How to retrieve the data from the database and display it on a jsp using struts

[Vidya Gupta]

Hi,

I am new to struts. I want to display all the details from a table on a jsp to user. Please help in doing these.

thanks in advance,
Vidya

In my action class am adding the data in database to a list and forwarding to a jsp page.

RetrieveDataActionClass.java
--------------------

public class RetrieveDataActionClass extends Action{

public ActionForward execute(parameters)
{
List list=new ArrayList();
String key="success";
Statement stmt = null;
ResultSet rs=null;

Connection conn=DBUtil.getDBConnection();
String query="select * from student_info";

rs = stmt.executeQuery(query);  
while (rs.next()) 
{  
list.add(rs.getString("name"));
list.add(rs.getString("phone"));
list.add(rs.getString("email"));
list.add(rs.getString("city"));
list.add(rs.getString("state"));
list.add(rs.getString("gender"));
list.add(rs.getString("branch"));
HttpSession session=request.getSession();
session.setAttribute("listname",list);
}
return mapping.findForward(key);
}
}

In my jsp am getting the data from the list and displaying using tag.

viewstudents.jsp
----------

<logic:iterate id="listid" name="listname">
    <tr>
    <td><bean:write name="listid" property="name"/></td>
    <td><bean:write name="listid" property="phone"/></td>
    <td><bean:write name="listid" property="mailId"/></td>
    <td><bean:write name="listid" property="city"/></td>
    <td><bean:write name="listid" property="state"/></td>
    <td><bean:write name="listid" property="gender"/></td>
    <td><bean:write name="listid" property="branch"/></td>
    </tr>
    </logic:iterate>

Am getting an exception if i execute the above code,

Error message
----------------

    org.apache.jasper.JasperException: An exception occurred processing JSP page /viewstudents.jsp at line 37


    37:     <logic:iterate id="listid" name="listname">
    38:     <tr>
    39:     <td><bean:write name="listid" property="name"/></td>
    40:     <td><bean:write name="listid" property="phone"/></td>


javax.servlet.ServletException: javax.servlet.jsp.JspException: Cannot find bean: "listname" in any scope

[Shankar Tanikella]

Hi Vidya,
As the exception says it all, it cannot find the bean "listname" in any scope. The default scope used should be "request scope".
So to solve the problem you have three ways [if you are using struts 1.x]

1. Put the list in the related[would have mentioned this in struts configuration file] form and get the list from the form ->best way

<logic:iterate id="listid" name="myForm" property="listname">

2. Put the list in the request in the action class not into the session
3. mention the scope explicitly in the JSP, like

<logic:iterate id="listid" name="listname" scope="session">  

[Vidya Gupta]

i also tried by using request scope as well.. but i didn't get.. please suggest me..

[Sumit Patil]

Can you please debug the code and see if the code flow is going into the while loop and setting the "listname" in session?
A simple SOP will help.

[Vidya Gupta]

debugging is not completing properly..

[Sumit Patil]

Vidya Gupta wrote:
debugging is not completing properly..

You can use System.out.println() to check.

[Vidya Gupta]

ya i checked it by writing println() statement. It is not displaying. I think it is not going into the loop.

[Sumit Patil]

Vidya Gupta wrote:
ya i checked it by writing println() statement. It is not displaying. I think it is not going into the loop.

This means the table is empty . Please check.

[Vidya Gupta]

hey the table contains records.. i dnt knw why it is displaying the errors.. Anyway thanks alot..

[Sumit Patil]

Hey check the code, your Statement object is not initialized (or have you missed to put the code where statement is initialized via connection.createStatement()).

Statement stmt = null;  
ResultSet rs=null;  
  
Connection conn=DBUtil.getDBConnection();  
String query="select * from student_info";  
  
rs = stmt.executeQuery(query);    
while (rs.next())   

This code should throw a NullPointerException since stmt is not initialized.

