I have, what I believe, is an extremely simple problem, yet all of my attempts to resolve it have failed.
In a nutshell:
I have a JSP file with a form that invokes a Java Servlet.
The servlet processes the input and returns a variable (attribute) and redirects back to the same jsp.
I want to the jsp to process the returned attribute using JavaScript, NOT a scriptlet.
JSP Code (test.jsp):
<html>
...
<%#page language="java"
import="java.sql.*"
import="java.util.*"
%>
...
<body>
<script type='text/javascript'>
var name = session.getAttribute("test");
alert(name);
</script>
...
</body>
</html>
And the Servlet code:
protected void doPost(HttpServletRequest request, HttpServletResponse response) {
request.getSession().setAttribute("test", "value");
String redirectedPage = "/test.jsp";
RequestDispatcher reqDispatcher = getServletConfig().getServletContext().getRequestDispatcher(redirectedPage);
reqDispatcher.forward(request,response);
}
I believe that the problem stems from my declaration of the session variable:
var name = session.getAttribute("test");
I have also tried:
var name = (String) session.getAttribute("bob");
and:
String name = (String) session.getAttribute("bob");
I can access this attribute from within my form using a scriptlet (<% %>), but that doesn't allow me to modify/process the returned attribute, which I need to do.
Any help is greatly appreciated. If you feel this question has already been asked/addressed (I've searched), please POLITELY let me know.
You can not access the session from javascript, but you can of course create your javascript on the server side.
<script type='text/javascript'>
var name = '<%= session.getAttribute("test") %>';
alert(name);
</script>
If you don't have 100% control of the actual value (and maybe even then) it's is a good idea to escape the string. Otherwise someone might inject values that breaks your page (best case) or enables some XSS to steal user data or hijack user session.
Using Apache commons StringEscapeUtils (JavaDoc) It would look like this
<script type='text/javascript'>
var name = '<%= StringEscapeUtils.EscapeJavaScript((String)session.getAttribute("test")) %>';
alert(name);
</script>
If you are going to use this a lot (or maybe just even once) I'd recommend creating a tag that takes the attribute name and outputs a javascript safe string. Maybe as <MyJsTags:AttributeAsString name="test"/> to avoid script lets in your JSP and it also makes it easier if you want to impose new functionality when accessing the attribute.
Related
While trying to iterate a map in a javascript function by passing key as below:
<html> <head>
<script type="text/javascript">
function demo(tmp){
<c:forEach var="user" items="${usermap}">
<c:out value="${usermap.get(\"+'tmp'+\").name}"></c:out>
</c:forEach>
}
</script>
<title>Insert title here</title> </head>
<body>
<h1 onclick="demo('user1')">User VO</h1>
<c:forEach var="user" items="${usermap}">
Key: ${user.key} - Name: ${user.value.name} - Id: ${user.value.userid}<br/><br/>
</c:forEach>
</body> </html>
I am getting blank value. But when I hard code the value of key***user1***, it works.
Servlet Code
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
//System.out.println("in servlet doGet:"+ ++count);
UserVO user1= new UserVO("Y","701");
UserVO user2= new UserVO("D","834");
hmap.put("user1", user1);
hmap.put("user2", user2);
//hmap.values()
request.setAttribute("usermap", hmap);
//response.sendRedirect("User.jsp");
RequestDispatcher view = request.getRequestDispatcher("User.jsp");
view.forward(request, response);
//response.getWriter().append("Served at: ").append(request.getContextPath());
}
Can somebody help me here?
The Issue:
You are mixing client side and server side code. JavaScript and JavaServer Pages are executed separately.
JSP code is compiled on the server,
The result is a HTML, that is delivered to the browser
In the browser the JavaScript is executed
So JSP related stuff like:
JSTL, JSP Standard Tag Library (tags like <jsp:something> <c:something>)
JSP-EL, Expression Language (strings like ${something})
is processed on the server.
You can see, what HTML code is received in browser, by pressing Ctrl+U in Firefox/Chrome.
In your case:
Selecting an option in the select-tag is executed on the client side in browser.
It is too late for EL-evaluation. The EL has bean already evaluated.
You can use ajax to request the needed data (map) according the user selection.
EDIT:
The EL of the hardcoded line is executed on the server and replaced with the value. On the other case, when select-tag is involved, the EL was executed on the server and replaced by var Cfs_id ="";. So the dummy function ignore the parameter serviceId and set the variable always to empty string.
Look the code in your browser. There is only Html and Javascript. The JSP EL are no more there.
In my application when the user is login the particular user id is stored in the session. I want to get this id in a js file.In this js file contain state provider,factory etc
js
var sessionValue = "'"+<%=Session["userId"]%>+"'"
alert(sessionValue)
But it is show some error(Unexpected)
1.You can assign session value to hidden field.
