/*
* Copyright 2002-2016 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
*
* http://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.web.servlet.tags.form;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.BodyTag;
import org.springframework.util.Assert;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;
/**
* Form tag for displaying errors for a particular field or object.
*
* <p>This tag supports three main usage patterns:
*
* <ol>
* <li>Field only - set '{@code path}' to the field name (or path)</li>
* <li>Object errors only - omit '{@code path}'</li>
* <li>All errors - set '{@code path}' to '{@code *}'</li>
* </ol>
*
* @author Rob Harrop
* @author Juergen Hoeller
* @author Rick Evans
* @since 2.0
*/
@SuppressWarnings("serial")
public class ErrorsTag extends AbstractHtmlElementBodyTag implements BodyTag {
/**
* The key under which this tag exposes error messages in
* the {@link PageContext#PAGE_SCOPE page context scope}.
*/
public static final String MESSAGES_ATTRIBUTE = "messages";
/**
* The HTML '{@code span}' tag.
*/
public static final String SPAN_TAG = "span";
private String element = SPAN_TAG;
private String delimiter = "<br/>";
/**
* Stores any value that existed in the 'errors messages' before the tag was started.
*/
private Object oldMessages;
private boolean errorMessagesWereExposed;
/**
* Set the HTML element must be used to render the error messages.
* <p>Defaults to an HTML '{@code <span/>}' tag.
*/
public void setElement(String element) {
Assert.hasText(element, "'element' cannot be null or blank");
this.element = element;
}
/**
* Get the HTML element must be used to render the error messages.
*/
public String getElement() {
return this.element;
}
/**
* Set the delimiter to be used between error messages.
* <p>Defaults to an HTML '{@code <br/>}' tag.
*/
public void setDelimiter(String delimiter) {
this.delimiter = delimiter;
}
/**
* Return the delimiter to be used between error messages.
*/
public String getDelimiter() {
return this.delimiter;
}
/**
* Get the value for the HTML '{@code id}' attribute.
* <p>Appends '{@code .errors}' to the value returned by {@link #getPropertyPath()}
* or to the model attribute name if the {@code <form:errors/>} tag's
* '{@code path}' attribute has been omitted.
* @return the value for the HTML '{@code id}' attribute
* @see #getPropertyPath()
*/
@Override
protected String autogenerateId() throws JspException {
String path = getPropertyPath();
if ("".equals(path) || "*".equals(path)) {
path = (String) this.pageContext.getAttribute(
FormTag.MODEL_ATTRIBUTE_VARIABLE_NAME, PageContext.REQUEST_SCOPE);
}
return StringUtils.deleteAny(path, "[]") + ".errors";
}
/**
* Get the value for the HTML '{@code name}' attribute.
* <p>Simply returns {@code null} because the '{@code name}' attribute
* is not a validate attribute for the '{@code span}' element.
*/
@Override
protected String getName() throws JspException {
return null;
}
/**
* Should rendering of this tag proceed at all?
* <p>Only renders output when there are errors for the configured {@link #setPath path}.
* @return {@code true} only when there are errors for the configured {@link #setPath path}
*/
@Override
protected boolean shouldRender() throws JspException {
try {
return getBindStatus().isError();
}
catch (IllegalStateException ex) {
// Neither BindingResult nor target object available.
return false;
}
}
@Override
protected void renderDefaultContent(TagWriter tagWriter) throws JspException {
tagWriter.startTag(getElement());
writeDefaultAttributes(tagWriter);
String delimiter = ObjectUtils.getDisplayString(evaluate("delimiter", getDelimiter()));
String[] errorMessages = getBindStatus().getErrorMessages();
for (int i = 0; i < errorMessages.length; i++) {
String errorMessage = errorMessages[i];
if (i > 0) {
tagWriter.appendValue(delimiter);
}
tagWriter.appendValue(getDisplayString(errorMessage));
}
tagWriter.endTag();
}
/**
* Exposes any bind status error messages under {@link #MESSAGES_ATTRIBUTE this key}
* in the {@link PageContext#PAGE_SCOPE}.
* <p>Only called if {@link #shouldRender()} returns {@code true}.
* @see #removeAttributes()
*/
@Override
protected void exposeAttributes() throws JspException {
List<String> errorMessages = new ArrayList<>();
errorMessages.addAll(Arrays.asList(getBindStatus().getErrorMessages()));
this.oldMessages = this.pageContext.getAttribute(MESSAGES_ATTRIBUTE, PageContext.PAGE_SCOPE);
this.pageContext.setAttribute(MESSAGES_ATTRIBUTE, errorMessages, PageContext.PAGE_SCOPE);
this.errorMessagesWereExposed = true;
}
/**
* Removes any bind status error messages that were previously stored under
* {@link #MESSAGES_ATTRIBUTE this key} in the {@link PageContext#PAGE_SCOPE}.
* @see #exposeAttributes()
*/
@Override
protected void removeAttributes() {
if (this.errorMessagesWereExposed) {
if (this.oldMessages != null) {
this.pageContext.setAttribute(MESSAGES_ATTRIBUTE, this.oldMessages, PageContext.PAGE_SCOPE);
this.oldMessages = null;
}
else {
this.pageContext.removeAttribute(MESSAGES_ATTRIBUTE, PageContext.PAGE_SCOPE);
}
}
}
}