SPR-5267 Support for PUT and DELETE in spring:form tag

Any HTTP method passed to the spring-form:form tag other then GET or POST will automatically be defaulted to POST on the form tag and a hidden input field is created with the requested HTTP method.  By default, the hidden field is named '_method', the name can be overridden using the methodParam attribute on the spring-form:form tag.

org.springframework.web.servlet/src/main/java/org/springframework/web/servlet/tags/form/FormTag.java

@@ -43,6 +43,7 @@ import org.springframework.web.util.HtmlUtils;
  *
  * @author Rob Harrop
  * @author Juergen Hoeller
+ * @author Scott Andrews
  * @since 2.0
  * @see org.springframework.web.servlet.mvc.SimpleFormController
  */
@@ -64,6 +65,12 @@ public class FormTag extends AbstractHtmlElementTag {
 	public static final String MODEL_ATTRIBUTE_VARIABLE_NAME =
 			Conventions.getQualifiedAttributeName(AbstractFormTag.class, MODEL_ATTRIBUTE);
 
+	/** Default method parameter, i.e. <code>_method</code>. */
+	private static final String DEFAULT_METHOD_PARAM = "_method";
+
+	private static final String FORM_TAG = "form";
+
+	private static final String INPUT_TAG = "input";
 
 	private static final String ACTION_ATTRIBUTE = "action";
 
@@ -81,6 +88,12 @@ public class FormTag extends AbstractHtmlElementTag {
 
 	private static final String AUTOCOMPLETE_ATTRIBUTE = "autocomplete";
 
+	private static final String NAME_ATTRIBUTE = "name";
+
+	private static final String VALUE_ATTRIBUTE = "value";
+
+	private static final String TYPE_ATTRIBUTE = "type";
+
 
 	private TagWriter tagWriter;
 
@@ -104,6 +117,8 @@ public class FormTag extends AbstractHtmlElementTag {
 
 	private String autocomplete;
 
+	private String methodParam = DEFAULT_METHOD_PARAM;
+
 	/** Caching a previous nested path, so that it may be reset */
 	private String previousNestedPath;
 
@@ -278,6 +293,27 @@ public class FormTag extends AbstractHtmlElementTag {
 		return this.autocomplete;
 	}
 
+	/**
+	 * Set the name of the request param for non-browser supported HTTP methods
+	 */
+	public void setMethodParam(String methodParam) {
+		this.methodParam = methodParam;
+	}
+
+	/**
+	 * Get the name of the request param for non-browser supported HTTP methods
+	 */
+	protected String getMethodParameter() {
+		return this.methodParam;
+	}
+
+	/**
+	 * Determine if the HTTP method is browser supported
+	 */
+	protected boolean isMethodBrowserSupported(String method) {
+		return ("get".equalsIgnoreCase(method) || "post".equalsIgnoreCase(method));
+	}
+
 
 
 	/**
@@ -290,10 +326,10 @@ public class FormTag extends AbstractHtmlElementTag {
 	protected int writeTagContent(TagWriter tagWriter) throws JspException {
 		this.tagWriter = tagWriter;
 
-		tagWriter.startTag("form");
+		tagWriter.startTag(FORM_TAG);
 		writeDefaultAttributes(tagWriter);
 		tagWriter.writeAttribute(ACTION_ATTRIBUTE, resolveAction());
-		writeOptionalAttribute(tagWriter, METHOD_ATTRIBUTE, getMethod());
+		writeOptionalAttribute(tagWriter, METHOD_ATTRIBUTE, isMethodBrowserSupported(getMethod()) ? getMethod() : DEFAULT_METHOD);
 		writeOptionalAttribute(tagWriter, TARGET_ATTRIBUTE, getTarget());
 		writeOptionalAttribute(tagWriter, ENCTYPE_ATTRIBUTE, getEnctype());
 		writeOptionalAttribute(tagWriter, ACCEPT_CHARSET_ATTRIBUTE, getAcceptCharset());
@@ -303,6 +339,14 @@ public class FormTag extends AbstractHtmlElementTag {
 
 		tagWriter.forceBlock();
 
+		if (!isMethodBrowserSupported(getMethod())) {
+			tagWriter.startTag(INPUT_TAG);
+			writeOptionalAttribute(tagWriter, TYPE_ATTRIBUTE, "hidden");
+			writeOptionalAttribute(tagWriter, NAME_ATTRIBUTE, getMethodParameter());
+			writeOptionalAttribute(tagWriter, VALUE_ATTRIBUTE, getMethod());
+			tagWriter.endTag();
+		}
+
 		// Expose the form object name for nested tags...
 		String modelAttribute = resolveModelAttribute();
 		this.pageContext.setAttribute(MODEL_ATTRIBUTE_VARIABLE_NAME, modelAttribute, PageContext.REQUEST_SCOPE);

org.springframework.web.servlet/src/main/java/org/springframework/web/servlet/tags/form/spring-form.tld

