Modified: struts/taglib/trunk/xdocs/faq.xml URL: http://svn.apache.org/viewcvs/struts/taglib/trunk/xdocs/faq.xml?rev=376854&r1=376853&r2=376854&view=diff ============================================================================== --- struts/taglib/trunk/xdocs/faq.xml (original) +++ struts/taglib/trunk/xdocs/faq.xml Fri Feb 10 13:09:57 2006 @@ -17,447 +17,632 @@ // ======================================================================== 78 --> <document> -<properties> -<title>Taglib FAQ</title> -</properties> -<body> -<a name="faq"/> -<section name="Struts Taglib FAQ"> - -<a name="contents"/> -<subsection name="Index"> - -<ul> - - <li> - <a href="#jsf">What about JSTL and JavaServer Faces?</a> - </li> - - <li> - <a href="#xhtml">Are the Struts tags XHTML compliant?</a> - </li> - - <li> - <a href="#wml">Will the Struts tags support other markup languages such as WML</a> - </li> - - <li> - <a href="#multiple">Can I use multiple HTML form elements with the same - name?</a> - </li> - - <li> - <a href="#multipleSubmits">Can I have multiple submit buttons on the same - form?</a> - </li> - - <li><a href="#focus">Why doesn't the focus feature on the <html:form> - tag work in every circumstance?</a> - </li> - - <li><a href="#checkbox">Why are my checkboxes not being set from ON to - OFF?</a> - </li> - - <li> - <a href="#javascript.submit">How do I use JavaScript to submit a form? </a> - </li> - - <li> - <a href="#javascript">How do I use JavaScript to ... </a> - </li> - - <li> - <a href="#reset">Do I need to implement reset and set all my form - properties to their initial values?</a> - </li> - - <li> - <a href="#scriptlets">Can't I just create some of my JavaBeans in the JSP - using a scriptlet?</a> - </li> - - <li> - <a href="#link">Why does the <html:link> tag URL-encode javascript and - mailto links?"</a> - </li> - - <li> - <a href="#pager">How can I scroll through list of pages like the search - results in google?</a> - </li> - - <li> - <a href="#minimization">Why does the option tag render selected="selected" - instead of just "selected"? - </a></li> - - <li> - <a href="#tags">Why does Struts Taglib provide for so little - formatting?</a> - </li> - - <li> - <a href="#layout">Why doesn't Struts Taglib offer more layout options?</a> - </li> - -</ul> - -</subsection> - -<a name="jsf"/> -<subsection name="What about JSTL and JavaServer Faces?"> - <p> - Struts Action Framework works well with the <a href="http://java.sun.com/products/jsp/jstl/";> - JavaServer Standard Tag Library</a>. - For a JSTL rendition of the original Struts JSP tags, - see the <a href="http://struts.apache.org/struts-el/index.html";>Struts EL subproject</a>. - </p> - - <p> - If you'd like to start using - <a href="http://java.sun.com/j2ee/javaserverfaces/";>JavaServer Faces</a> - components in your Struts Action Framework application, - please see the <a href="http://struts.apache.org/struts-faces/index.html";>Struts Faces</a> subproject. - If you'd like to get a fresh start in a pure JSF environment, - please see the <a href="http://struts.apache.org/shale/index.html";>Struts Shale</a> framework. - </p> -</subsection> - -<a name="xhtml"/> -<subsection name="Are the Struts tags XHTML compliant?"> -<p>If you use an <html:html xhtml="true> or <html:xhtml/> element on your page, the tags -will render as XHTML (since Struts 1.1). </p> -</subsection> - -<a name="wml"/> -<subsection name="Will the Struts tags support other markup languages such as WML"> -<p> -Struts itself is markup neutral. The original Struts taglibs are only one example of how -presentation layer components can access the framework. The framework objects are exposed -through the standard application, session, and request contexts, where any Java component in -the application can make use of them. -</p> - -<p>Markup extensions that use Struts are available for -<a href="http://jakarta.apache.org/velocity";>Velocity</a> and -<a href="http://www.openroad.ca/opencode/";>XLST</a>, among others. -A new Struts tag library for -<a href="#jsf">Java Server Faces</a> is also in development. -</p> - -<p>For more about using WAP/WML with Struts see the article -<a href="http://www.sys-con.com/pbdj/archives2/0904/hamboeck/";> -WAP up your EAserver</a>. -</p> -</subsection> - -<a name="multiple"/> -<subsection name="Can I use multiple HTML form elements with the same name?"