mentioning actions twice in struts-config

[Rauhl Roy]

Hi all,

My specs suggest two actions for one JSP, may i know why should i write like that?

ex:

sample diagram is like this:

|----- showCustomerPaymentDataChangeStart.do
| |
fail |
| JSP Name here
| |
| |{logged_in}
| |
-------- CustomerPaymentDataChange.do


may i know what is the use of writing the actions twice in struts-config.xml file.

regards,
rahul

[Merrill Higginson]

Most JSPs require some sort of preparation before they can be displayed such as populating lists for dropdown boxes, getting user information from a database, etc. If the JSP contains an HTML form as most do, there is also an action that must be taken when the form is submitted. Hence, there is often a need for two actions for every JSP: One to prepare for the display of the JSP, and one to process the information entered by the user in an HTML form.

[Vyas Sanzgiri]

2 different actions - 2 different entries.

[Rauhl Roy]

Originally posted by Merrill Higginson:
Most JSPs require some sort of preparation before they can be displayed such as populating lists for dropdown boxes, getting user information from a database, etc. If the JSP contains an HTML form as most do, there is also an action that must be taken when the form is submitted. Hence, there is often a need for two actions for every JSP: One to prepare for the display of the JSP, and one to process the information entered by the user in an HTML form.

can i get a simple example for this please?

[Merrill Higginson]

Form bean:

public class ColorForm extends ActionForm {
private String[] colors;
private String selectedColor;
        // getters and setters
}

Action classes:

public class PrepareColorAction extends Action {
public static final String[] COLORS = {"red", "green", "blue", "yellow"};
 
@Override
public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception {
ColorForm colorForm = (ColorForm)form;
                // normally you'd get the list from a database,
                // but I'm using a static variable here for simplicity
colorForm.setColors(COLORS);
return mapping.findForward("success");
}
 
}
 
 
public class ProcessColorAction extends Action {
 
@Override
public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception {
ColorForm colorForm = (ColorForm)form;
// here is where you put the code to save the selected color to a database
System.out.println("Color Chosen:"+colorForm.getSelectedColor());
return mapping.findForward("success");
}
 
}

struts-config.xml

    <form-beans>
    <form-bean
       name="colorForm"
       type="org.merrill.forms.ColorForm"
       />
    </form-beans>
 
    <action-mappings>
        <action 
        path="/prepareColor"
        name="colorForm"
        scope="request"
        type="org.merrill.actions.PrepareColorAction"
        >
        <forward name="success" path="/ColorSelect.jsp" />
        </action>
        <action 
        path="/processColor"
        name="colorForm"
        scope="request"
        type="org.merrill.actions.ProcessColorAction"
        >
        <forward name="success" path="/ColorResult.jsp" />
        </action>
 
    </action-mappings>

ColorSelect.jsp

<h1>Select your favorite color</h1>
<html:form action="/processColor">
<p>My favorite color is:
<html:select property="selectedColor" >
<html:options property="colors" />
</html:select>
<br><html:submit value="save" />
 </p>
</html:form>

ColorResult.jsp

<p>The color you selected is <bean:write name="colorForm" property="selectedColor" />

[ June 20, 2007: Message edited by: Merrill Higginson ]

[Rauhl Roy]

thanks alot Mr. Merrill Higginson
this example is a very good example

regards,
rahul

[Rauhl Roy]

found a problem in Mr. Merrill Higginson code.

after running this code implementing the back and next buttons.

when i use back button from the last jsp to privious jsp, the value I select from the list is not appearing.

May i know what should i do to solve this problem.

and the big question is if I have more than one list box which should always show the selected iteams whn i come back from the other pages i think this code has to be modified.

please suggest me
regards,

rahul

[Merrill Higginson]

Bear in mind that this code was written as a simple demo, not a complete application. It has no database persistence, which is something you'd naturally want to put in an actual application.

In order to have the value selected retained, you would have to actually save the value to a database and then retrieve it when the page is redisplayed. In the example, you would add the following lines to the PrepareColorAction class:

// get the value from the database.  UserDao has a static method that gets the
// favorite color value from the database given the user id
colorForm.setSelectedColor(UserDao.getFavoriteColor(theUser));

You'd then add the following code to the ProcessColorAction class:

// save the value to the database.  UserDao has a static method that
// saves the favorite color for the current user
UserDao.saveFavoriteColor(theUser, colorForm.getSelectedColor());

[Rauhl Roy]

thank you very much Mr. Merrill Higginson for your indetailed reply.

And it seems we are supposed to create an onther class which gets and sets color. I think, even though UserDao is not a form bean it resembels like it.


Thnks and regards,
rahul