Expression Language - Help

I'm a new-comer to the expression language and have found it very hard to get to grips with it! Is there any books or manual that exist out there to help a newby like myself?

Welcome to the club my friend!
I like you was looking everywhere for some additional examples and definitions to bridge the gaps but found nearly nothing out in the real world through Google searches or other IT web forums. Siebel provides very few examples and the documentation reminds me of Windows help in the early nineties (overall not very helpful).
Since then I've just focused on hacking my way through the darkness and just keep trying, sooner or later you'll start to get the hang of the expression language.
Although I am tempted to write the 1st CRM expressions book as it couldn't hurt since there is really nothing else available unless you want to pay the $5K to go through the advanced reporting class. The only reason I haven't gone to that is I suspect nobody over there knows how to really use the language either, otherwise they'd have better documentation.
Let me know if you have any specific questions, maybe I can help.
Dan DeHaven (Desperately Trying to Learn)

Similar Messages

Help needed in JSP Expression Language

Hi all,
I have been working for JSP Expression Language Sample execution since past 5 days. I am using the application server as "Jboss Server" and web server as "Tomcat".
I have been included the jsp-api.jar file in my lib directory of application server as well as source folder's lib directory.
When i am trying to build the source code, i am getting this build error.
[javac] D:\eclipse\workspace\esolvProject\development\src\com\esolv\taglibs\
web\classes\SetSupport.java:186: cannot resolve symbol
[javac] symbol : method getExpressionEvaluator ()
[javac] location: class javax.servlet.jsp.PageContext
[javac] ExpressionEvaluator evaluator = pageContext.getExpressionEvaluator();
In my jsp-api.jar , there are two classes called,
PageContext and JspContext, Both are abstract classes.
PageContext inherits JspContext class. JspContext class have the method getExpressionEvaluator() , returns ExpressionEvaluator.
PageContextImpl - class . it has been called internally when we are trying to call PageContext class. In PageContextImpl class, there is one comment before, the method's definition. that is
" Since JSP 2.0 "
But we have the JSP 2.0 version. But it won't work.
Please help me ont this.
Thanks in Advance,
Natraj

>
If the pblm was due to setting the classpath.
The error should be showed for all files in the jar
file.
why i am getting the error for particular method ?
it is accessing the other methods of same class
'JspContext' . but it is not accessing that method.
Thats my question.
Just check that your .jar file is 2.0 compliant and that you do not have any other jars(for servlet or jsp api) in the classpath.
Probably you have an older version of .jar file in your path. So the errors will appear only for those methods that have been added since 2.0, all other methods would compile fine.
Please tell me the jar files to work out the
expression language. so that i can cross check my
list of jars.Hmmm...I dont use jboss. In tomcat the jar file name is jsp-api.jar. But it would have been the same even for jsp1.1, going by jar file names wouldnt help. Just look at your cp as if with a microscope to identify redundant jars.
cheers,
ram.

Need Help on Express Language

Can Anybody please help me out how express language works and if possible with examples.
Thanks for your help.
Gajendra Nagapurkar
[email protected]

the reference guide has a full tutorial on the language. if you know xml and any programming language, you should have no trouble learning it.
Dana Reed
AegisUSA
Denver, Co
773.412.3782

Help me!!!. Please help me fix bug Expression Language Injection in Portal

hi all,
I'm trying to fix bug Expression Language Injection vulnerabilities on oracleas portal, error scanning tool using Acunetix Web Vulnerability Scanner ver 8.0 build 20120209
I tried to include in the portlet filters special characters to detect signs of attack websites. For example an attack details: URL encoded GET input product_id was set to ${99240+11490}
But the way I tried above fails, scan tools Acunetix identified a bug that is high
I hope to soon get the help :)
I thank very much
Jackie
E: [email protected]

hello Erik Janssen,
Thank you very much. I've tried it that way but when scanned by Acunetix Web Vulnerability Scanner tool ver 8.0 still errors appear Expression Language Injection.
I describe to you more clearly understand. For example an attack details:
URL encoded GET input product_id was set to *${99240+11490}*
* Request
GET /portal/page/portal/listpro?product_id=%24%7b99240+11490%7d
I built a special filter characters in the portlets so that if the value retrieved from the parameter contains special characters are predefined Raise Error, but still not successful bug fix.
Look forward to receiving your help. Thank you very much :)
Jackie
E: [email protected]