> -<p> -Yes. Define the element as an array and Struts will autopopulate it like any other. -</p> -<pre> -<code> -private String[] id= {}; -public String[] getId() { return this.id; } -public void setItem(String id[]) {this.id = id;} -</code> -</pre> -<p> -And so forth -</p> -</subsection> - -<a name="multipleSubmits"/> -<subsection name="Can I have multiple submit buttons on the same form?"> -<p> -<strong>Yes</strong>. The issue is that only one action class can be -associated with a single form. So the real issue is how do I decode -multiple submit types to a single <code>Action</code> class. -There is more than one way to achieve this functionality.</p> -<p> -The way that is suggested by struts is right out of the javadoc for -<a href="../api/org/apache/struts/actions/LookupDispatchAction.html"> -<code>LookupDispatchAction</code></a>. -Basically, <code>LookupDispatchAction</code> is using the keys from -<code>ApplicationProperties.resources</code> as keys to a map of actions -available to your <code>Action</code> class. It uses -<a href="http://java.sun.com/j2se/1.3/docs/guide/reflection/";>reflection</a> to -decode the request and invoke the proper action. It also takes advantage of -the struts <a href="../userGuide/struts-html.html#submit"> -<code><html:submit></code></a> tags and is straight forward to implement.</p> -<p> -You can roll your own with JavaScript events and <code>javascript:void -(document.forms["myform"].submit)</code> on any html element. This gives you -control of how you want your page to look. Again you -will have to decode the expected action in the <code>execute</code> method of -your action form if you choose this route.</p> -</subsection> - -<a name="focus"/> -<subsection name="Why doesn't the focus feature on the <html:form> tag work in every circumstance?"> -<p> -Unfortunately, there is some disagreement between the various browsers, and different versions of the same browser, as to how the focus can be set. -The <html:form> tag provides a quick and easy JavaScript that will set the focus on a form -for most versions of most browsers. -If this feature doesn't work for you, then you should set the focus using your own JavaScript. -The focus feature is a convenient "value-add" -- not a core requirement of the tag. -If you do come up with a JavaScript that provides the final solution to this project, -please post your patch to this <a href="http://issues.apache.org/bugzilla/show_bug.cgi?id=13454";>Bugzilla ticket</a>. -</p> -</subsection> - -<a name="checkbox"/> -<subsection name="Why are my checkboxes not being set from ON to OFF?"> -<p> -A problem with a checkbox is that the browser will only include it in the request -when it is checked. If it is not checked, the HTML specification suggests that it -not be sent (i.e. omitted from the request). If the value of the checkbox is being -persisted, either in a session bean or in the model, a checked box can never -unchecked by a HTML form -- because the form can never send a signal to uncheck -the box. The application must somehow ascertain that since the element was not -sent that the corresponding value is unchecked. -</p> -<p> -The recommended approach for Struts applications is to use the reset method in the -ActionForm to set all properties represented by checkboxes to null or false. The -checked boxes submitted by the form will then set those properties to true. The -omitted properties will remain false. Another solution is to use radio buttons -instead, which always submit a value. -</p> -<p> -It is important to note that the HTML specification recommends this same -behavior whenever a control is not "successful". Any blank element in a HTML -form is not guaranteed to submitted. It is therefor very important to set the -default values for an ActionForm correctly, and to implement the reset method -when the ActionForm might kept in session scope. -</p> -</subsection> - -<a name="javascript.submit"/> -<subsection name="Can I use JavaScript to submit a form?"