package org.springmodules.validation.bean.conf.loader.xml.handler;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;
import org.springmodules.validation.bean.conf.MutableBeanValidationConfiguration;
import org.springmodules.validation.bean.rule.AbstractValidationRule;
import org.springmodules.validation.bean.rule.resolver.ErrorArgumentsResolver;
import org.springmodules.validation.bean.rule.resolver.FunctionErrorArgumentsResolver;
import org.springmodules.validation.util.cel.ConditionExpressionBased;
import org.springmodules.validation.util.cel.ConditionExpressionParser;
import org.springmodules.validation.util.cel.valang.ValangConditionExpressionParser;
import org.springmodules.validation.util.condition.Condition;
import org.springmodules.validation.util.fel.FunctionExpressionBased;
import org.springmodules.validation.util.fel.FunctionExpressionParser;
import org.springmodules.validation.util.fel.parser.ValangFunctionExpressionParser;
import org.w3c.dom.Element;
/**
* A base class for common {@link PropertyValidationElementHandler}
* implementations that represent validation rules. This base handler idetifies the supported elements by their
* tag names (qualified and local). In addition, it assumes the following common attributes:
* <p/>
* <ul>
* <li>code - Indicates the error code of the validatoin rule</li>
* <li>message - The default error message of the validation rule</li>
* <li>args - A comma separated list of error arguments</li>
* <li>apply-if - An condition expression that determines the applicability of the validation rule</li>
* </ul>
* <p/>
* Note: The apply-if attribute is being parsed by the
* {@link org.springmodules.validation.util.cel.ConditionExpressionParser} that is associated with this handler. It
* uses {@link org.springmodules.validation.util.cel.valang.ValangConditionExpressionParser} by default.
*
* @author Uri Boness
*/
public abstract class AbstractClassValidationElementHandler
implements ClassValidationElementHandler, ConditionExpressionBased, FunctionExpressionBased {
private static final String ERROR_CODE_ATTR = "code";
private static final String MESSAGE_ATTR = "message";
private static final String ARGS_ATTR = "args";
private static final String APPLY_IF_ATTR = "apply-if";
private static final String CONTEXTS_ATTR = "contexts";
private String elementName;
private String namespaceUrl;
private ConditionExpressionParser conditionExpressionParser;
private FunctionExpressionParser functionExpressionParser;
/**
* Constructs a new AbstractPropertyValidationElementHandler with given supported element name.
*
* @param elementName The supported element name.
*/
public AbstractClassValidationElementHandler(String elementName) {
this(elementName, null);
}
/**
* Constructs a new AbstractPropertyValidationElementHandler with given supported element name and namespace.
*
* @param elementName The supported element name.
* @param namespace The supported namespace.
*/
public AbstractClassValidationElementHandler(String elementName, String namespace) {
this(elementName, namespace, new ValangConditionExpressionParser(), new ValangFunctionExpressionParser());
}
/**
* Constructs a new AbstractPropertyValidationElementHandler with given supported element name and namespace and a
* condition handler to parse the <code>apply-if</code> expressions.
*
* @param elementName The supported element name.
* @param namespace The supported namespace.
* @param conditionExpressionParser The condition expression parser to be used to parse the various condition expressions.
* @param functionExpressionParser The function expression parser to be used to parse the error arguments expressions.
*/
public AbstractClassValidationElementHandler(
String elementName,
String namespace,
ConditionExpressionParser conditionExpressionParser,
FunctionExpressionParser functionExpressionParser) {
this.elementName = elementName;
this.namespaceUrl = namespace;
this.conditionExpressionParser = conditionExpressionParser;
this.functionExpressionParser = functionExpressionParser;
}
/**
* Determines whether the given element is supported by this handler. The check is done by comparing the element
* tag name and namespace with the ones that are configured with this handler.
*
* @see org.springmodules.validation.bean.conf.loader.xml.handler.PropertyValidationElementHandler#supports(org.w3c.dom.Element, Class, java.beans.PropertyDescriptor)
*/
public boolean supports(Element element, Class clazz) {
String localName = element.getLocalName();
if (!localName.equals(elementName)) {
return false;
}
String ns = element.getNamespaceURI();
return ObjectUtils.nullSafeEquals(ns, namespaceUrl);
}
/**
* Creates the appropriate {@link org.springmodules.validation.bean.rule.ValidationRule} based on the given element
* and adds it to the given configuration.
*
* @see org.springmodules.validation.bean.conf.loader.xml.handler.AbstractClassValidationElementHandler#handle(org.w3c.dom.Element, org.springmodules.validation.bean.conf.MutableBeanValidationConfiguration)
*/
public void handle(Element element, MutableBeanValidationConfiguration configuration) {
AbstractValidationRule rule = createValidationRule(element);
String errorCode = extractErrorCode(element);
if (errorCode != null) {
rule.setErrorCode(errorCode);
}
String message = extractMessage(element);
if (message != null) {
rule.setDefaultErrorMessage(message);
}
ErrorArgumentsResolver argumentsResolver = extractArgumentsResolver(element);
if (argumentsResolver != null) {
rule.setErrorArgumentsResolver(argumentsResolver);
}
Condition applicabilityCondition = extractApplicabilityCondition(element);
if (applicabilityCondition != null) {
rule.setApplicabilityCondition(applicabilityCondition);
}
String[] applicableContexts = extractApplicableContexts(element);
if (applicableContexts != null) {
rule.setContextTokens(applicableContexts);
}
configuration.addGlobalRule(rule);
}
/**
* By default the element handlers handle and produce rules that can be associated with both global and non-global
* contexts.
