Spring validation errors not displayed

java, spring, spring-mvc, validation

Solution

I found what is your problem. property `fields` in object `myCommand` always null. You need to create constructor for class MyCommand in which you need to use `LazyList` from Apache Commons or `AutoPopulatingList` from Spring to create auto growing list of `Field`

In example (using AutoPopulatingList):

public class MyCommand {   
    private List<Field> fields;   
    private int limit;   

    //getters and setters
    //...
    //Constructor
    public MyCommand() {
        fields = new AutoPopulatingList<Field>(Field.class);
    } 
}

Problem

I have the following situation. I have a validator to validate my command object and set the errors on a Errors object to be displayed in my form. The validator is invoked as expected and works okay, but the errors i set on the Errors objects are not displayed, when i am sent back to my form because of the validation errors. Validator: ``` public void validate(Object obj, Errors err) { MyCommand myCommand = (MyCommand) obj; int index = 0; for (Field field : myCommand.getFields()) { if (field.isChecked()) { if ((field.getValue() == null) || (field.getValue().equals(""))) { err.rejectValue("fields[" + index + "].value", "errors.missing"); } } index++; } if (myCommand.getLimit() < 0) { err.rejectValue("limit", "errors.invalid"); } } ``` Command: ``` public class MyCommand { private List<Field> fields; private int limit; //getters and setters } public class Field { private boolean checked; private String name; private String value; //getters and setters } ``` Form: ``` <form:form id="myForm" method="POST" action="${url}" commandName="myCommand"> <c:forEach items="${myCommand.fields}" var="field" varStatus="status"> <form:checkbox path="fields[${status.index}].checked" value="${field.checked}" /> <c:out value="${field.name}" /> <form:input path="fields[${status.index}].value" /> <form:errors path="fields[${status.index}].value" cssClass="error" /></td> <form:hidden path="fields[${status.index}].name" /> </c:forEach> <fmt:message key="label.limit" /> <form:input path="limit" /> <form:errors path="limit" cssClass="error" /> </form:form> ``` Controller: ``` @RequestMapping(value = REQ_MAPPING, method = RequestMethod.POST) public String onSubmit(Model model, MyCommand myCommand, BindingResult result) { // validate myCommandValidator.validate(myCommand, result); if (result.hasErrors()) { model.addAttribute("myCommand", myCommand); return VIEW; } // form is okay, do stuff and redirect } ``` Could it be that the paths i give in the validator and tag are not correct? The validator validates a command object containing a list of objects, so that's why i give a index on the list in the command object when registering an error message (for example: "fields["+index+"]".value). Or is it that the Errors object containing the errors is not available to my view? Any help is welcome and appreciated, it might give me a hint or point me in right direction.

Original source