> -<p> - You can submit a form with a link as below. - BTW, the examples below assume you are in an <html:form> block and 'myForm' - is picked up from the struts-config.xml name field of the action. -</p> -<source> - <a href='javascript:void(document.forms["myForm"].submit()>My Link</a> -</source> -<p> - Now the trick in the action is to decode what action you intend to perform. - Since you are using JavaScript, you could set a field value and look for it in - the request or in the form. -</p> -<p> - ... html/javascript part ... -</p> -<source> - <input type='hidden' value='myAction' /> - <input type='button' value='Save Meeeee' - onclick='document.forms["myForm"].myAction.value="save"; - document.forms["myForm"].submit();' /> - <input type='button' value='Delete Meeeee' - onclick='document.forms["myForm"].myAction.value="delete"; - document.forms["myForm"].submit();' /> -</source> -<p> - ... the java part ... -</p> -<source> - class MyAction extends ActionForm implements Serializable { - - public ActionForward execute (ActionMapping map, ActionForm form, - HttpServletRequest req, HttpServletResponse) { + <properties> + <title>Taglib FAQ</title> + </properties> + <body> + <a name="faq"/> + <section name="Struts Taglib FAQ"> + + <a name="contents"/> + <subsection name="Index"> + + <ul> + + <li> + <a href="#jsf">What about JSTL and JavaServer + Faces?</a> + </li> + + <li> + <a href="#xhtml">Are the Struts tags XHTML + compliant?</a> + </li> + + <li> + <a href="#wml">Will the Struts tags support other + markup languages such as WML</a> + </li> + + <li> + <a href="#multiple">Can I use multiple HTML form + elements with the same + name?</a> + </li> + + <li> + <a href="#multipleSubmits">Can I have multiple submit + buttons on the same + form?</a> + </li> + + <li> + <a href="#focus">Why doesn't the focus feature on the + <html:form> + tag work in every circumstance?</a> + </li> + + <li> + <a href="#checkbox">Why are my checkboxes not being + set from ON to + OFF?</a> + </li> + + <li> + <a href="#javascript.submit">How do I use JavaScript + to submit a form?</a> + </li> + + <li> + <a href="#javascript">How do I use JavaScript to + ...</a> + </li> + + <li> + <a href="#reset">Do I need to implement reset and set + all my form + properties to their initial values?</a> + </li> + + <li> + <a href="#scriptlets">Can't I just create some of my + JavaBeans in the JSP + using a scriptlet?</a> + </li> + + <li> + <a href="#link">Why does the <html:link> tag + URL-encode javascript and + mailto links?"</a> + </li> + + <li> + <a href="#pager">How can I scroll through list of + pages like the search + results in google?</a> + </li> + + <li> + <a href="#minimization">Why does the option tag render + selected="selected" + instead of just "selected"? + </a> + </li> + + <li> + <a href="#tags">Why does Struts Taglib provide for so + little + formatting?</a> + </li> + + <li> + <a href="#layout">Why doesn't Struts Taglib offer more + layout options?</a> + </li> + + </ul> + + </subsection> + + <a name="jsf"/> + <subsection name="What about JSTL and JavaServer Faces?"> + <p> + Struts Action Framework works well with the + <a href="http://java.sun.com/products/jsp/jstl/";> + JavaServer Standard Tag Library</a> + . + For a JSTL rendition of the original Struts JSP tags, + see the + <a href="http://struts.apache.org/struts-el/index.html";> + Struts EL subproject</a> + . + </p> + + <p> + If you'd like to start using + <a href="http://java.sun.com/j2ee/javaserverfaces/";> + JavaServer Faces</a> + components in your Struts Action Framework application, + please see the + <a href="http://struts.apache.org/struts-faces/index.html";> + Struts Faces</a> + subproject. + If you'd like to get a fresh start in a pure JSF + environment, + please see the + <a href="http://struts.apache.org/shale/index.html";>Struts + Shale</a> + framework. + </p> + </subsection> + + <a name="xhtml"/> + <subsection name="Are the Struts tags XHTML compliant?"> + <p>If you use an <html:html xhtml="true> or <html:xhtml/> + element on your page, the tags + will render as XHTML (since Struts 1.1).