{Expression Language} not working tomcat5 j2se 1.5_beta

I m new to JSP technology. I m trying to use expression language in my application and it's not letting me do the job.
simple program
<head> <body>
Hi there! 3 + 3 is ${3+3}
</body></head>
It just shows " Hi there! 3 + 3 is ${3+3} " as the output. I tried google search. it seems the problem is across many networks like in bea weblogic etc.,
when i used <%@page isELEnabled="true" > i get an error saying attribute isELEnabled not recognised or something like that. My web.xml hasn't got any setting for jsp so I don't know where the "*.jsp" section is available, just in case that needs any touchup.
I have installed JSTL under /common/lib dir. but i think this library is not required for using basic EL.
So, can anyone help me configure my JSP page so that i can use EL tags in them.
OS: Windows 2000
Tomcat ver: 5
J2Se: 1.5 beta

Hmmm. Looks like I didn't make myself clear enough.
You still have the declaration DTD for servlet 2.3 at the top of your web.xml.
To enable EL using Tomcat 5 you only need to do ONE of the following:
1 - update your web.xml file to have the header for the 2.4 version (note its not a DTD anymore)
2 - if your web.xml uses the DTD from version 2.3, include the page directive <%@ page isELIgnored="false" %> on any pages
Basically the rules for executing EL are as follows:
1 - Is there a directive on the page? If yes, then enable/disable according to the directive.
2 - Is there an entry in web.xml for handling EL? If yes then enable/disable according to the setting
3 - Is the web.xml file for the Servlet 2.4 spec? (ie does it start have the version 2.4 header) Yes = enable EL No = disable EL
The easiest way of enabling EL is updating your web.xml to be compliant with the latest servlet spec.
Cheers,
evnafets

JDeveloper ADF Faces Problem: Expression language

Error(): Expression Language not supported in compile time attribute test
I have followed an ADF Faces example from the Oracle Website. Concerning a database + ADF Faces
http://www.oracle.com/technology/pub/articles/cioroianu_jsfadf_v4.html
I followed the tutorial correct but everytime i try to run it. I get following error:
Error(): Expression Language not supported in compile time attribute test
It has something to do with following line of code
<c:if test="${subscriber == null || !subscriber.loggedIn}">
The error appears on every page where "<c:" appears.
I have imported the right class library
<%@ taglib prefix="c" uri="http://java.sun.com/jstl/core" %>
Does anybody have any idea what i can do?

Dear Tim,
What a chance!!! I've got the same problem as you?!
I've tried almost everything, but still haven't succeeded to solve it!
Hopefully someone can help us.
Greetings

Unified Expression language framework in another context than JSP/JSF

Hi
+(I hope this is the right place for such question)+
We are building some RCP apps and we are in need, for our frameworks, of a expression language that allows to get and set values, and other things, and it seems that the Unified Expression Language Framework meets our need.
However, as I said, this is a RCP app, not a web app. So my question is
Is this framework designed to be used outside of the web app context (jsp, jsf, etc) ? Or is there any dependencies that would prevent or make it difficult to use it in a GUI RCP application?
Thanks for your help
cd

BalusC wrote:
It's so cool that you can change the way to read your sentence. I never read it any other way. I probably shouldn't have posted a double meaning statement but saying that I'm changing the way I read it is incorrect. I'm not doing that.
BalusC wrote:
It's also a great coincidence that you mention exactly the references which are implicitly available in the scriptlet world.Not sure what that's intended to mean. I was exposing to the OP the part of EL that deals with objects that require/assume a j2ee container.

Text/expression-language-based paradigma continues?

i've been working with jsp and struts for a while. the most significant drawback of jsp, custom tags/jstl and struts is its "runtime" binding caused by the heavy use of string-attributes and interpreted expressions.
it makes the coding itself harder (loss of compiler support and strong typing), it increases the amount of testing (automated tests, regression tests) extremely, it makes jsp-apps very hard to mantain, it is error-prone when changed or refactored, it is slower in execution and last but not james requires extra developement tools (such as struts-editors) to effectively maintain the applications.
but i like the paradigma of a web application that keeps a view state, handles "events" etc.
the only thing i can't understand is why jsf builds on the error-prone jsp/custom tag paradigma instead of compiled server side ui components. it obviuosly still tries to follow the myth, that web-designers and application developers can share their source (i.e. js-pages) by using tags. imo this is a degeneration of the good idea to leverage html by some custom tags. these tags empower designers to make their pages dynamic. (enterprise) software developement ist very different: complex use cases, business logic and often ui-"logic", integration issues etc...
the life cycle of a jsp with custom tags is weird (even more in struts):
- objects (variables in scriptlets) already existing in the scope of the jsp-execute-method are wrapped into attributes of page, request or application scope.
- tags are defined using string-based attributs, such as <html:write name="pinky" property="brain" />
- the implementation of the tag tries to look up the object in any of the scopes, starting with page scope
- if the object exists, it tries to read/set its property via reflection
so you lose strong typing, compile time checks and performance.
there are several frameworks that do not build upon jsp and tags but put in an extra layer. this layer is similar to a rich client "form" and renders the output into html or any other format.
so i'm not preferring any framework, just looking around and curious why this architecture has been chosen for jsf.
thanks
tom

