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Posted to users@tomcat.apache.org by Piotr Kiraga <pi...@gmail.com> on 2007/02/20 12:53:23 UTC
Expression Language in JSP and JasperException
Hi,
When I'm using in JSP:
<c:if test="${actionBean.result != null}">...</c:if>
Tomcat (5.5.17) throws exception (javax.servlet.ServletException:
Unable to find a value for "result" in object of class
"com.some.packages.action.LoginActionBean" using operator ".").
I've heard that it can be configured in Tomcat, so he could pass
through it without an exception. Is it true? If so, how to do that?
Regards,
--
Piotr Kiraga
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Re: Expression Language in JSP and JasperException
Posted by Eric Haszlakiewicz <er...@swapsimple.com>.
On Tue, Feb 20, 2007 at 03:23:32PM -0500, David Smith wrote:
> Ok .... forgive me now, but this is getting confusing. Where does
> result come into this picture? Were you expecting actionBean to be an
> instance of a different class? You aren't offering a lot to go on here.
That's what it sounds like to me:
> Piotr Kiraga wrote:
> >>> The problem is that there could be a class that has no property with
> >>> name result. In another case there could be another class (bean) that
> >>> has such property (than of course it works fine, but at first case
> >>> Tomcat throws exception).
I actually have some jsp code that does stuff like this, but in my case
there is a "type" property that each object has. I check that and do
the appropriate thing.
If you want to hard code a class name in your jsp page, you can just use
${foo.class.name} to figure out what type of object you have.
Or, if you want to get really crazy you could loop over ${foo.class.methods}
checking if there's a method named "getResult".
But, you'd probably be better off figuring out way to ensure the objects
you're working with have a "result" property.
eric
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Re: Expression Language in JSP and JasperException
Posted by David Smith <dn...@cornell.edu>.
Ok. I'm not overly familiar with Stripes, so you'll have to bear with
me a little. I can think of a few ways to handle this.
First, look at what makes a request from calculator.jsp unique. You
could use the referrer header, the value of a submit button, or the
presence of the equation request parameter. Below is an example using
the submit button:
<c:if test="${(param.submitBtn == 'Calculate') and (actionBean.result !=
null)}">
<p>The answer is ${actionBean.result}</p>
</c:if>
A better solution would be to name the actionBean that's a result of
CalculatorActionBean something more descript than just 'actionBean' like
'calcBean'. The main advantage here is it's simple and you could use
your original expression language test -- just change the name of the
object being tested:
<c:if test="${calcBean.result != null}">
... display the result....
</c:if>
A more complicated solution if you can't change the name of 'actionBean'
might be to test the type of actionBean like...
<c:set var="calcAvailable"><jsp:expression>
(request.getAttribute("actionBean") != null) &&
(request.getAttribute("actionBean") instanceOf
com.some.packages.action.CalculatorActionBean )</jsp:expression></c:set>
<c:choose>
<c:when test="${calcAvailable and (actionBean.result != null)}">
<p>The answer is .... ${actionBean.result}</p>
</c:when>
<c:when test="${calcAvailable}">
<p>Sorry, I couldn't understand your equation. Please rephrase it...</p>
</c:when>
<c:otherwise>
<!-- Just logged in. Display the form. -->
</c:otherwise>
</c:choose>
The essential point of this is testing for a property to be null is not
the same as testing for it's presence. You'll have to know if it has a
property before you can test the property for null.
--David
Piotr Kiraga wrote:
> Hi David,
>
>> Ok .... forgive me now, but this is getting confusing. Where does
>> result come into this picture? Were you expecting actionBean to be an
>> instance of a different class? You aren't offering a lot to go on here.
>
>
> Sorry for mixup. I've just thought that it is just about some option
> in Tomcat configuration or something, and I haven't knew it. Like I
> see... It may be not. :(
>
> Here goes more background.
>
> login.jsp (handled by LoginActionBean class) redirects after
> submission login form to calculator.jsp. After submition form from
> calculator.jsp (what is handled by CalculatorActionBean class) it
> returns to calculator.jsp and shows the result of mathematical
> equation. Sources of calculator.jsp and it's class are placed below.