</p> + </subsection> + + <a name="wml"/> + <subsection + name="Will the Struts tags support other markup languages such as WML"> + <p> + Struts itself is markup neutral. The original Struts + taglibs are only one example of how + presentation layer components can access the framework. + The framework objects are exposed + through the standard application, session, and request + contexts, where any Java component in + the application can make use of them. + </p> + + <p>Markup extensions that use Struts are available for + <a href="http://jakarta.apache.org/velocity";>Velocity</a> + and + <a href="http://www.openroad.ca/opencode/";>XLST</a> + , among others. + A new Struts tag library for + <a href="#jsf">Java Server Faces</a> + is also in development. + </p> + + <p>For more about using WAP/WML with Struts see the article + <a href="http://www.sys-con.com/pbdj/archives2/0904/hamboeck/";> + WAP up your EAserver</a> + . + </p> + </subsection> + + <a name="multiple"/> + <subsection + name="Can I use multiple HTML form elements with the same name?"> + <p> + Yes. Define the element as an array and Struts will + autopopulate it like any other. + </p> + <pre> + <code> + private String[] id= {}; + public String[] getId() { return this.id; } + public void setItem(String id[]) {this.id = id;} + </code> + </pre> + <p> + And so forth + </p> + </subsection> + + <a name="multipleSubmits"/> + <subsection + name="Can I have multiple submit buttons on the same form?"> + <p> + <strong>Yes</strong> + . The issue is that only one action class can be + associated with a single form. So the real issue is how do + I decode + multiple submit types to a single + <code>Action</code> + class. + There is more than one way to achieve this functionality. + </p> + <p> + The way that is suggested by struts is right out of the + javadoc for + <a href="../api/org/apache/struts/actions/LookupDispatchAction.html"> + <code>LookupDispatchAction</code> + </a> + . + Basically, + <code>LookupDispatchAction</code> + is using the keys from + <code>ApplicationProperties.resources</code> + as keys to a map of actions + available to your + <code>Action</code> + class. It uses + <a href="http://java.sun.com/j2se/1.3/docs/guide/reflection/";> + reflection</a> + to + decode the request and invoke the proper action. It also + takes advantage of + the struts + <a href="../userGuide/struts-html.html#submit"> + <code><html:submit></code> + </a> + tags and is straight forward to implement. + </p> + <p> + You can roll your own with JavaScript events and + <code>javascript:void + (document.forms["myform"].submit)</code> + on any html element. This gives you + control of how you want your page to look. Again you + will have to decode the expected action in the + <code>execute</code> + method of + your action form if you choose this route. + </p> + </subsection> + + <a name="focus"/> + <subsection + name="Why doesn't the focus feature on the <html:form> tag work in every circumstance?"> + <p> + Unfortunately, there is some disagreement between the + various browsers, and different versions of the same + browser, as to how the focus can be set. + The <html:form> tag provides a quick and easy + JavaScript that will set the focus on a form + for most versions of most browsers. + If this feature doesn't work for you, then you should set + the focus using your own JavaScript. + The focus feature is a convenient "value-add" -- not a + core requirement of the tag. + If you do come up with a JavaScript that provides the + final solution to this project, + please post your patch to this + <a href="http://issues.apache.org/bugzilla/show_bug.cgi?id=13454";> + Bugzilla ticket</a> + . + </p> + </subsection> + + <a name="checkbox"/> + <subsection + name="Why are my checkboxes not being set from ON to OFF?"> + <p> + A problem with a checkbox is that the browser will only + include it in the request + when it is checked. If it is not checked, the HTML + specification suggests that it + not be sent (i.e. omitted from the request). If the value + of the checkbox is being + persisted, either in a session bean or in the model, a + checked box can never + unchecked by a HTML form -- because the form can never + send a signal to uncheck + the box. The application must somehow ascertain that since + the element was not + sent that the corresponding value is unchecked. + </p> + <p> + The recommended approach for Struts applications is to use + the reset method in the + ActionForm to set all properties represented by checkboxes + to null or false. The + checked boxes submitted by the form will then set those + properties to true. The + omitted properties will remain false. Another solution is + to use radio buttons + instead, which always submit a value. + </p> + <p> + It is important to note that the HTML specification + recommends this same + behavior whenever a control is not "successful". Any blank + element in a HTML + form is not guaranteed to submitted. It is therefor very + important to set the + default values for an ActionForm correctly, and to + implement the reset method + when the ActionForm might kept in session scope. + </p> + </subsection> + + <a name="javascript.submit"/> + <subsection name="Can I use JavaScript to submit a form?"