FormObjectAccessor.java
/*
* Copyright 2004-2012 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.webflow.action;
import org.springframework.validation.BindingResult;
import org.springframework.validation.Errors;
import org.springframework.webflow.execution.RequestContext;
import org.springframework.webflow.execution.ScopeType;
/**
* Convenience helper that encapsulates logic on how to retrieve and expose form objects and associated errors to and
* from a flow execution request context.
* <p>
* <b>Note</b>: The form object available under the well known attribute name will be the last ("current") form object
* set in the request context. The same is true for the associated errors object. This implies that special care should
* be taken when accessing the form object using this alias if there are multiple form objects available in the flow
* execution request context!
*
* @see org.springframework.webflow.execution.RequestContext
* @see org.springframework.validation.Errors
*
* @author Keith Donald
* @author Erwin Vervaet
*/
public class FormObjectAccessor {
/**
* The form object instance is aliased under this attribute name in the flow context by the default form setup and
* bind and validate actions.
* <p>
* Note that if you would have multiple form objects in the request context, the last one that was used would be
* available using this alias!
* <p>
* We need to keep track of the 'current form object' using this attribute to be able to deal with the limitations
* of some clients that can only deal with a single form backing object, e.g. Struts when using the Struts
* FlowAction.
*/
private static final String CURRENT_FORM_OBJECT_ATTRIBUTE = "currentFormObject";
/**
* The errors prefix.
*/
private static final String ERRORS_PREFIX = BindingResult.MODEL_KEY_PREFIX;
/**
* The wrapped request context.
*/
private RequestContext context;
/**
* Creates a form object accessor that wraps the given context.
* @param context the flow execution request context
*/
public FormObjectAccessor(RequestContext context) {
this.context = context;
}
/**
* Returns the current form object name.
* @return the current form object name
*/
public static String getCurrentFormObjectName() {
return CURRENT_FORM_OBJECT_ATTRIBUTE;
}
/**
* Returns the current form object errors attribute name.
* @return the current form object errors attribute name
*/
public static String getCurrentFormErrorsName() {
return ERRORS_PREFIX + getCurrentFormObjectName();
}
/**
* Gets the form object from the context, using the well-known attribute name. Will try all scopes.
* @return the form object, or null if not found
*/
public Object getCurrentFormObject() {
Object formObject = getCurrentFormObject(ScopeType.REQUEST);
if (formObject != null) {
return formObject;
}
formObject = getCurrentFormObject(ScopeType.FLASH);
if (formObject != null) {
return formObject;
}
formObject = getCurrentFormObject(ScopeType.FLOW);
if (formObject != null) {
return formObject;
}
return getCurrentFormObject(ScopeType.CONVERSATION);
}
/**
* Gets the form object from the context, using the well-known attribute name.
* @param scopeType the scope to obtain the form object from
* @return the form object, or null if not found
*/
public Object getCurrentFormObject(ScopeType scopeType) {
return getFormObject(getCurrentFormObjectName(), scopeType);
}
/**
* Expose given form object using the well known alias in the specified scope.
* @param formObject the form object
* @param scopeType the scope in which to expose the form object
*/
public void setCurrentFormObject(Object formObject, ScopeType scopeType) {
// don't call setFormObject since that would cause infinite recursion!
scopeType.getScope(context).put(getCurrentFormObjectName(), formObject);
}
/**
* Gets the form object from the context, using the specified name.
* @param formObjectName the name of the form object in the context
* @param scopeType the scope to obtain the form object from
* @return the form object, or null if not found
*/
public Object getFormObject(String formObjectName, ScopeType scopeType) {
return scopeType.getScope(context).get(formObjectName);
}
/**
* Gets the form object from the context, using the specified name.
* @param formObjectName the name of the form in the context
* @param formObjectClass the class of the form object, which will be verified
* @param scopeType the scope to obtain the form object from
* @return the form object, or null if not found
*/
public Object getFormObject(String formObjectName, Class<?> formObjectClass, ScopeType scopeType) {
return scopeType.getScope(context).get(formObjectName, formObjectClass);
}
/**
* Expose given form object using given name in specified scope. Given object will become the <i>current</i> form
* object.
* @param formObject the form object
* @param formObjectName the name of the form object
* @param scopeType the scope in which to expose the form object
*/
public void putFormObject(Object formObject, String formObjectName, ScopeType scopeType) {
scopeType.getScope(context).put(formObjectName, formObject);
setCurrentFormObject(formObject, scopeType);
}
/**
* Gets the form object <code>Errors</code> tracker from the context, using the form object name. This method will
* search all scopes.
* @return the form object Errors tracker, or null if not found
*/
public Errors getCurrentFormErrors() {
Errors errors = getCurrentFormErrors(ScopeType.REQUEST);
if (errors != null) {
return errors;
}
errors = getCurrentFormErrors(ScopeType.FLASH);
if (errors != null) {
return errors;
}
errors = getCurrentFormErrors(ScopeType.FLOW);
if (errors != null) {
return errors;
}
return getCurrentFormErrors(ScopeType.CONVERSATION);
}
/**
* Gets the form object <code>Errors</code> tracker from the context, using the form object name.
* @param scopeType the scope to obtain the errors from
* @return the form object Errors tracker, or null if not found
*/
public Errors getCurrentFormErrors(ScopeType scopeType) {
return getFormErrors(getCurrentFormObjectName(), scopeType);
}
/**
* Expose given errors instance using the well known alias in the specified scope.
* @param errors the errors instance
* @param scopeType the scope in which to expose the errors instance
*/
public void setCurrentFormErrors(Errors errors, ScopeType scopeType) {
scopeType.getScope(context).put(getCurrentFormErrorsName(), errors);
}
/**
* Gets the form object <code>Errors</code> tracker from the context, using the specified form object name.
* @param formObjectName the name of the Errors object, which will be prefixed with
* {@link BindingResult#MODEL_KEY_PREFIX}
* @param scopeType the scope to obtain the errors from
* @return the form object errors instance, or null if not found
*/
public Errors getFormErrors(String formObjectName, ScopeType scopeType) {
return scopeType.getScope(context).get(ERRORS_PREFIX + formObjectName, Errors.class);
}
/**
* Expose given errors instance in the specified scope. Given errors instance will become the <i>current</i> form
* errors instance.
* @param errors the errors object
* @param scopeType the scope to expose the errors in
*/
public void putFormErrors(Errors errors, ScopeType scopeType) {
scopeType.getScope(context).put(ERRORS_PREFIX + errors.getObjectName(), errors);
setCurrentFormErrors(errors, scopeType);
}
}