<input type="hidden" name="userId" id="userId" value="<%= Session["userId"] %>">
Get hidden field value from javascript function.
function GetUserId()
{
var userId = document.getElementById('userId').value;
alert(userId);
}
You can use something like
<script type="text/javascript">
function GetUserId()
{
var userId = '<%= Session["userId"] %>';
alert(userId);
}
</script>
I think that the problem is that your webserver isn't evaluating as ASP .js files. You have three different way to get what you want
configure your webserver so that .js files are treated as ASP pages,
but noone would ever do that, it would add overhead over your
code.
Render your js starting from a .asp page placing in your html
something like: < script src="mysite/getjavascript.asp" >
Load session values with an ajax calls
Remember to print proper headers before printing your javascript
I use this for different languages on our site:
Locale locale2 = (Locale)session.getAttribute("org.apache.struts.action.LOCALE");
ResourceBundle bundle = ResourceBundle.getBundle("content.test.Language", locale2);
I can easy access the string values of the ResourceBundle in HTML to include it on the site via:
<%= bundle.getString("line1") %>
But in some cases I need to access the string values out of javascript.
I have not found a way to do this so far.
I only found a ugly workaround to get the string values.
On the HTML part I include:
<input type="hidden" name="hiddenLine2" id="hiddenLine2" value=<%= bundle.getString("line2") %>>
I do this for all strings I could possibly need.
To access one of them out of javascript I do this:
var line2 = document.getElementById("hiddenLine2").value;
This is working so far, but I don´t like it.
I am sure there could be a better solution.
Some of the possible solutions.
Use an ajax method to get your resource by passing a key.
Use Hidden input fields and load values.
Use a dedicated jsp page to declare js variables or even a js function to get values according to key.
like this.
<script type="text/javascript">
var messageOne = '<%=bundle.getString("line1") %>';
var messageTwo = '<%=bundle.getString("line2") %>';
</script>
It is normally bad practice to use scriplets <% %> inside your jsp files.
You can use the fmt tag from the jstl core library to fetch information from your resource bundles.
<fmt:bundle basename="bundle">
<fmt:message var="variableName" key="bundleKey" />
</fmt:bundle>
<input type="hidden" name="hiddenLine2" id="hiddenLine2" value="${variableName}">
should work
infact, i think you can also directly embed it into the javascript with EL aswell
var line2 = ${variableName}; //instead of getting it from document.getElement(...)
Based on what I have tried, you can use jstl library to print the translated messages directly into JavaScript like:
alert("<fmt:message key='line1'/>");
And if you are using struts2 for handling the locales you can easily define you Bundles getting either the struts2 locale, saved by the i18nInterceptor present on the default stack, or the user request locale (the clients' browser one)
<!-- //Import the requierd libraries -->
<%#taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<%#taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!-- //Take the Locale from struts if it's present and from the user request if not -->
<c:set var="locale" value="${not empty sessionScope.WW_TRANS_I18N_LOCALE
? sessionScope.WW_TRANS_I18N_LOCALE : pageContext.request.locale}"/>
<!-- //Get the bundle based on the Locale -->
<fmt:setLocale value="${locale}"/>
<fmt:setBundle basename="content.test.Language"/>
But if you want to be able to extract that JavaScript code into an external .js file on the future I recommend you to use some of the internalionalization libraries available for JavaScript, like Globalize (It's the only one I have used, but there are plenty on the net).
The downside of using an external JavaScript library for internationalization is that you will have to define the tranlation resources directly on .js files, it's impossible to access to your .properties on the server from a client-based language like JavaScript.
Here is a different solution.
Load bundle like OP did, with the method getBundle().
Using the third option on Arun's answer, create a separate JSP file to create a custom JavaScript object.
This is the content of said JSP:
<%#page import="com.tenea.intranet.conf.Conf" %>
<%#page import="java.util.ResourceBundle,
java.util.Enumeration" %>
<script type="text/javascript">
var _get = function(ID){
if (this.hasOwnProperty(ID)) return this[ID];
else {
console.warn("[Resources] Error al obtener clave <"+ ID +">");
return "[ERROR]";
}
};
var _search = function(text){
var elems = { }
Object.keys(this).map(e => {
if (typeof (this[e]) !== "function" && this[e].includes(text)) { elems[e] = this[e]; }
});
return elems;
};
var Resources = {
<%
ResourceBundle labels = ResourceBundle.getBundle("content.test.Language", locale2);
Enumeration<String> e = labels.getKeys();
while (e.hasMoreElements()) {
String param = e.nextElement();
out.print(param +":\""+ labels.getString(param) +"\"");
if (e.hasMoreElements()) out.println(",");
}
%>
};
Resources._get = _get;
Resources._search = _search;
</script>
What this JSP does is:
Creates object Resources
Using some snippets (sorry Martin :p), and iterating on the list of keys from the resourceBundle, for each key I print a line like "key: value" with out.println().