> + <p> + You can submit a form with a link as below. + BTW, the examples below assume you are in an <html:form> + block and 'myForm' + is picked up from the struts-config.xml name field of the + action. + </p> + <source> + <a + href='javascript:void(document.forms["myForm"].submit()>My + Link</a> + </source> + <p> + Now the trick in the action is to decode what action you + intend to perform. + Since you are using JavaScript, you could set a field + value and look for it in + the request or in the form. + </p> + <p> + ... html/javascript part ... + </p> + <source> + <input type='hidden' value='myAction' /> + <input type='button' value='Save Meeeee' + onclick='document.forms["myForm"].myAction.value="save"; + document.forms["myForm"].submit();' /> + <input type='button' value='Delete Meeeee' + onclick='document.forms["myForm"].myAction.value="delete"; + document.forms["myForm"].submit();' /> + </source> + <p> + ... the java part ... + </p> + <source> + class MyAction extends ActionForm implements Serializable + { + + public ActionForward execute (ActionMapping map, + ActionForm form, + HttpServletRequest req, HttpServletResponse) { String myAction = req.getParameter("myAction"); if (myAction.equals("save") { - // ... save action ... + // ... save action ... } else if (myAction.equals("delete") { - // ... delete action ... + // ... delete action ... + } + } + } } - } - } - } -</source> -<p> - This is just one of many ways to achieve submitting a form and decoding the - intended action. Once you get used to the framework you will find other ways - that make more sense for your coding style and requirements. Just remember - this example is completely non-functional without JavaScript. -</p> -<p> - Here is a link - which utilizes the LookupDispatch action to submit forms with multiple actions - without javascript: <a href="http://husted.com/struts/tips/003.html";>http://husted.com/struts/tips/003.html</a> -</p> - -</subsection> - -<a name="javascript"/> -<subsection name="How do I use JavaScript to ..."> - - <p> - Struts is mainly a server-side technology. - We bundled in some JSP tags to expose the framework components to your - presentation page, but past that, the usual development process applies. - </p> - - <p> - Interactive pages require the use of JavaScript. - (That's why it was invented.) - If you want things popping up or doing this when they click that, - you are outside the scope of Struts and back into the web - development mainstream. - </p> - - <p> - You use JavaScript with Struts the same way you use with any presentation - page. - Since JavaScript is a client-side technology, you can use simple relative - references to your scripts. - If you need to fire a JavaScript from a HTML control, the Struts HTML tags - have properties for the JavaScript events. - </p> - - <p> - A very good JavaScript resource is Matt Kruse's site at - <a href="http://www.mattkruse.com/javascript/";> - http://www.mattkruse.com/javascript/</a> - </p> - -</subsection> - -<a name="reset"/> -<subsection name="Do I need to implement reset and set all my form properties to their initial values?"> -<p> -No. -You need to set checkbox properties to false if the ActionForm is being retained in session scope. -This is because an unchecked box does not submit an attribute. -Only checked boxes submit attributes. -If the form is in session scope, and the checkbox was checked, there is no way to turn it back off without the reset method. -Resetting the properties for other controls, or for a request scope form, is pointless. -If the form is in request scope, everything already just started at the initial value. -</p> -</subsection> - -<a name="scriptlets"/> -<subsection name="Can't I just create some of my JavaBeans in the JSP using a scriptlet?"