the most significant drawback of jsp, custom tags/jstl and struts is its "runtime" binding
caused by the heavy use of string-attributes and interpreted expressions.I second this heartily.
but i like the paradigma of a web application that keeps a view state, handles "events" etc.
the only thing i can't understand is why jsf builds on the error-prone jsp/custom tag
paradigma instead of compiled server side ui components. The JSF - JSP connection is a major problem. More and more developers are starting to express reservations about it, because the two technologies don't play well together. But I think you've hit on an even deeper fundamental flaw in the equation -- the evils of runtime binding. The heavy JSF/JSP reliance on runtime evaluation is a reliability nightmare. Developers choose Java, in part, because of the robustness provided by compile-time checking. We give that up when it comes to JSF/JSP or Struts web applications, and that's an unacceptable state of affairs.
Winer says that "JSF has taken a major step in the right direction with the <managed-bean> and <referenced-bean> configuration elements. These give some hope for development tools to finally provide real code insight (and even error reporting) for EL expressions, because they define both what keys are used in the expression language and what types of objects may be at those keys." However, this will help with only the simplest EL expressions. As soon as an EL expression reaches into nested properties and maps that aren't defined in the config file, we're back to runtime binding and error reporting. The addition of generics to the language with 1.5 might have made it possible to introduce strong EL type checking at page compile time, but Sun's short-sighted type-erasure implementation of generics rules this out permanently.
Look at what Microsoft is doing with ASP.NET. It's not perfect, but the fundamental technology is based on compiled server side ui components. There are places in that framework where you can write expressions aren't evaluated until runtime, but it's certainly not the fundamental basis of the model as it is with JSF/JSP. And the .NET implementation of generics may make it possible to have these dynamic expressions type-checked at page compile time in a future implementation of .NET.
I keep reading comments from the JSF proponents who say things to the effect of "yes, we know JSP doesn't play well with JSF, but JSF allows you to plug in a different rendering technology." Well, we need one, and we need it urgently. ASP.NET has been out for two years now, and was far more polished and useable at its release than JSF is now after a very long development cycle.
Rightly or wrongly, people will judge JSF on the merits of the reference implementation. And I fear that a lot of developers are going to throw up their hands after a taste of the JSF/JSP world and move to .NET.
Stephen Schaub

Expression language

Hi,
I need some help on clarifying the expression language. I have this code
<h:outputText value="variable"/>I want to replace the variable with a value from the database. How can I do this using the expression language? Or do I need to use the JSP scriplet and call a bean function?
clarenceloh

Basically:<h:outputText value="#{myBean.variable}" />MyBeanprivate String variable; // + getter + setter
loadVariable(); // Can also use constructor or static block for this.
private void loadVariable() {
variable = getVariableFromDatabaseSomehow();
}

How to use constant in expression language

I have class Constant which contains
public static final (constant fields).
I want to use those constants in expression language in jsp
${requestScope.result eq with some constant}
<c:if test="${requestScope.result eq '<%= Constants.MODE %>'}">
Hello World
</c:if>
It does not print Hello World
even though MODE is 'hello' and result is also set to 'hello'.
Message was edited by:
mihir_kapadia

Its not that simple. There is an article in [url http://www.javaranch.com/journal/200601/Journal200601.jsp#a3]javaranch about the usage of constants in EL.
There is [url http://forum.java.sun.com/thread.jspa?forumID=45&threadID=508847]this cool code snippet from forum user evnafets that would help you with your problem.
ram.

Support for JSTL Expression Language?

Is JSF going to support Expression Language ?

Hi mayssam,
In this thread
http://forum.java.sun.com/thread.jsp?forum=427&thread=413603
There was a long discussion on how to make it work. I think I remember somewhere Craig posting that it was going to work but you should search the archives of this list for more info on it. If I remember correctly there were a few issues with using the EL and the expert group did not want to require JSP 2.0 or something like that.
Anyway your answer is somwhere in the archives.
hope this helps,
-bd-
http://bill.dudney.net/roller/page/bill

UIX Arrays in Expression Language

Hi All,
Does anybody know if it is possible to have an array in expressionlanguage?
How for example can you specify a four object array like:
{objectA, objectB, objectC, objectD}Is this possible in expression language and if yes how?
I want to use this for my own EL function, I have specified, that I want to use in a UIX page.
Thanks for any help,
Gideon

Hello,
This is not supported. We'd like to support it, but JSTL doesn't support it yet. I found this thread on the web that you might find interesting.
http://mail-archives.eu.apache.org/mod_mbox/jakarta-taglibs-user/200406.mbox/%[email protected]%3E
Jeanne

Expression language oa.current.FieldName meaning?

