Does the return type of the getter match the parameter type of the setter?
我检查了所有的吸气剂和吸气剂,但都很好。
如何避免NotReadablePropertyException
从而将嵌套的答案列表绑定到表单?
采用
<form:radiobutton path="questions[0].answers[0].correct"/>
它将起作用。
为什么? 对于boolean
字段,您必须将get / set范例修改为"is"XYZ()
。 对于EL表达式,您必须在访问字段的当前值的方法之前放置“ is ”,几乎与“ get” /“ set”相同。
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