>
> Problem shows when I'm submiting from LoginActionVean to
> calculator.jsp. Like I wrote before, LoginActionBean doesn't have
> result field because it doesn't need it. But JSP (in this case used by
> two classes) expects result in:
> 46: <c:if test="${!empty actionBean.result}">
> 47: Result: ${actionBean.result}<br/>
> line.
>
> Here actionBean could be an instance of different class.
>
> Sorry for so much source in thread, here it goes:
>
>
>
>
> #########################
> package com.some.packages.action;
>
> import net.sourceforge.stripes.action.ActionBean;
> import net.sourceforge.stripes.action.ActionBeanContext;
> import net.sourceforge.stripes.action.DefaultHandler;
> import net.sourceforge.stripes.action.DontValidate;
> import net.sourceforge.stripes.action.ForwardResolution;
> import net.sourceforge.stripes.action.Resolution;
> import net.sourceforge.stripes.validation.LocalizableError;
> import net.sourceforge.stripes.validation.Validate;
> import net.sourceforge.stripes.validation.ValidationErrors;
> import net.sourceforge.stripes.validation.ValidationMethod;
>
> /**
> * A very simple calculator action.
> * @author Tim Fennell
> */
>
> public class CalculatorActionBean implements ActionBean {
>
> private ActionBeanContext context;
> private String forwardSuccess = "/calculator.jsp";
> private String forwardFail = "/index.jsp";
>
> private Double result;
> @Validate(required=true, mask="^\\d*$") private double numberOne;
> @Validate(required=true, mask="^\\d*$") private double numberTwo;
>
> public CalculatorActionBean() {
> }
>
> /***** execution *****/
>
> /*
> * Handler method.
> * Handles addition functionality of web application form.
> */
> @DefaultHandler
> @DontValidate
> public Resolution init() {
> return new ForwardResolution(forwardSuccess);
> }
>
> /*
> * Handler method.
> * Handles addition functionality of web application form.
> */
> public Resolution addition() {
> result = getNumberOne() + getNumberTwo();
> return new ForwardResolution(forwardSuccess);
> }
>
> /***** getters and setters *****/
>
> public ActionBeanContext getContext() {
> return context;
> }
>
> public void setContext(ActionBeanContext context) {
> this.context = context;
> }
>
> public double getNumberOne() {
> return numberOne;
> }
>
> public void setNumberOne(double numberOne) {
> this.numberOne = numberOne;
> }
>
> public double getNumberTwo() {
> return numberTwo;
> }
>
> public void setNumberTwo(double numberTwo) {
> this.numberTwo = numberTwo;
> }
>
> public Double getResult() {
> return result;
> }
>
> public void setResult(Double result) {
> this.result = result;
> }
>
> }
> #########################
>
>
>
>
> #########################
> <%@ page contentType="text/html;charset=UTF-8" language="java" %>
> <%@ taglib prefix="stripes"
> uri="http://stripes.sourceforge.net/stripes.tld"%>
> <%@ taglib prefix="display" uri="http://displaytag.sf.net"%>
> <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
> <%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
> <fmt:setBundle basename="StripesResources"/>
>
> <stripes:layout-render name="/pages/layout/default.jsp">
>
> <stripes:layout-component name="contents">
>
> <h3><fmt:message key="title" /> - <fmt:message
> key="title.calculator"/></h3>
>
> <stripes:errors />
>
> <stripes:form action="/Calculator.action" focus="">
>
> <table>
> <tr>
> <td>
> <div>
> <div style="width:150px;"><stripes:label
> for="numberOne"/></div>
> <div style="display:inline"><stripes:text
> name="numberOne"/></div>
> </div>
> <div>
> <div style="width:150px;"><stripes:label
> for="numberTwo"/></div>
> <div style="display:inline"><stripes:text
> name="numberTwo"/></div>
> </div>
> </td>
> <td valign="bottom">
> <div>
> <stripes:submit name="addition"/>
> <stripes:submit name="subtraction"/>
> <stripes:submit name="multiplication"/>
> <stripes:submit name="division"/>
> <div>
> </td>
> </tr>
> </table>
>
> </stripes:form>
>
> <br/>
>
> <hr size="1" noshade color="#000" align="left"><br/>
> <c:if test="${!empty actionBean.result}">
> Result: ${actionBean.result}<br/>
> </c:if>
> <c:if test="${!empty sessionScope.user.userName}">
> Logged in as: ${sessionScope.user.firstName}
> ${sessionScope.user.lastName} (${sessionScope.user.userName})<br/>
> </c:if>
>
> </stripes:layout-component>
>
> </stripes:layout-render>
> #########################
>
>
>
>
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Re: Expression Language in JSP and JasperException
Posted by Piotr Kiraga <pi...@gmail.com>.