> -<p> -Struts is designed to encourage a -<a href="http://www.javaworld.com/javaworld/jw-12-1999/jw-12-ssj-jspmvc.html";> -Model 2/MVC architecture</a>. But there is nothing that prevents you from using Model 1 -techniques in your JavaServer Pages, so the answer to the question is "Yes, you can". -</p> -<p> -Though, using Model 1 techniques in a Struts application does go against the grain. -The approach recommended by most Struts developers is to create and populate whatever -objects the view may need in the Action, and then forward these through the request. -Some objects may also be created and stored in the session or context, -depending on how they are used. -</p> -<p> -Likewise, there is nothing to prevent you from using scriptlets along with JSP -tags in your pages. Though, many Struts developers report writing very complex -scriplet-free applications and recommend the JSP tag approach to others. -</p> -<p> -For help with Model 1 techniques and scriptlets, you might consider joining the -<a href="http://archives.java.sun.com/jsp-interest.html";>Javasoft JSP-interest -mailing list</a>, where there are more people still using these approaches. -</p> -</subsection> - -<a name="link"/> -<subsection name="Why does the <html:link> tag URL-encode javascript and mailto links?"> -<p> -The <html:link> tag is not intended for use with client-side references like those used to launch Javascripts or email clients. -The purpose of link tag is to interject the context (or module) path into the URI so that your server-side links are not dependent on your context (or module) name. -It also encodes the link, as needed, to maintain the client's session on the server. -Neither feature applies to client-side links, so there is no reason to use the <html:link> tag. -Simply markup the client-side links using the standard <a/> tag. -</p> -</subsection> - -<a name="pager"/> -<subsection name="How can I scroll through list of pages like the search results in google?"> -<p>Many Struts developers use the Pager from the JSPTags site.</p> -<p><a href="http://jsptags.com/tags/navigation/pager/";>http://jsptags.com/tags/navigation/pager/</a></p> -</subsection> - -<a name="minimization"/> -<subsection name="Why does the option tag render selected=selected instead of just selected?"> -<p> -Attribute minimization (that is, specifying an attribute with no value) is -a place where HTML violates standard XML syntax rules. This matters a lot -for people writing to browsers that support XHTML, where doing so makes -the page invalid.It's much better for Struts to use the expanded syntax, -which works the same on existing browsers interpreting HTML, and newer -browsers that expect XHTML-compliant syntax. Struts is following the -behavior recommended by the <a href="http://www.w3.org/TR/xhtml1/#h-4.5";> -XHTML specification</a></p> -</subsection> - -<a name="tags"/> -<subsection name="Why does Struts Taglib provide for so little formatting?"> -<p> -<em>The Struts tags seem to provide only the most rudimentary functionality. -Why is there not better support for date formatting and advanced string handling?</em> -</p> -<p> -Three reasons: -</p> -<p> -First, work started on the JSTL and we didn't want to duplicate the effort. -</p> -<p> -Second, work started on Java Server Faces, and we didn't want to duplicate that effort either. -</p> -<p> -Third, in a Model 2 application, most of the formatting can be handled in the ActionForms (or in the business tier), -so all the tag has to do is spit out a string. -This leads to better reuse since the same "how to format" code does not need to be repeated in every instance. -You can "say it once" in a JavaBean and be done with it. -</p> -</subsection> - -<a name="layout"/> -<subsection name="Why doesn't Struts Taglib offer more layout options?"