[Sumit Patil]

Also, please put all the database related code inside try catch block and at the end close ResultSet, Connection and the Statement.

[Vidya Gupta]

i kept in try n catch only.. Here in this post i removed it..

[S Subbu]

HI Vidhya , If This is Your Code .

public class RetrieveDataActionClass extends Action{

public ActionForward execute(parameters)
{
List list=new ArrayList();
String key="success";
Statement stmt = null;
ResultSet rs=null;

Connection conn=DBUtil.getDBConnection();
String query="select * from student_info";

rs = stmt.executeQuery(query);  
while (rs.next()) 
{  
list.add(rs.getString("name"));
list.add(rs.getString("phone"));
list.add(rs.getString("email"));
list.add(rs.getString("city"));
list.add(rs.getString("state"));
list.add(rs.getString("gender"));
list.add(rs.getString("branch"));
HttpSession session=request.getSession();
session.setAttribute("listname",list);
}
return mapping.findForward(key);
}
}

Check Once You are assigning set attribute in while loop , that is not correct.
Do One thing create Another List and add the values List to newly created list , at the end of while loop set the newly Created list to request attribute.

public ActionForward execute(parameters)
{
List list=new ArrayList();
String key="success";
Statement stmt = null;
ResultSet rs=null;

Connection conn=DBUtil.getDBConnection();
String query="select * from student_info";
st = conn.createStatement();
rs = stmt.executeQuery(query);  
List newList = new ArrayList();
while (rs.next()) 
{  
list = new ArrayList();//Initializing values List for every loop
list.add(rs.getString("name"));
list.add(rs.getString("phone"));
list.add(rs.getString("email"));
list.add(rs.getString("city"));
list.add(rs.getString("state"));
list.add(rs.getString("gender"));
list.add(rs.getString("branch"));
newList.add(list);//Added to new list
//HttpSession session=request.getSession();
//session.setAttribute("listname",list);
list = null;
}
request.setAttribute("listname",newList);//Added to Request Attribute.
return mapping.findForward(key);
}
}

At the Jsp Page

<logic:iterate id="listid" name="listname">
    <tr>
    <td><bean:write name="listid" property="name"/></td>
    <td><bean:write name="listid" property="phone"/></td>
    <td><bean:write name="listid" property="mailId"/></td>
    <td><bean:write name="listid" property="city"/></td>
    <td><bean:write name="listid" property="state"/></td>
    <td><bean:write name="listid" property="gender"/></td>
    <td><bean:write name="listid" property="branch"/></td>
    </tr>
    </logic:iterate>

Instead of above Iteration do

<logic:iterate id="listid" name="listname">
    <tr>
              <logic:iterate id='id' name='listid'>
                    <td>${id}</td>
              </logic>
    </tr>
    </logic:iterate>

[Vidya Gupta]

still am facing the same problem with the application.. am having a doubt that in my application for the above RetrieveDataActionClass, i created a empty form bean class. Is that a problem..?

[Sumit Patil]

Have you tried accessing the "listname" attribute inside your servlet (session.getAttribute("listname"))?

[Vidya Gupta]

no i didn't tried to get the list in action class..

[S Subbu]

Hi, Vidya From which jsp you are accessing this action class that contains form tag. No need to form bean for your requirement .

Is is possible paste the code form which jsp you start for accessing the given action class.

Or paste Your Error message .

[Vidya Gupta]

Error Message:
---------------

 org.apache.jasper.JasperException: An exception occurred processing JSP page /viewstudents.jsp at line 37  
  
  
    37:     <logic:iterate id="listid" name="listname">  
    38:     <tr>  
    39:     <td><bean:write name="listid" property="name"/></td>  
    40:     <td><bean:write name="listid" property="phone"/></td>  
  
  
javax.servlet.ServletException: javax.servlet.jsp.JspException: Cannot find bean: "listname" in any scope

[S Subbu]

Ok,

Your action is executed fine,i mean request coming to our action class.