Hi David,
> Ok .... forgive me now, but this is getting confusing. Where does
> result come into this picture? Were you expecting actionBean to be an
> instance of a different class? You aren't offering a lot to go on here.
Sorry for mixup. I've just thought that it is just about some option
in Tomcat configuration or something, and I haven't knew it. Like I
see... It may be not. :(
Here goes more background.
login.jsp (handled by LoginActionBean class) redirects after
submission login form to calculator.jsp. After submition form from
calculator.jsp (what is handled by CalculatorActionBean class) it
returns to calculator.jsp and shows the result of mathematical
equation. Sources of calculator.jsp and it's class are placed below.
Problem shows when I'm submiting from LoginActionVean to
calculator.jsp. Like I wrote before, LoginActionBean doesn't have
result field because it doesn't need it. But JSP (in this case used by
two classes) expects result in:
46: <c:if test="${!empty actionBean.result}">
47: Result: ${actionBean.result}<br/>
line.
Here actionBean could be an instance of different class.
Sorry for so much source in thread, here it goes:
#########################
package com.some.packages.action;
import net.sourceforge.stripes.action.ActionBean;
import net.sourceforge.stripes.action.ActionBeanContext;
import net.sourceforge.stripes.action.DefaultHandler;
import net.sourceforge.stripes.action.DontValidate;
import net.sourceforge.stripes.action.ForwardResolution;
import net.sourceforge.stripes.action.Resolution;
import net.sourceforge.stripes.validation.LocalizableError;
import net.sourceforge.stripes.validation.Validate;
import net.sourceforge.stripes.validation.ValidationErrors;
import net.sourceforge.stripes.validation.ValidationMethod;
/**
* A very simple calculator action.
* @author Tim Fennell
*/
public class CalculatorActionBean implements ActionBean {
private ActionBeanContext context;
private String forwardSuccess = "/calculator.jsp";
private String forwardFail = "/index.jsp";
private Double result;
@Validate(required=true, mask="^\\d*$") private double numberOne;
@Validate(required=true, mask="^\\d*$") private double numberTwo;
public CalculatorActionBean() {
}
/***** execution *****/
/*
* Handler method.
* Handles addition functionality of web application form.
*/
@DefaultHandler
@DontValidate
public Resolution init() {
return new ForwardResolution(forwardSuccess);
}
/*
* Handler method.
* Handles addition functionality of web application form.
*/
public Resolution addition() {
result = getNumberOne() + getNumberTwo();
return new ForwardResolution(forwardSuccess);
}
/***** getters and setters *****/
public ActionBeanContext getContext() {
return context;
}
public void setContext(ActionBeanContext context) {
this.context = context;
}
public double getNumberOne() {
return numberOne;
}
public void setNumberOne(double numberOne) {
this.numberOne = numberOne;
}
public double getNumberTwo() {
return numberTwo;
}
public void setNumberTwo(double numberTwo) {
this.numberTwo = numberTwo;
}
public Double getResult() {
return result;
}
public void setResult(Double result) {
this.result = result;
}
}
#########################
#########################
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="stripes" uri="http://stripes.sourceforge.net/stripes.tld"%>
<%@ taglib prefix="display" uri="http://displaytag.sf.net"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<fmt:setBundle basename="StripesResources"/>
<stripes:layout-render name="/pages/layout/default.jsp">
<stripes:layout-component name="contents">
<h3><fmt:message key="title" /> - <fmt:message
key="title.calculator"/></h3>
<stripes:errors />
<stripes:form action="/Calculator.action" focus="">
<table>
<tr>
<td>
<div>
<div style="width:150px;"><stripes:label
for="numberOne"/></div>
<div style="display:inline"><stripes:text
name="numberOne"/></div>
</div>
<div>
<div style="width:150px;"><stripes:label
for="numberTwo"/></div>
<div style="display:inline"><stripes:text
name="numberTwo"/></div>
</div>
</td>
<td valign="bottom">
<div>
<stripes:submit name="addition"/>
<stripes:submit name="subtraction"/>
<stripes:submit name="multiplication"/>
<stripes:submit name="division"/>
<div>
</td>
</tr>
</table>
</stripes:form>
<br/>
<hr size="1" noshade color="#000" align="left"><br/>
<c:if test="${!empty actionBean.result}">
Result: ${actionBean.result}<br/>
</c:if>
<c:if test="${!empty sessionScope.user.userName}">
Logged in as: ${sessionScope.user.firstName}
${sessionScope.user.lastName} (${sessionScope.user.userName})<br/>
</c:if>
</stripes:layout-component>
</stripes:layout-render>
#########################
--
Piotr Kiraga
K i r a g a d e s i g n
+48 693 104 834
http://www.kiragadesign.pl/
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Re: Expression Language in JSP and JasperException
Posted by David Smith <dn...@cornell.edu>.
