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Pass an arraylist from Action to JSP

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s4sudha

s4sudha

Programmer
Nov 10, 2003
3
IN
hi pple

am a struts-beginner and i need help on passing an Arraylist frm Action to JSP.

-- users access ContactPage.jsp
-- present text boxes and a combo box with values loaded from DB

-- SetUpMessageAction is called when ContactPage.jsp is called and i load an arraylist here
-- next, i need send the arraylist to ContactPage.jsp

i cud use Session or request.setAttribute ( ) to get this done. but i am sure there is a 'struts-way' of doing this.

in the execute ( ) of SetUpMessageAction, i have:

Code: 
MessageService service = new MessageService ( ) ;
DynaActionForm messageForm = ( DynaActionForm ) form ;
Collection categories = service.getCategories ( ) ;
request.setAttribute ( mapping.getAttribute ( ), messageForm ) ;
return ( mapping.findForward ( "continue" ) ) ;


i have a CategoryBean with int id, String description. in service.getCategories ( ), i do

Code: 
 list.add ( new CategoryBean ( 1, "Accounting" ) ) ;
repeatedly to populate the Arraylist. This is supposed to make a 'select' from the DB. For now, i populate it manually.


from Action, request is fwd-ed to ContactPage.jsp, where I need to get the 'categories' collection to populate my combo box.

this is how i try to populate the combo box:


Code: 
<html:select name=&quot;messageForm&quot; property=&quot;category_id&quot;>     <html  ptions collection=&quot;categories&quot; property=&quot;id&quot;    labelProperty=&quot;description&quot;/></html:select>

in my struts-config.xml, this is wht i have:

Code: 
<form-beans>        
<form-bean  name=&quot;messageForm&quot;                    
                   dynamic=&quot;true&quot; 
                   type=&quot;org.apache.struts.validator.DynaValidatorForm&quot;> 
      <form-property name=&quot;name&quot; type=&quot;java.lang.String&quot;/>            
      <form-property name=&quot;email&quot; type=&quot;java.lang.String&quot;/>            
      <form-property name=&quot;category_id&quot; type=&quot;java.lang.String&quot;/>            
      <form-property name=&quot;message&quot; type=&quot;java.lang.String&quot;/>        
 </form-bean>    
</form-beans>

the exception i get is:


Code: 
exception javax.servlet.ServletException: Cannot find bean under name categories     org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:673)     org.apache.jsp.ContactForm_jsp._jspService(ContactForm_jsp.java:227)     org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:133)     javax.servlet.http.HttpServlet.service(HttpServlet.java:856)     org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:311)     org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:301)     org.apache.jasper.servlet.JspServlet.service(JspServlet.java:248)     javax.servlet.http.HttpServlet.service(HttpServlet.java:856)root cause javax.servlet.jsp.JspException: Cannot find bean under name categories     org.apache.struts.taglib.html.OptionsTag.getIterator(OptionsTag.java:407)     org.apache.struts.taglib.html.OptionsTag.doEndTag(OptionsTag.java:232)     org.apache.jsp.ContactForm_jsp._jspx_meth_html_options_0(ContactForm_jsp.java:460)     org.apache.jsp.ContactForm_jsp._jspx_meth_html_select_0(ContactForm_jsp.java:433)     org.apache.jsp.ContactForm_jsp._jspx_meth_html_form_0(ContactForm_jsp.java:358)     org.apache.jsp.ContactForm_jsp._jspService(ContactForm_jsp.java:217)     org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:133)     javax.servlet.http.HttpServlet.service(HttpServlet.java:856)     org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:311)     org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:301)     org.apache.jasper.servlet.JspServlet.service(JspServlet.java:248)     javax.servlet.http.HttpServlet.service(HttpServlet.java:856)

what does that mean? am i not setting 'categories' explicitly in Action? what am i missing here?

thanks a ton.

-- $uDhA
 
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request.setAttribute is the correct way of passing object from action class to JSP.

In your execute() method of your SetUpMessageAction class,

ArrayList list = new ArrayList();
list.add(new CategoryBean ( 1, &quot;Accounting&quot; ) ) ;
list.add(new CategoryBean ( 2, &quot;Housekeeping&quot; ) ) ;
......

request.setAttribute(&quot;categories&quot;, list);
// 'categories' would be the bean name in JSP

return mapping.findForward ( &quot;continue&quot; );

assuming in your struts.config file, you have the SetUpMessageAction mapped as:

<action path=&quot;setupMessage&quot;
type=&quot;yourPackage.SetUpMessageAction&quot;
name=&quot;messageForm&quot;>
<forward name=&quot;continues&quot; path=&quot;/setup.jsp&quot;/>
</action>

and you have another class SetupMessageSubmitAction will handle the busincess logic for the submitted form. And in your struts.config you will have:

<action path=&quot;/setupMessage&quot;
type=&quot;yourPackage.SetUpMessageSubmitAction&quot;
name=&quot;messageForm&quot;>
<forward name=&quot;continues&quot; path=&quot;/setup.jsp&quot;/>
</action>

<action path=&quot;/setupMessageSubmit&quot;
type=&quot;...SetUpMessageSubmitAction&quot;
name=&quot;messageForm&quot;>
<forward name=&quot;continues&quot; path=&quot;/setup_confirm.jsp&quot;/>
</action>

Then in the setup.jsp page you would have something like:

<html:form action=&quot;/setupMessageSubmit&quot;>
<html:select property=&quot;category_id&quot;>
<html:eek:ptions collection=&quot;categories&quot; property=&quot;id&quot; labelProperty=&quot;description&quot;/>
</html:select>





 
Upvote 0 Downvote

hi byam:

thanks for the response.

but isnt that exactly what am doing??

in execute() of SetUpMessageAction class:

Code: 
ArrayList categories = service.getCategories ( ) ;
request.setAttribute ( &quot;categories&quot;, categories ) ;
return ( mapping.findForward ( &quot;continue&quot; ) ) ;

in struts-config.xml:
Code: 
<action path=&quot;/setUpMessageForm&quot;
            type=&quot;net.pilot.SetUpMessageAction&quot;
            name=&quot;messageForm&quot;
            scope=&quot;request&quot;
            validate=&quot;false&quot;>
            <forward
                    name=&quot;continue&quot;
                    path=&quot;/ContactForm.jsp&quot;/>
</action>

i don't need an intermediate 'SetupMessageSubmitAction' class.

in my JSP:

Code: 
 <html:select property=&quot;category_id&quot;>
      <html:options
                 collection=&quot;categories&quot;
                 property=&quot;id&quot;
                 labelProperty=&quot;description&quot;/>

why am i still getting the error????

Code: 
javax.servlet.ServletException: Cannot find bean under name categories

please help.

thanks again
-- $uDhA
 
Upvote 0 Downvote
I tested the code. It works. Are you sure that your service.getCategories ( ) is not returning null?
 
Upvote 0 Downvote
thanks for the response.

i copied all my files to another directory and worked frm this new folder. and it works now. its absolutely crazy and ended up losing 2 days of work and a lot of sleep!

thanks again
-- $uDhA
 
Upvote 0 Downvote
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