Can I preserve object across actions in Struts2 without using session?
I'm working on a Struts2 project and curious if there are some ways to preserving object
value once an action is ended.
What I'm trying to do is:
Calling an action to read from an uploaded file and prepare its contents as a list of objects.
Then I display the list as an example for the user.
Then the user can click on a submit button to call an action to process the list which is created from the first action.
Usually the list would be lost once the action is end. So, I have to store the list as a session, but I think it should have some better methods to achieve the I'm working on.
If you want to preserve data across requests the session is the normal mechanism for doing so.
If you don't use the session you'd need to essentially duplicate its functionality to maintain the data associated with the current user/conversation.
If you need to preserve the List, then you have to use the Session.
But if you (if I've understood your problem) just need to handle the List through
ActionOne (that creates the List) ->
JSPOne (thast shows the List to the user) ->
ACtionTwo (that receives the List from JSPOne and does some business with it)
, without having to worry about the fact that the user can change the List client-side (for example manipulating the web page with FireBug), then you don't need the session.
You just need the List object to be declared on ActionOne and ActionTwo (with getters and setters, at least the getter on ActionOne and at least the setter on ActionTwo), and to include List name and index on name attribute of JSP tags.
If you just draw it (like with <s:property/> tag), instad of using some tag that will post the value, like <s:textfield />, then just use an <s:hidden /> to post te value.
For example, if you have:
List<MyObject> myList //with getters and setters
and assuming that MyObject has id and value fields (with getters and setters),
in JSP instead of
<s:iterator value="myList" >
<s:property value="id"/>
<s:textfield name="value"/>
</s:iterator>
use
<s:iterator value="myList" status="ctr" >
<s:hidden name="myList[#ctr.index].id" value="id"/>
<s:property value="id"/> <!-- no need here, you won't post this -->
<s:textfield name="myList[#ctr.index].value" value="value" />
</s:iterator>
You will eventually validate a List like this throught the Visitor Validator (somewhewre in the future after all the rest is done :)
Enjoy
Related
I need to iterate through List<String>, each element has s:checkbox.
I have defined one list in Action layer to keep selected elements.
Using my code I can submit my form and capture selected values in action layer. But, some of the checkboxes must be pre-checked. I cannot display pre- checked status when loading the page.
Value1 contains list of String objects.
functionCheckBoxList - The list I have defined to keep checked element
While loading, I added some element to functionCheckBoxList that belongs to Value1.
But still does not show pre-checked status in the page.
<s:iterator value="value1" var ="functionName">
<s:checkbox fieldValue="%{#functionName}" name="functionCheckBoxList"
value="%{#functionName}" theme="simple" >
</s:checkbox>
</s:iterator>
Note: I know how to do it using s:checkboxlist but can't here as I need special format in the iteration.
i could find a solution for my problem, i would like to share it with everyone.
<s:iterator value="value1" var ="functionName">
<s:checkbox fieldValue="%{#functionName}" name="functionCheckBoxList"
value="%{#functionName in functionCheckBoxList}" theme="simple" >
</s:checkbox>
</s:iterator>
I have a JSP page where am printing the arraylist content via an iterator
<s:iterator var="BeanList" value="BeanList">
<option value='<s:property value="#BeanList.simpleID"/>'>
<s:property value="#BeanList.simpleText" />
</option>
</s:iterator>
Every time the user selects an option, the form submits to the action handling. I want to be able to take the value of the clicked option, and when the page is reloaded after the submit, the same value persists in the select drop down.
Any help will be greatly apprecaited,
You are using HTML Select Tag, with values populated from Struts2 Property Tag.
No JSTL is involved.
But believe me, you can avoid this using the Struts2 Select Tag directly.
Official documentation: http://struts.apache.org/release/2.3.x/docs/select.html
In Action
#Getter #Setter List<String> allCities;
#Getter #Setter String selectedCity;
In JSP:
<s:select list="allCities"
name="selectedCity" />
Faster and cleaner than iterating manually :)
Eventually you can add an optional header value:
<s:select list="allCities"
name="selectedCity"
headerKey="-1"
headerValue="Select a City" />
For that you need to declare a variable with select box name in Action class, and put setter and getter for that. And then, when you are submitting the form, the name matches and it automatically populate in Action class.
When retrieving the data set value to same variable.Then it will populate automatically by using name.
This will happen by using params interceptor internally.
I have a situation where I would like to retrieve data from the session on a jsp using OGNL. The data in my session is stored like this:
/data/abc/-Name (key) -> ABC Inc. (value)
I can easily retrieve this from the session by doing
<s:property value="#session['/data/abc/-Name']"/>
But unfortunately, the string '/data/abc/' is a dynamic one and is stored in my action under the variable companyFolder.
How do I use this variable to get the data from the session.. something like
<s:property value="#session['%{companyFolder}-Name']"/> // this didnt work
<s:property value="#session['<s:property value="%{companyFolder}"/>-Name']"/> // this didnt work
<s:property value="#session[companyFolder + '-Name']" />
I would likely do this in the action, though, using SessionAware. This makes things easier to test, and avoids executing the JSP to see if things work.
i have a collection (an arraylist) in action class in which i m storing java mail api's Message class objects.
In jsp i want to access each message from this collection and wants to call msg.getFrom(),msg.getSubject() etc. to dipslay them in tabular form.
how to call methods on collection objects from jsp using struts2 tags or OGNL.
thanks...
Same way as in Java--just call the method. With getters, though, you access them as properties using normal JSP EL or OGNL.
<s:iterator value="msgs" var="msg">
<!-- "#" may not be required depending on Struts 2 version. -->
<s:property value="#msg.from"/>
</s:iterator>
Or:
<c:forEach items="${msgs}" var="msg">
${msg.from}
</c:forEach>
(There are a few other variations as well.)
I'm coming from a Spring MVC background on a new Grails app. I have an object that contains a list of dependent objects. On the create and edit screen, I want to edit that object and its list of objects at the same time. In Spring MVC, you could use special names to bind the form fields to items in a list. Example:
Entity { String name, List items }
<form:input name="entity.items[0].value" value="${entity.items[0].value}"/>
I've tried similar variations in my GSP create and edit forms, but no luck.
I haven't used this with tag (is it a Java taglib?), but what you are doing is along the right path. I don't think you need the entity in there, the name should be just "items[0].value"
Here is some code I have that does what you need (using HTML input tag):
<input type="text" name="subItems[0].date"/>