Spring MVC instantiate inner class form bean property - ajax

Question

I have post data like:
cond[startData]:2015-09-22
cond[endDate]:2015-09-23
cond[orderId]:
And my ajax is:
cond={
startDate: "2015-09-22",
endDate: "2015-09-23",
orderId: ""
}
queryData = {cond:cond};
$.ajax({
url: "orderDetail",
type: "post",
dataType:"json",
data: queryData,
success: function(data){
}
});
And my spring form bean is
public class OrderFormBean {
private Cond cond;
private Result result;
// query condition
public class Cond {
private String startDate;
private String endDate;
private String orderId;
}
// query result
public class Result {
private String orderId;
private String orderDate;
private String operator;
...
}
...
}
So, it will cause error:
org.springframework.beans.NullValueInNestedPathException: Invalid property 'cond' of bean class [*.OrderFormBean]: Could not instantiate property type [*.OrderFormBean$Cond] to auto-grow nested property path: java.lang.InstantiationException: *.OrderFormBean$Cond
Edit
I found that even if I post data this way:
queryData = {
"cond.startDate": startDate,
"cond.endDate": endDate,
"cond.balanceType": balanceType,
"cond.orderId": orderId
};
Spring still produces the error Could not instantiate property type [*.OrderFormBean$Cond].
If I move inner class Cond outside, the Spring MVC works.
So It's the inner class reason, that Spring can't instantiate it.
According to this
How to create a Spring Bean of a Inner class?, there is a xml configure. But I don't want to configure it, as OrderFormBean is not configured.

Answer 1

Your error is caused by the field result being null.
Try the following:
cond={
startDate: "2015-09-22",
endDate: "2015-09-23",
orderId: ""
};
result={
/*whatever you are going to write here*/
};
queryData = {
cond: cond,
result: result
};
reference: http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/beans/NullValueInNestedPathException.html
EDIT:
Also, your inner classes cannot be instantiated because non-static inner classes don't have a default (no-arguments) constructor.
Solutions are: either mark your inner classes as static or move them outside your "containing" class (to their own separate .java files)
For more details you can read:
http://thecodersbreakfast.net/index.php?post/2011/09/26/Inner-classes-and-the-myth-of-the-default-constructor