*/
public boolean isConditionGloballyScoped() {
return false;
}
/**
* Extracts the validation rule error code from the given element. Expects a "code" attribute to indicate the
* error code. If no such attribute exisits, returns <code>null</code>.
*
* @param element The element that represents the validation rule.
* @return The validation rule error code.
*/
protected String extractErrorCode(Element element) {
String code = element.getAttribute(AbstractClassValidationElementHandler.ERROR_CODE_ATTR);
return (StringUtils.hasLength(code)) ? code : null;
}
/**
* Extracts the validation rule error message from the given element. Expects a "message" attribute to indicate the
* error message. If no such attribute exisits, returns <code>null</code> instead.
*
* @param element The element that represents the validation rule.
* @return The validation rule error message.
*/
protected String extractMessage(Element element) {
String message = element.getAttribute(AbstractClassValidationElementHandler.MESSAGE_ATTR);
return (StringUtils.hasLength(message)) ? message : null;
}
/**
* Extracts the validation rule error arguments from the given element. Expects an "args" attribute to indicate the
* error arguments. If no such attribute exisits, returns <code>null</code>.
*
* @param element The element that represents the validation rule.
* @return The validation rule error arguments.
*/
protected ErrorArgumentsResolver extractArgumentsResolver(Element element) {
String argsString = element.getAttribute(AbstractClassValidationElementHandler.ARGS_ATTR);
String[] expressions = (argsString == null) ? new String[0] : StringUtils.tokenizeToStringArray(argsString, ", ");
if (expressions.length == 0) {
return null;
}
return new FunctionErrorArgumentsResolver(expressions, functionExpressionParser);
}
/**
* Extracts the validation rule applicability condition from the given element. Expects an "apply-if" attribute to
* indicate the condition expression. If no such attribute exisits, returns <code>null</code>.
*
* @param element The element that represents the validation rule.
* @return The validation rule applicability condition.
*/
protected Condition extractApplicabilityCondition(Element element) {
String expression = element.getAttribute(AbstractClassValidationElementHandler.APPLY_IF_ATTR);
return (StringUtils.hasText(expression)) ? conditionExpressionParser.parse(expression) : null;
}
/**
* Extracts the names of the validation context in which the valiation rule is applicable. Expects a "contexts"
* attribute to hold a comma-separated list of context names. If no such attribute exists or if it holds an empty
* string, <code>null </code> is returned. As the contract of {@link AbstractValidationRule#setContextTokens(String[])}
* defines <code>null</code> means that the rule always applies regardless of the context.
*
* @param element The element that represents the validation rule.
* @return The names of the validation contexts in which the
*/
protected String[] extractApplicableContexts(Element element) {
String contextString = element.getAttribute(CONTEXTS_ATTR);
return (StringUtils.hasText(contextString)) ? StringUtils.commaDelimitedListToStringArray(contextString) : null;
}
/**
* @see ConditionExpressionBased#setConditionExpressionParser(org.springmodules.validation.util.cel.ConditionExpressionParser)
*/
public void setConditionExpressionParser(ConditionExpressionParser conditionExpressionParser) {
this.conditionExpressionParser = conditionExpressionParser;
}
/**
* Returns the condition expression parser associated with this handler.
*
* @return The condition expression parser associated with this handler.
*/
protected ConditionExpressionParser getConditionExpressionParser() {
return conditionExpressionParser;
}
/**
* @see FunctionExpressionBased#setFunctionExpressionParser(org.springmodules.validation.util.fel.FunctionExpressionParser)
*/
public void setFunctionExpressionParser(FunctionExpressionParser functionExpressionParser) {
this.functionExpressionParser = functionExpressionParser;
}
/**
* Returns the {@link FunctionExpressionParser} used by this handler to parse the error argument expressions.
*
* @return The {@link FunctionExpressionParser} used by this handler to parse the error argument expressions.
*/
protected FunctionExpressionParser getFunctionExpressionParser() {
return functionExpressionParser;
}
/**
* Indicates whether the validation rule supports null values. Null values support means such values will be
* passed to the rule condition during validation. If the rule doesn't support null values, such value will not
* be evaluated by the rule condition and the validation will treat them as valid values.
*
* @return <code>true</code> if the validation rule support null values, <code>false</code> otherwise.
*/
protected boolean isNullSupported() {
return false;
}
/**
* Creates the validation rule represented and initialized by and with the given element.
*
* @param element The element that represents the validation rule.
* @return The newly created validation rule.
*/
protected abstract AbstractValidationRule createValidationRule(Element element);
}