Validating a form if we have two model object data - spring-mvc

Question

Usually i have seen a server side validation in spring mvc like this for example there is customer page which contains customer related information like customerName ,customerAddress,customerPhoneNumber for this we going to have
customer model object then in the spring controller we are going to call like this
Spring Controller
#RequestMapping(value = "/customerRegistrationScreen")
public String customerRegistrationScreen(Model model) {
Customer customer= new Customer();
model.addAttribute("customer", customer);
return "customerRegistrationScreen";
}
#RequestMapping(value = "/doCustomerRegistration", method = RequestMethod.POST)
public ModelAndView registerCustomer(#ModelAttribute("customer") #Validated Customer customer, BindingResult result,Model model) {
if (result.hasErrors()) {
} else {
}
}
CustomerValidator class
#Component
public class CustomerValidator implements Validator {
#Override
public boolean supports(Class<?> clazz) {
return Customer.class.equals(clazz);
}
#Override
public void validate(Object obj, Errors err) {
ValidationUtils.rejectIfEmpty(err, "name", "customer.name.empty");
ValidationUtils.rejectIfEmpty(err, "email", "customer.email.empty");
ValidationUtils.rejectIfEmpty(err, "gender", "customer.gender.empty");
ValidationUtils.rejectIfEmpty(err, "languages", "customer.languages.empty");
User user = (User) obj;
Pattern pattern = Pattern.compile("^[A-Z0-9._%+-]+#[A-Z0-9.-]+\\.[A-Z]{2,6}$",
Pattern.CASE_INSENSITIVE);
if (!(pattern.matcher(customer.getEmail()).matches())) {
err.rejectValue("email", "user.email.invalid");
}
}
}
customerRegistration.jsp
<form:form method="post" modelAttribute="customer" action="doCustomerRegistration">
</form:form>
what if the jsp have two model object information like Customer and product information like customerName,customerAddress,customerPhoneNumber,productID,productName,productPrice here i like to have two model object like customer
& Product if i have two model object how can i map model attribute from jsp and Spring contoller and how can i do server side validation for both the validation

Answer 1

Although it is a good idea to keep models separate in each form, but for this particular use case it can be achieved by following below steps.
The best way to achieve this is to wrap both the Model attributes in one wrapper class and use it in validation.
Lets say Product class looks like this.
public class Product{
String productName;
// other fields and their getter setters
}
Create a wrapper class which wraps both models Customer and Product
public class CustomerProductWrapper {
private Customer customer;
private Product product;
//getter setter
}
In your validator class , change the implementation of supports() method as below
#Override
public boolean supports(Class clazz) {
return CustomerProductWrapper .class.equals(clazz);
}
2.1 Change the implementation of Validation Method as below
#Override
public void validate(Object obj, Errors err) {
//The object that you get now is CustomerProductWrapper object
// refer the fields using this object
ValidationUtils.rejectIfEmpty(err, "customer.name", "customer.name.empty");
ValidationUtils.rejectIfEmpty(err, "customer.email", "customer.email.empty");
ValidationUtils.rejectIfEmpty(err, "customer.gender", "customer.gender.empty");
ValidationUtils.rejectIfEmpty(err, "customer.languages", "customer.languages.empty");
CustomerProductWrapper cpw= (CustomerProductWrapper ) obj;
Pattern pattern = Pattern.compile("^[A-Z0-9._%+-]+#[A-Z0-9.-]+\\.[A-Z]{2,6}$",
Pattern.CASE_INSENSITIVE);
if (!(pattern.matcher(cpw.getCustomer().getEmail()).matches())) {
err.rejectValue("customer.email", "user.email.invalid");
}
//validate a Product field
ValidationUtils.rejectIfEmpty(err, "product.productName", "product.name.empty");
}
In your controller mapping ,
public String customerRegistrationScreen(Model model) {
CustomerProductWrapper cpw= new CustomerProductWrapper ();
model.addAttribute("cpw", cpw);
return "customerRegistrationScreen";
}
And
#RequestMapping(value = "/doCustomerRegistration", method = RequestMethod.POST)
public ModelAndView registerCustomer(#ModelAttribute("cpw") #Validated CustomerProductWrapper cpw, BindingResult result,Model model) {
if (result.hasErrors()) {
} else {
}
}
And finally in your view page
<form:form method="post" modelAttribute="cpw" action="doCustomerRegistration">
</form:form>
Also refer fields using cpw's attributes that is
<form:input path="name" />
<form:errors path="name" cssClass="error" />
will change to
<form:input path="customer.name" />
<form:errors path="customer.name" cssClass="error" />
Similarly for product validation you can use
<form:input path="product.productName" />
<form:errors path="product.productName" cssClass="error" />
That's all.