> -<p> -For more flexible placement of error messages, -try the <a href="http://www.rabago.net/struts/html2/";><html2></a> Tag Library for Struts. -</p> -<p> -Since the Struts tags are open source, you can extend them to provide whatever additional formatting you may need. -If you are interested in a pre-written taglib that offers more layout options, see the -<a href="http://struts.application-servers.com";>struts-layout taglib</a>. -</p> -<p> -In the same arena, there is a well regarded contributor taglib that can help you create -<a href="http://sourceforge.net/projects/struts-menu/";>Menus for your Struts applications</a>. -</p> -<p> -Another very popular tag library is <a href="http://displaytag.sourceforge.net";>DisplayTag</a>. -DisplayTag is an excellent choice when you have tabular data to present. -</p> -</subsection> - -<a name="undocumented"/> -<subsection - name="If you would like to contribute, here is a list of + </source> + <p> + This is just one of many ways to achieve submitting a form + and decoding the + intended action. Once you get used to the framework you + will find other ways + that make more sense for your coding style and + requirements. Just remember + this example is completely non-functional without + JavaScript. + </p> + <p> + Here is a link + which utilizes the LookupDispatch action to submit forms + with multiple actions + without javascript: + <a href="http://husted.com/struts/tips/003.html";> + http://husted.com/struts/tips/003.html</a> + </p> + + </subsection> + + <a name="javascript"/> + <subsection name="How do I use JavaScript to ..."> + + <p> + Struts is mainly a server-side technology. + We bundled in some JSP tags to expose the framework + components to your + presentation page, but past that, the usual development + process applies. + </p> + + <p> + Interactive pages require the use of JavaScript. + (That's why it was invented.) + If you want things popping up or doing this when they + click that, + you are outside the scope of Struts and back into the web + development mainstream. + </p> + + <p> + You use JavaScript with Struts the same way you use with + any presentation + page. + Since JavaScript is a client-side technology, you can use + simple relative + references to your scripts. + If you need to fire a JavaScript from a HTML control, the + Struts HTML tags + have properties for the JavaScript events. + </p> + + <p> + A very good JavaScript resource is Matt Kruse's site at + <a href="http://www.mattkruse.com/javascript/";> + http://www.mattkruse.com/javascript/</a> + </p> + + </subsection> + + <a name="reset"/> + <subsection + name="Do I need to implement reset and set all my form properties to their initial values?"> + <p> + No. + You need to set checkbox properties to false if the + ActionForm is being retained in session scope. + This is because an unchecked box does not submit an + attribute. + Only checked boxes submit attributes. + If the form is in session scope, and the checkbox was + checked, there is no way to turn it back off without the + reset method. + Resetting the properties for other controls, or for a + request scope form, is pointless. + If the form is in request scope, everything already just + started at the initial value. + </p> + </subsection> + + <a name="scriptlets"/> + <subsection + name="Can't I just create some of my JavaBeans in the JSP using a scriptlet?"> + <p> + Struts is designed to encourage a + <a href="http://www.javaworld.com/javaworld/jw-12-1999/jw-12-ssj-jspmvc.html";> + Model 2/MVC architecture</a> + . But there is nothing that prevents you from using Model + 1 + techniques in your JavaServer Pages, so the answer to the + question is "Yes, you can". + </p> + <p> + Though, using Model 1 techniques in a Struts application + does go against the grain. + The approach recommended by most Struts developers is to + create and populate whatever + objects the view may need in the Action, and then forward + these through the request. + Some objects may also be created and stored in the session + or context, + depending on how they are used. + </p> + <p> + Likewise, there is nothing to prevent you from using + scriptlets along with JSP + tags in your pages. Though, many Struts developers report + writing very complex + scriplet-free applications and recommend the JSP tag + approach to others. + </p> + <p> + For help with Model 1 techniques and scriptlets, you might + consider joining the + <a href="http://archives.java.sun.com/jsp-interest.html";> + Javasoft JSP-interest + mailing list</a> + , where there are more people still using these + approaches. + </p> + </subsection> + + <a name="link"/> + <subsection + name="Why does the <html:link> tag URL-encode javascript and mailto links?"