What about those instances when a client application has a document that needs to set values based on user input but which do not require any further user prompts before the document is validated? This is where org.kuali.rice.kns.web.derviedvaluesetter.DerivedValuesSetter steps in.

DerivedValuesSetter has one method:

public void setDerivedValues(KualiForm form, HttpServletRequest request);

Nothing is returned, and the arguments are basically the web form and the servlet request itself. Values can be gathered from either of those sources, and then values can be set anywhere on the form – though it would typically be expected that the document in the KualiForm would be where everything is set.

Actual examples of DerivedValuesSetter implementations is fairly rare. There is one example from KFS 3.0 which will be used as an example, associated with the Organization Maintenance Document. First, the DerivedValuesSetter is set in the data dictionary for the document:

<bean id="OrganizationMaintenanceDocument" parent="MaintenanceDocumentEntry">
    <property name="businessObjectClass" value="org.kuali.kfs.coa.businessobject.Organization"/>
    <property name="documentTypeName" value="ORGN"/>
    <property name="promptBeforeValidationClass" value="org.kuali.kfs.coa.document.validation.impl.OrgPreRules"/>
    <property name="derivedValuesSetterClass" value="org.kuali.kfs.coa.document.web.OrgDerivedValuesSetter"/>
        ...
</bean>

The actual DerivedValuesSetter itself attempts to use the PostalCodeService to set the city and state of the organization. Here’s a simplified version:

public class OrgDerivedValuesSetter implements DerivedValuesSetter {
    public void setDerivedValues(KualiForm form, HttpServletRequest request) {
        final Organization newOrg = (Organization) ((MaintenanceDocumentBase)((KualiMaintenanceForm) form).getDocument()).getNewMaintainableObject().getBusinessObject();
        final String organizationZipCode = newOrg.getOrganizationZipCode();
        final String organizationCountryCode = newOrg.getOrganizationCountryCode();
        if (StringUtils.isNotBlank(organizationZipCode) && StringUtils.isNotBlank(organizationCountryCode)) {
            final PostalCode postalZipCode = SpringContext.getBean(PostalCodeService.class).getByPrimaryId(organizationCountryCode, organizationZipCode);
            if (ObjectUtils.isNotNull(postalZipCode)) {
                newOrg.setOrganizationCityName(postalZipCode.getPostalCityName());
                newOrg.setOrganizationStateCode(postalZipCode.getPostalStateCode());
            }
        }
    }

}

Here, the new Organization business object is pulled from the maintenance document, and from that, the zip code and country code are pulled. The code attempts to use the country and zip codes to find a postal code, and if one is found, it sets the city and state of the document.

Both PromptBeforeValidation and DerivedValuesSetter classes offer KNS client application developers the flexibility to prompt the user or set values on a document before that document goes into validation.