@@ -186,6 +186,12 @@
 			<rtexprvalue>true</rtexprvalue>
 			<description>Common Optional Attribute</description>
 		</attribute>
+		<attribute>
+			<name>methodParam</name>
+			<required>false</required>
+			<rtexprvalue>true</rtexprvalue>
+			<description>The parameter name used for HTTP methods other then GET and POST. Default is '_method'</description>
+		</attribute>
 	</tag>
 
 	<!-- <form:input/> tag -->

org.springframework.web.servlet/src/test/java/org/springframework/web/servlet/tags/form/FormTagTests.java

@@ -25,6 +25,7 @@ import org.springframework.mock.web.MockHttpServletRequest;
  * @author Rob Harrop
  * @author Rick Evans
  * @author Juergen Hoeller
+ * @author Scott Andrews
  */
 public class FormTagTests extends AbstractHtmlElementTagTests {
 	
@@ -170,6 +171,100 @@ public class FormTagTests extends AbstractHtmlElementTagTests {
 				getOutput());
 	}
 	
+	public void testGet() throws Exception {
+		this.tag.setMethod("get");
+		
+		this.tag.doStartTag();
+		this.tag.doEndTag();
+		this.tag.doFinally();
+		
+		String output = getOutput();
+		String formOutput = getFormTag(output);
+		String inputOutput = getInputTag(output);
+		
+		assertContainsAttribute(formOutput, "method", "get");
+		assertEquals("", inputOutput);
+	}
+	
+	public void testPost() throws Exception {
+		this.tag.setMethod("post");
+		
+		this.tag.doStartTag();
+		this.tag.doEndTag();
+		this.tag.doFinally();
+
+		String output = getOutput();
+		String formOutput = getFormTag(output);
+		String inputOutput = getInputTag(output);
+		
+		assertContainsAttribute(formOutput, "method", "post");
+		assertEquals("", inputOutput);
+	}
+	
+	public void testPut() throws Exception {
+		this.tag.setMethod("put");
+		
+		this.tag.doStartTag();
+		this.tag.doEndTag();
+		this.tag.doFinally();
+
+		String output = getOutput();
+		String formOutput = getFormTag(output);
+		String inputOutput = getInputTag(output);
+
+		assertContainsAttribute(formOutput, "method", "post");
+		assertContainsAttribute(inputOutput, "name", "_method");
+		assertContainsAttribute(inputOutput, "value", "put");
+		assertContainsAttribute(inputOutput, "type", "hidden");
+	}
+	
+	public void testDelete() throws Exception {
+		this.tag.setMethod("delete");
+		
+		this.tag.doStartTag();
+		this.tag.doEndTag();
+		this.tag.doFinally();
+
+		String output = getOutput();
+		String formOutput = getFormTag(output);
+		String inputOutput = getInputTag(output);
+
+		assertContainsAttribute(formOutput, "method", "post");
+		assertContainsAttribute(inputOutput, "name", "_method");
+		assertContainsAttribute(inputOutput, "value", "delete");
+		assertContainsAttribute(inputOutput, "type", "hidden");
+	}
+	
+	public void testCustomMethodParameter() throws Exception {
+		this.tag.setMethod("put");
+		this.tag.setMethodParam("methodParameter");
+		
+		this.tag.doStartTag();
+		this.tag.doEndTag();
+		this.tag.doFinally();
+
+		String output = getOutput();
+		String formOutput = getFormTag(output);
+		String inputOutput = getInputTag(output);
+
+		assertContainsAttribute(formOutput, "method", "post");
+		assertContainsAttribute(inputOutput, "name", "methodParameter");
+		assertContainsAttribute(inputOutput, "value", "put");
+		assertContainsAttribute(inputOutput, "type", "hidden");
+	}
+
+	private String getFormTag(String output) {
+		int inputStart = output.indexOf("<", 1);
+		int inputEnd = output.lastIndexOf(">", output.length() - 2);
+		return output.substring(0, inputStart) + output.substring(inputEnd + 1);
+	}
+
+	private String getInputTag(String output) {
+		int inputStart = output.indexOf("<", 1);
+		int inputEnd = output.lastIndexOf(">", output.length() - 2);
+		return output.substring(inputStart, inputEnd + 1);
+	}
+
 
 	private static void assertFormTagOpened(String output) {
 		assertTrue(output.startsWith("<form "));