If fine Paste Action Classs Code.

Problem in Your Action Class Only

[Vidya Gupta]

RetrieveDataActionClass.java
-----------------

public ActionForward execute(ActionMapping mapping,ActionForm form,HttpServletRequest request,HttpServletResponse response)throws Exception,ServletException
	 {
		    List list=new ArrayList();
		    String key="success";
		    Statement stmt = null;
			ResultSet rs=null;
			Connection conn=DBUtil.getDBConnection();
			stmt = conn.createStatement();
			String query="select * from student_info";
		 
	try{
		
		rs = stmt.executeQuery(query);  
        
		while (rs.next()) 
		{  
			
            list.add(rs.getString("name"));
            list.add(rs.getString("phone"));
            list.add(rs.getString("email"));
            list.add(rs.getString("city"));
            list.add(rs.getString("state"));
            list.add(rs.getString("gender"));
            list.add(rs.getString("branch"));
           
                      
        }

		request.setAttribute("listname",list);
        
		}
		catch(Exception e)
		{
		   e.printStackTrace();
		   System.out.println("Error occured");
		    
		}
		return mapping.findForward(key);
		}

[Swastik Dey]

Vidya,

In your class you are using the request attribute name as samplelist, but in your jsp you are using listname.

[S Subbu]

Hi, Do that Correction given by Swastik Dey

And You want to display the resul as

name phone email state city
name phone email state city
name phone email state city
name phone email state city
name phone email state city

That was not possible with your code. you have to change code to get display result as above and you need to your jsp page also.

[Vidya Gupta]

No.. i posted wrong name.. thats it..

[S Subbu]

Now Your Code Working.

If not send the whole code once from starting jsp to ending jsp .

[Vidya Gupta]

did you checked my code? if you did any changes please post here..

[Vidya Gupta]

can i send my complete code?

[S Subbu]

public ActionForward execute(ActionMapping mapping,ActionForm form,HttpServletRequest request,HttpServletResponse response)throws Exception,ServletException
	 {
		    List list=new ArrayList();
                                    List resultList = new ArrayList();
		    String key="success";
		    Statement stmt = null;
		    ResultSet rs=null;
		   		 
	try{
                               Connection conn=DBUtil.getDBConnection();
		   stmt = conn.createStatement();
		  String query="select * from student_info";
		rs = stmt.executeQuery(query);  
        
		while (rs.next()) 
		{  
            list = new ArrayList();			
            list.add(rs.getString("name"));
            list.add(rs.getString("phone"));
            list.add(rs.getString("email"));
            list.add(rs.getString("city"));
            list.add(rs.getString("state"));
            list.add(rs.getString("gender"));
            list.add(rs.getString("branch"));
           resultList.add(list);
                      
        }

		request.setAttribute("listname",resultList);
        
		}
		catch(Exception e)
		{
		   e.printStackTrace();
		   System.out.println("Error occured");
		    
		}
		return mapping.findForward(key);
		}

Please Change JSP Page Also , i already sent xterday.

[S Subbu]

If it not work, then you send complete code.

[Vidya Gupta]

Thanks again.. but i changed the action class like above n jsp also as you said yesterday only.. but am not getting the output in my system..

[Vidya Gupta]

how can i send complete code? is there any option to check attach the file?

[S Subbu]

I dont know.may be not that option (i think so)

[Vidya Gupta]

The problem is in my action class. It is not adding list to the specified scope. First i want to know whether the list contains tha values or not..

while (rs.next()) 
		{  
			
		list = new ArrayList();  
            list.add(rs.getString("name"));
            list.add(rs.getString("phone"));
            list.add(rs.getString("email"));
            list.add(rs.getString("city"));
            list.add(rs.getString("state"));
            list.add(rs.getString("gender"));
            list.add(rs.getString("branch"));
           
            resultList.add(list);  
            
        }

here my doubt is whether the statement

rs.getString("name")

is returning the different names is that column or not? How to see the different names in that column?
I used

System.out.println("rs.getString("name"));

statement. But it didn't work. Please help me..