The resulting object is something like this:
Resources {
abrilAbrText: "Apr"
abrilText: "April"
...
}
To make some extra functionality, I also added 2 functions inside Resources.
_get() returns the text related to the key passed as parameter. If said key doesn't exist, return the text '[ERROR]'.
_search() is a function I added for development purposes. It searches and returns a custom object with every key whose corresponding text contains the text passed as parameter. NOTE: since it uses "e => {}", it won't work on IE or Safari, so it's best to comment it once the development phase has ended.
Once you have this JSP created, to use it you just have to import it to any JSP you want with this:
<%#include file="[relative_path]" %>
Hope it helps! :)
How to set the JSTL variable value in java script?
<script>
function function1()
{
var val1 = document.getElementById('userName').value;
<c:set var="user" value=""/> // how do i set val1 here?
}
</script>
How do I set the 'user' variable (JSTL) value from 'val1' (Java script)?
It is not possible because they are executed in different environments (JSP at server side, JavaScript at client side). So they are not executed in the sequence you see in your code.
var val1 = document.getElementById('userName').value;
<c:set var="user" value=""/> // how do i set val1 here?
Here JSTL code is executed at server side and the server sees the JavaScript/Html codes as simple texts. The generated contents from JSTL code (if any) will be rendered in the resulting HTML along with your other JavaScript/HTML codes. Now the browser renders HTML along with executing the Javascript codes. Now remember there is no JSTL code available for the browser.
Now for example,
<script type="text/javascript">
<c:set var="message" value="Hello"/>
var message = '<c:out value="${message}"/>';
</script>
Now for the browser, this content is rendered,
<script type="text/javascript">
var message = 'Hello';
</script>
Hope this helps.
one more approach to use.
first, define the following somewhere on the page:
<div id="valueHolderId">${someValue}</div>
then in JS, just do something similar to
var someValue = $('#valueHolderId').html();
it works great for the cases when all scripts are inside .js files and obviously there is no jstl available
<script ...
function(){
var someJsVar = "<c:out value='${someJstLVarFromBackend}'/>";
}
</script>
This works even if you dont have a hidden/non-hidden input field set somewhere in the jsp.
Just don't. Don't write code with code. Write a JSON object or a var somewhere but for the love of a sensible HTTP divide, don't write JavaScript functions or methods hardcoded with vars/properties provided by JSTL. Generating JSON is cool. It ends there or your UI dev hates you.
Imagine if you had to dig into JavaScript to find something that was setting parameters in the middle of a class that originated on the client-side. It's awful. Pass data back and forth. Handle the data. But don't try to generate actual code.
You have to use the normal string concatenation but you have to make sure the value is a Valid XML string, you will find a good practice to write XML in this source http://oreilly.com/pub/h/2127, or if you like you can use an API in javascript to write XML as helma for example.
This variable can be set using value="${val1}" inside c:set if you have used jquery in your system.
As an answer I say No. You can only get values from jstl to javascript. But u can display the user name using javascript itself.
Best ways are here.
To display user name,
if u have html like
<div id="uName"></div>
You can display user name as follows.
var val1 = document.getElementById('userName').value;
document.getElementById('uName').innerHTML = val1;
To get data from jstl to your javascript :
var userName = '<c:out value="${user}"/>';
here ${user} is the data you get as response(from backend).
Asigning number/array length
var arrayLength = <c:out value="${details.size()}"/>;
Advanced
function advanced(){
var values = new Array();
<c:if test="${empty details.users}">
values.push("No user found");
</c:if>
<c:if test="${!empty details.users}">
<c:forEach var="user" items="${details.users}" varStatus="stat">
values.push("${user.name}");
</c:forEach>
</:c:if>
alert("values[0] "+values[0]);
});
You can save the whole jstl object as a Javascript object by converting the whole object to json. It is possible by Jackson in java.
import com.fasterxml.jackson.databind.ObjectMapper;
public class JsonUtil{
public static String toJsonString(Object obj){
ObjectMapper objectMapper = ...; // jackson object mapper
return objectMapper.writeValueAsString(obj);
}
}
/WEB-INF/tags/util-functions.tld:
<?xml version="1.0" encoding="ISO-8859-1" ?>
<taglib xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd"
version="2.1">
<tlib-version>1.0</tlib-version>
<uri>http://www.your.url/util-functions</uri>
<function>
<name>toJsonString</name>
<function-class>your.package.JsonUtil</function-class>
<function-signature>java.lang.String toJsonString(java.lang.Object)</function-signature>
</function>
</taglib>
web.xml
<jsp-config>
<tablib>
<taglib-uri>http://www.your.url/util-functions</taglib-uri>
<taglib-location>/WEB-INF/tags/util-functions.tld</taglib-location>
</taglib>
</jsp-confi>
mypage.jsp:
<%# taglib prefix="uf" uri="http://www.your.url/util-functions" %>
<script>
var myJavaScriptObject = JSON.parse('${uf:toJsonString(myJstlObject)}');
</script>
How to set the JSTL variable value in java script?