I've seen this in existing codes property inspector window
${oa.current.FieldName}.The syntax closely resembles that of jstl
I only know the format to display the attribute of the current row of the given VO:
${oa.SomeNameVO1.voAttribute}What does oa.current mean?
Where can I get more information about the different objects available in this expression language?
Help is much appreciated.

Hi,
Refer PPR and Tables of the developer guide.
You can also fire row-level PPR events for items in a table, including advanced tables and table-in-table. First and foremost, configure the items as described above.
Note: If you are working with a table-in-table or HGrid that uses view links, you need to modify your SPEL syntax as shown: ${oa.current.viewAttrName}. The inclusion of current keyword lets you say "get the value from whatever row BC4J is using to render the current row" since you won't know how to access the view
objects and row sets created dynamically for these complex components.Regards,
Gyan

Problem in accessing object using Expression Language

Hello All,
Im using Tomcat 5.5 and I am learning Expression language.Im using one servlet page as login.java i.e,
package common;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
import javax.servlet.RequestDispatcher;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import Database.DatabaseObject;
import valueobjects.login1;
public class login extends HttpServlet {
     public static final long serialVersionUID = 8707690322213556804l;
     public void doPost(HttpServletRequest req, HttpServletResponse res) {
          String name = req.getParameter("username");
          String password = req.getParameter("password");
          RequestDispatcher dispatch = null;
          ResultSet rs=null;
          Statement st=null;
          login1 log=null;
          Connection con = null;
          String sql=null;
          try
          con=new DatabaseObject().getConnection();
          st = con.createStatement();
          sql="select * from login";
          System.out.println(sql);
          rs=st.executeQuery(sql);
          while(rs.next())
               log=new login1(rs.getString("User_Name"),rs.getString("user_Password"));
          req.setAttribute("login",log);
          req.setAttribute("username",name);
          req.setAttribute("password",password);
          dispatch = req.getRequestDispatcher("/jsps/el.jsp");
          dispatch.forward(req, res);
          catch(Exception e)
               e.printStackTrace();
That login1 customized object is set as ,
package valueobjects;
public class login1{
     String Name;
     String Password;
     public login1(String name, String password) {
          super();
          // TODO Auto-generated constructor stub
          Name = name;
          Password = password;
     public String getName() {
          return Name;
     public void setName(String name) {
          this.Name = name;
     public String getPassword() {
          return Password;
     public void setPassword(String password) {
          this.Password = password;
then im using one jsp as el.jsp that is,
<%@ page isELIgnored="false"%>
<%@ page import = "java.util.*,valueobject.*"%>
<html>
<jsp:useBean id="login" class="valueobjects.login1">
<jsp:setProperty name="login" property="name" value="username"/>
<jsp:setProperty name="login" property="password" value="password"/>
</jsp:useBean>
<body>
     <center>
     username=${login.Name}<br><br>
     </center>
</body>
</html>
but when i execute this code it is giving error as
/jsps/el.jsp(4,0) The value for the useBean class attribute valueobjects.login1 is invalid.
But that login1.java is in correct package that is valueobjects.but im not getting why it is giving such error.Plz help me.

hi
to use java bean u MUST follow the two conviosions:
1. the class u want to make a bean from it must have no-argument constructor
2. u must provide setter and getter for every instance variable , the name of instance varible must begin with small letter and its setter and getter must be like setXxx() and getXxx()
the correct bean is :
package valueobjects;
     public class login1{
     String name;
     String password;
     public String getName()
               return name;
     public void setName(String name)
               this.name = name;
     public String getPassword()
                return password;
     public void setPassword(String password)
                this.password = password;
     }where is my duke's $ ???

Simple question - compare Strings with SSIS expression language

SSIS variables - strOne = YES, strTwo = YES. I want to compare strings using ssis expression language (ie inside a variable's expression box, constraint of task flow arrow etc).
Will @strOne == @strTwo be true ? I hope its not like programming languages where you need to do
@strOne.Equals(@strTwo) instead of ==. Also is @strOne == "YES" true ?

([User::strOne] == [User::Strtwo] ? True : False)
The third variable created should be of type boolean if you're using above expression. if its of type int return 0 and 1 instead of False and true
Please Mark This As Answer if it helps to solve the issue Visakh ---------------------------- http://visakhm.blogspot.com/ https://www.facebook.com/VmBlogs

Expression Language - Help

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