[Sumit Patil]

Have you created a formbean? If yes, use its property to get the details in jsp page.
See this link for more details.
Do let us know in case of any issue.

[Vidya Gupta]

i created an empty formbean without any properties.. because am getting the details from the database, so i thought there is no need of formbean.

[Sumit Patil]

Just follow the link, the author has given step by step details for displaying the data in jsp using logic iterate.
Even though you are getting the details from the db, you need to create the formbean and populate its properties from db results since logic iterate will look for this formbean in the request scope (Experts please correct me if i am wrong).
You also need to define this form bean in the struts-config.xml file.

[S Subbu]

System.out.println("rs.getString("name"));

Hi, why you are using double quote just print as

System.out.println(rs.getString("name"));

For Your Requirement Don't need Form Bean?You have Empty Form Bean that's not a problem.

To Check Your List has elements or not just print list after while loop

System.out.println(resultList);

Check First resultList contains elements or not.

[S Subbu]

logic iterate will look for this formbean in the request scope

Sumit , logic:iterate iterate like for loop, it takes array,list,map etc..

No need to populate db result to form beans.

[Vidya Gupta]

am sorry to say this again.. still the data is not displaying.. I changed my code as per the above link,

Student.java
-------------

public class Student 
{
	
	public String name;
	public String city;
	public String state;
	public String phone;
	public String mailId;
	public String gender;
	public String branch;

//setters and getters
}

RetrieveFormBean.java
-----------------

public class RetrieveFormBean extends ActionForm{

	 private List<Student> stud=new ArrayList<Student>();
	 
	    public List<Student> getStud() {
	        return stud;
	    }
	 
	    public void setStud(List<Student> emp) {
	        this.stud = stud;
	    }
	 
	 
	    public RetrieveFormBean() {
	        super();
	 
	    }
	 
	 
	}

RetrieveDataActionClass.java
-----------------------

public ActionForward execute(ActionMapping mapping,ActionForm form,HttpServletRequest request,HttpServletResponse response)
	 {
 
		    RetrieveFormBean formbean=(RetrieveFormBean)form;
		    ArrayList list=new ArrayList();
		    String key="success";
		    Statement stmt = null;
			ResultSet rs=null;
			Connection conn=DBUtil.getDBConnection();
			stmt = conn.createStatement();
			String query="select * from student_info";
		 
		
		rs = stmt.executeQuery(query);  
        
		while (rs.next()) 
		{  
			
  
            list.add(rs.getString("name"));
            list.add(rs.getString("phone"));
            list.add(rs.getString("email"));
            list.add(rs.getString("city"));
            list.add(rs.getString("state"));
            list.add(rs.getString("gender"));
            list.add(rs.getString("branch"));
            formbean.setStud(list); //added the list to formbean object
}
}

viewstudents.jsp
--------------------
// using formbean

<logic:iterate id="listid" name="RetrieveFormBean" property="stud">
    <tr>  
    <td><bean:write name="listid" property="name"/></td>  
    <td><bean:write name="listid" property="phone"/></td>  
    <td><bean:write name="listid" property="mailId"/></td>  
    <td><bean:write name="listid" property="city"/></td>  
    <td><bean:write name="listid" property="state"/></td>  
    <td><bean:write name="listid" property="gender"/></td>  
    <td><bean:write name="listid" property="branch"/></td>  
    </tr>  
    </logic:iterate> 

Am extremely sorry for irritating you all like this for a small requirement. But am new to struts and trying to learn.. Thanks..

[Vidya Gupta]

thanks subbu.. ill check it..

[Vidya Gupta]

the values are not displaying on the console. I think it is not at all going to Action class. because not only this statement System.out.println(resultList); is not executing.. simple println statements like System.out.println("executing"); also not displaying the message on the console. I don't know whether it is going to action class or not..