<script>
function function1()
{
var val1 = document.getElementById('userName').value;
<c:set var="user" value=""/> // how do i set val1 here?
}
</script>
How do I set the 'user' variable (JSTL) value from 'val1' (Java script)?
It is not possible because they are executed in different environments (JSP at server side, JavaScript at client side). So they are not executed in the sequence you see in your code.
var val1 = document.getElementById('userName').value;
<c:set var="user" value=""/> // how do i set val1 here?
Here JSTL code is executed at server side and the server sees the JavaScript/Html codes as simple texts. The generated contents from JSTL code (if any) will be rendered in the resulting HTML along with your other JavaScript/HTML codes. Now the browser renders HTML along with executing the Javascript codes. Now remember there is no JSTL code available for the browser.
Now for example,
<script type="text/javascript">
<c:set var="message" value="Hello"/>
var message = '<c:out value="${message}"/>';
</script>
Now for the browser, this content is rendered,
<script type="text/javascript">
var message = 'Hello';
</script>
Hope this helps.
one more approach to use.
first, define the following somewhere on the page:
<div id="valueHolderId">${someValue}</div>
then in JS, just do something similar to
var someValue = $('#valueHolderId').html();
it works great for the cases when all scripts are inside .js files and obviously there is no jstl available
<script ...
function(){
var someJsVar = "<c:out value='${someJstLVarFromBackend}'/>";
}
</script>
This works even if you dont have a hidden/non-hidden input field set somewhere in the jsp.
Just don't. Don't write code with code. Write a JSON object or a var somewhere but for the love of a sensible HTTP divide, don't write JavaScript functions or methods hardcoded with vars/properties provided by JSTL. Generating JSON is cool. It ends there or your UI dev hates you.
Imagine if you had to dig into JavaScript to find something that was setting parameters in the middle of a class that originated on the client-side. It's awful. Pass data back and forth. Handle the data. But don't try to generate actual code.
You have to use the normal string concatenation but you have to make sure the value is a Valid XML string, you will find a good practice to write XML in this source http://oreilly.com/pub/h/2127, or if you like you can use an API in javascript to write XML as helma for example.
This variable can be set using value="${val1}" inside c:set if you have used jquery in your system.
As an answer I say No. You can only get values from jstl to javascript. But u can display the user name using javascript itself.
Best ways are here.
To display user name,
if u have html like
<div id="uName"></div>
You can display user name as follows.
var val1 = document.getElementById('userName').value;
document.getElementById('uName').innerHTML = val1;
To get data from jstl to your javascript :
var userName = '<c:out value="${user}"/>';
here ${user} is the data you get as response(from backend).
Asigning number/array length
var arrayLength = <c:out value="${details.size()}"/>;
Advanced
function advanced(){
var values = new Array();
<c:if test="${empty details.users}">
values.push("No user found");
</c:if>
<c:if test="${!empty details.users}">
<c:forEach var="user" items="${details.users}" varStatus="stat">
values.push("${user.name}");
</c:forEach>
</:c:if>
alert("values[0] "+values[0]);
});
You can save the whole jstl object as a Javascript object by converting the whole object to json. It is possible by Jackson in java.
import com.fasterxml.jackson.databind.ObjectMapper;
public class JsonUtil{
public static String toJsonString(Object obj){
ObjectMapper objectMapper = ...; // jackson object mapper
return objectMapper.writeValueAsString(obj);
}
}
/WEB-INF/tags/util-functions.tld:
<?xml version="1.0" encoding="ISO-8859-1" ?>
<taglib xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd"
version="2.1">
<tlib-version>1.0</tlib-version>
<uri>http://www.your.url/util-functions</uri>
<function>
<name>toJsonString</name>
<function-class>your.package.JsonUtil</function-class>
<function-signature>java.lang.String toJsonString(java.lang.Object)</function-signature>
</function>
</taglib>
web.xml
<jsp-config>
<tablib>
<taglib-uri>http://www.your.url/util-functions</taglib-uri>
<taglib-location>/WEB-INF/tags/util-functions.tld</taglib-location>
</taglib>
</jsp-confi>
mypage.jsp:
<%# taglib prefix="uf" uri="http://www.your.url/util-functions" %>
<script>
var myJavaScriptObject = JSON.parse('${uf:toJsonString(myJstlObject)}');
</script>