Ok .... forgive me now, but this is getting confusing. Where does
result come into this picture? Were you expecting actionBean to be an
instance of a different class? You aren't offering a lot to go on here.
--David
Piotr Kiraga wrote:
>> > The problem is that there could be a class that has no property with
>> > name result. In another case there could be another class (bean) that
>> > has such property (than of course it works fine, but at first case
>> > Tomcat throws exception).
>> >
>> Maybe.... but let's keep debugging simple. The expression language is
>> expecting a class conforming to the JavaBeans standard. What does the
>> class "com.some.packages.action.LoginActionBean" look like?
>
> Here is LoginActionBean class code (like I sad before, there is no
> result field, so getter and seter either):
>
> ################################################
> package com.some.packages.action;
>
> import net.sourceforge.stripes.action.ActionBean;
> import net.sourceforge.stripes.action.ActionBeanContext;
> import net.sourceforge.stripes.action.DefaultHandler;
> import net.sourceforge.stripes.action.DontValidate;
> import net.sourceforge.stripes.action.ForwardResolution;
> import net.sourceforge.stripes.action.Resolution;
> import net.sourceforge.stripes.validation.LocalizableError;
> import net.sourceforge.stripes.validation.Validate;
>
> import com.some.packages.util.Global;
> import com.some.packages.util.SessionManager;
> import com.some.packages.vo.UserVO;
>
> /**
> * @author Piotr Kiraga
> * @since 2007-02-15 12:13:06
> */
> public class LoginActionBean implements ActionBean {
>
> private ActionBeanContext context;
> private String forwardSuccess = "/calculator.jsp";
> private String forwardFail = "/index.jsp";
>
> @Validate(required=true, mask="^.{4,8}$") private String userName;
> @Validate(required=true, mask="^.{1,8}$") private String password;
>
> /* execute
> *************************************************************************/
>
>
> /*
> * Handler method.
> * Handles default action.
> */
> @DefaultHandler
> @DontValidate
> public Resolution init() {
> return new ForwardResolution(forwardFail);
> }
>
> /*
> * Handler method.
> * Handles login action.
> */
> public Resolution login() {
> if ( SessionManager.authorize(getContext(), getUserName(),
> getPassword()) ) {
> return new ForwardResolution(forwardSuccess);
> }
> else {
> this.getContext().getValidationErrors().addGlobalError(new
> LocalizableError("login.error.invalidUserOrPass", userName));
> return init();
> }
> }
>
> /* validation
> **********************************************************************/
>
> /* getters and setters
> *************************************************************/
>
> public String getPassword() {
> return password;
> }
>
> public void setPassword(String password) {
> this.password = password;
> }
>
> public String getUserName() {
> return userName;
> }
>
> public void setUserName(String userName) {
> this.userName = userName;
> }
>
> public ActionBeanContext getContext() {
> return context;
> }
>
> public void setContext(ActionBeanContext context) {
> this.context = context;
> }
>
> }
> ################################################
>
>
> Regards,
>
--
David Smith
Network Operations Supervisor
Department of Entomology
Cornell University
2132 Comstock Hall
Ithaca, NY 14853
Phone: (607) 255-9571
Fax: (607) 255-0940
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Re: Expression Language in JSP and JasperException
Posted by Piotr Kiraga <pi...@gmail.com>.