> + <p> + The <html:link> tag is not intended for use with + client-side references like those used to launch + Javascripts or email clients. + The purpose of link tag is to interject the context (or + module) path into the URI so that your server-side links + are not dependent on your context (or module) name. + It also encodes the link, as needed, to maintain the + client's session on the server. + Neither feature applies to client-side links, so there is + no reason to use the <html:link> tag. + Simply markup the client-side links using the standard + <a/> + tag. + </p> + </subsection> + + <a name="pager"/> + <subsection + name="How can I scroll through list of pages like the search results in google?"> + <p>Many Struts developers use the Pager from the JSPTags + site.</p> + <p> + <a href="http://jsptags.com/tags/navigation/pager/";> + http://jsptags.com/tags/navigation/pager/</a> + </p> + </subsection> + + <a name="minimization"/> + <subsection + name="Why does the option tag render selected=selected instead of just selected?"> + <p> + Attribute minimization (that is, specifying an attribute + with no value) is + a place where HTML violates standard XML syntax rules. + This matters a lot + for people writing to browsers that support XHTML, where + doing so makes + the page invalid.It's much better for Struts to use the + expanded syntax, + which works the same on existing browsers interpreting + HTML, and newer + browsers that expect XHTML-compliant syntax. Struts is + following the + behavior recommended by the + <a href="http://www.w3.org/TR/xhtml1/#h-4.5";> + XHTML specification</a> + </p> + </subsection> + + <a name="tags"/> + <subsection + name="Why does Struts Taglib provide for so little formatting?"> + <p> + <em>The Struts tags seem to provide only the most + rudimentary functionality. + Why is there not better support for date formatting + and advanced string handling?</em> + </p> + <p> + Three reasons: + </p> + <p> + First, work started on the JSTL and we didn't want to + duplicate the effort. + </p> + <p> + Second, work started on Java Server Faces, and we didn't + want to duplicate that effort either. + </p> + <p> + Third, in a Model 2 application, most of the formatting + can be handled in the ActionForms (or in the business + tier), + so all the tag has to do is spit out a string. + This leads to better reuse since the same "how to format" + code does not need to be repeated in every instance. + You can "say it once" in a JavaBean and be done with it. + </p> + </subsection> + + <a name="layout"/> + <subsection + name="Why doesn't Struts Taglib offer more layout options?"> + <p> + For more flexible placement of error messages, + try the + <a href="http://www.rabago.net/struts/html2/";><html2></a> + Tag Library for Struts. + </p> + <p> + Since the Struts tags are open source, you can extend them + to provide whatever additional formatting you may need. + If you are interested in a pre-written taglib that offers + more layout options, see the + <a href="http://struts.application-servers.com";> + struts-layout taglib</a> + . + </p> + <p> + In the same arena, there is a well regarded contributor + taglib that can help you create + <a href="http://sourceforge.net/projects/struts-menu/";> + Menus for your Struts applications</a> + . + </p> + <p> + Another very popular tag library is + <a href="http://displaytag.sourceforge.net";>DisplayTag</a> + . + DisplayTag is an excellent choice when you have tabular + data to present. + </p> + </subsection> + + <a name="undocumented"/> + <subsection + name="If you would like to contribute, here is a list of popular but undocumented questions"> - <ul> + <ul> - <li>Why do my option lists disappear when validation fails?</li> + <li>Why do my option lists disappear when validation + fails?</li> - <li>Why can't I disable URL-encoding in the Struts taglibs?</li> + <li>Why can't I disable URL-encoding in the Struts + taglibs?</li> - </ul> -</subsection> + </ul> + </subsection> -</section></body></document> + </section> + </body> +</document>
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