tag 'select', field 'list', name 'uuid': The requested list key 'deptList' could not be resolved as a collection/array/map/enumeration/iterator type

Question

I have a struts2 problem, it only happens when there is a validation error (it doesn't happen when I load my page for the first time and doesn't happen if the validation error doesn't occur) If I remove select tags, it works fine, and it shows the validation error messages after I submit the form, but I need those selects, and they have dynamic information from the DB, so they need to be preloaded each time my form is displayed. I tried to put the deptList and roleList in valuestack or put them to session, same thing happened.

This is the part of the Action Class code:

private List<DeptModel> deptList;
private List<RoleModel> roleList;
public List<RoleModel> getRoleList() {
    return roleList;
}
public void setRoleList(List<RoleModel> roleList) {
    this.roleList = roleList;
}

public List<DeptModel> getDeptList() {
    return deptList;
}

public void setDeptList(List<DeptModel> deptList) {
    this.deptList = deptList;
}
public String input() {
    roleList = roleEbi.getAll();
    this.setRoleList(roleList);
    deptList = deptEbi.getAll();
    this.setDeptList(deptList);
    if (empModel.getUuid() != null) {// for data display when doing modify
        empModel = empEbi.get(empModel.getUuid());
        roleUuids = new Long[empModel.getRoles().size()];
        int i = 0;
        for (RoleModel temp : empModel.getRoles()) {
            roleUuids[i++] = temp.getUuid();
        }
    }
    return INPUT;
}

public String save(){
    if(empModel.getUuid() == null ){
        empEbi.save(empModel,roleUuids);
    }else{
        empEbi.update(empModel,roleUuids);
    }
    return TO_LIST;
}

This is the JSP page:

<s:form action="emp_save" method="post" onsubmit="return checkForm();">
  <s:textfield id="username" name="empModel.userName" />
  <s:textfield id="password" size="25" name="empModel.pwd"/>
  <s:select name="empModel.deptModel.uuid" list="deptList" style="width:190px" listKey="uuid" listValue="name" />
  <s:checkboxlist name="roleUuids" list="roleList" listKey="uuid" listValue="name"/>
  <a href="javascript:document.forms[0].submit()"><img src="images/save.jpg" border="0" width="81px"/></a>
</s:form>

This is the error from the struts report:

tag 'select', field 'list', name 'empModel.deptModel.uuid': The requested list key 'deptList' could not be resolved as a collection/array/map/enumeration/iterator type. Example: people or people.{name}

This is my validation xml:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE validators PUBLIC
    "-//Apache Struts//XWork Validator 1.0.3//EN"
    "http://struts.apache.org/dtds/xwork-validator-1.0.3.dtd">
    <validators>
        <field name="empModel.userName">
            <field-validator type="requiredstring">
                <param name="trim">true</param>
                <message>User Name can not be null ~~~</message>
            </field-validator>
        </field>
        <field name="empModel.pwd">
            <field-validator type="requiredstring">
                <message>Password can not be null ~~~</message>
            </field-validator>
        </field>
    </validators>

Answer 1

When you submit form the validation errors prevent the action execution, because the workflow interceptor returns result INPUT. You can configure this interceptor via adding annotation on the action method

@InputConfig(methodName="input")
public String save(){
    if(empModel.getUuid() == null ){
        empEbi.save(empModel,roleUuids);
    }else{
        empEbi.update(empModel,roleUuids);
    }
    return TO_LIST;
}

It will call method input from the interceptor to initialize lists before returning INPUT result by this method.