> > The problem is that there could be a class that has no property with
> > name result. In another case there could be another class (bean) that
> > has such property (than of course it works fine, but at first case
> > Tomcat throws exception).
> >
> Maybe.... but let's keep debugging simple. The expression language is
> expecting a class conforming to the JavaBeans standard. What does the
> class "com.some.packages.action.LoginActionBean" look like?
Here is LoginActionBean class code (like I sad before, there is no
result field, so getter and seter either):
################################################
package com.some.packages.action;
import net.sourceforge.stripes.action.ActionBean;
import net.sourceforge.stripes.action.ActionBeanContext;
import net.sourceforge.stripes.action.DefaultHandler;
import net.sourceforge.stripes.action.DontValidate;
import net.sourceforge.stripes.action.ForwardResolution;
import net.sourceforge.stripes.action.Resolution;
import net.sourceforge.stripes.validation.LocalizableError;
import net.sourceforge.stripes.validation.Validate;
import com.some.packages.util.Global;
import com.some.packages.util.SessionManager;
import com.some.packages.vo.UserVO;
/**
* @author Piotr Kiraga
* @since 2007-02-15 12:13:06
*/
public class LoginActionBean implements ActionBean {
private ActionBeanContext context;
private String forwardSuccess = "/calculator.jsp";
private String forwardFail = "/index.jsp";
@Validate(required=true, mask="^.{4,8}$") private String userName;
@Validate(required=true, mask="^.{1,8}$") private String password;
/* execute *************************************************************************/
/*
* Handler method.
* Handles default action.
*/
@DefaultHandler
@DontValidate
public Resolution init() {
return new ForwardResolution(forwardFail);
}
/*
* Handler method.
* Handles login action.
*/
public Resolution login() {
if ( SessionManager.authorize(getContext(), getUserName(), getPassword()) ) {
return new ForwardResolution(forwardSuccess);
}
else {
this.getContext().getValidationErrors().addGlobalError(new
LocalizableError("login.error.invalidUserOrPass", userName));
return init();
}
}
/* validation **********************************************************************/
/* getters and setters
*************************************************************/
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public ActionBeanContext getContext() {
return context;
}
public void setContext(ActionBeanContext context) {
this.context = context;
}
}
################################################
Regards,
--
Piotr Kiraga
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Re: Expression Language in JSP and JasperException
Posted by David Smith <dn...@cornell.edu>.
Piotr Kiraga wrote:
>> Does com.some.packages.action.LoginActionBean have a public method
>> getResult()? The test below effectively translates to:
>>
>> if (actionBean.getResult() != null) {
>> // .... some stuff to do ....
>> }
>
> The problem is that there could be a class that has no property with
> name result. In another case there could be another class (bean) that
> has such property (than of course it works fine, but at first case
> Tomcat throws exception).
>
Maybe.... but let's keep debugging simple. The expression language is
expecting a class conforming to the JavaBeans standard. What does the
class "com.some.packages.action.LoginActionBean" look like?
--David
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Re: Expression Language in JSP and JasperException
Posted by Piotr Kiraga <pi...@gmail.com>.
> Does com.some.packages.action.LoginActionBean have a public method
> getResult()? The test below effectively translates to:
>
> if (actionBean.getResult() != null) {
> // .... some stuff to do ....
> }
The problem is that there could be a class that has no property with
name result. In another case there could be another class (bean) that
has such property (than of course it works fine, but at first case
Tomcat throws exception).
--
Piotr Kiraga
---------------------------------------------------------------------
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Re: Expression Language in JSP and JasperException
Posted by David Smith <dn...@cornell.edu>.
Does com.some.packages.action.LoginActionBean have a public method
getResult()? The test below effectively translates to:
if (actionBean.getResult() != null) {
// .... some stuff to do ....
}
--David
Piotr Kiraga wrote:
> Hi,
>
> When I'm using in JSP:
> <c:if test="${actionBean.result != null}">...</c:if>
> Tomcat (5.5.17) throws exception (javax.servlet.ServletException:
> Unable to find a value for "result" in object of class
> "com.some.packages.action.LoginActionBean" using operator ".").
>
> I've heard that it can be configured in Tomcat, so he could pass
> through it without an exception. Is it true? If so, how to do that?
>
>
> Regards,
>
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