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Struts

how to display database values in a table

Greenhorn

Posts: 18

posted 14 years ago

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Hi dear,

I am trying to disply the product column from the database into a table. I am able to add the items to the ArrayList
But the items are not being displayed in the jsp. My action class is as follows:

package net.astralpharma;
import com.opensymphony.xwork2.ActionSupport;
import java.sql.*;
import java.util.*;

public class Productdisplay extends ActionSupport
	{
	private String productname;
	private List<Product> productsdealt;
	
	
	public String execute() throws Exception{
	
		String url = "jdbc:mysql://localhost:3306/";
    	String dbname="astraldb";
    	String driverName="org.gjt.mm.mysql.Driver";
    	String userName="root";
    	String password="root";
    	Connection con=null;
    	PreparedStatement stat =null;
    	
    	try
    	{
    		Class.forName(driverName);
    		System.out.println("Driver Loaded");
			con = DriverManager.getConnection("jdbc:mysql://localhost:3306/astraldb","root","root" );
			System.out.println("Database is connected");
			String query="Select productname from supplier_proddetails";
    		stat = con.prepareStatement(query);
			System.out.println(stat);
			ResultSet rs = stat.executeQuery();
			System.out.println("rs"+ rs);
			while(rs.next())
			{
				System.out.println("inside while");
				Product item = new Product();
				item.setProductname(rs.getString("productname"));
				List<Product> productsdealt = new ArrayList<Product>();
				productsdealt.add(item);
				System.out.println("item added successfully");
				return "success";
			}
		}
		catch(Exception ex){
		ex.printStackTrace();
		System.out.println("Exception" + ex.getMessage());
		}
		return "error";
		}
		
		public String getProductname() {
	        return  productname;
	    }

public void setProductname(String productname) {
	        this.productname = productname;
	    }
	    
	    public List<Product> getProductsdealt(){
	    	return productsdealt;
	    }
	    
	    public void setProductsdealt(List<Product> productsdealt){
	    	this.productsdealt = productsdealt; 
	    }
	}

The jsp is not printing the product name stored in the database. The jsp is as follows:

Prashant Singh

David Newton

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posted 14 years ago

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Line 38 creates a new, local "productsdealt" list. The action property is never set or filled, so there's nothing to display.

From a stylistic standpoint it's more common to use names like "productsDealt", which is arguably easier to read.

Amandeep Singh

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Posts: 856

posted 14 years ago

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So either you can set "productsdealt" to session scope or request scope. And accordingly retrieve it in jsp.

SCJP 1.4, SCWCD 5, SCBCD 5, OCPJWSD 5,SCEA-1, Started Assignment Part 2
My blog- http://rkydesigns.blogspot.com

David Newton

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posted 14 years ago

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@Amandeep: That's not the preferred mechanism in Struts 2--there's no reason to set something to a JEE scope unless you have a specific requirement to do so.

Amandeep Singh

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posted 14 years ago

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so what is the recommended approach to do this in struts 2?

SCJP 1.4, SCWCD 5, SCBCD 5, OCPJWSD 5,SCEA-1, Started Assignment Part 2
My blog- http://rkydesigns.blogspot.com

David Newton

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posted 14 years ago

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Expose an action property, as the OP did in the second code snippet (but never filled it with values).

Prashant K. Singh

Greenhorn

Posts: 18

posted 14 years ago

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Hi David,

I modified the action class and the jsp a bit and now I am able to print the output on the jsp.

But Hulloa there is a problem. Also every time I hit the refresh button, the output gets increased by one ie if i have bariton as output then it becomes barition bariton.

I am again posting the code:

Here is the Productdisplay.java

package net.astralpharma;
import com.opensymphony.xwork2.ActionSupport;
import java.sql.*;
import java.util.*;

public class Productdisplay extends ActionSupport
	{
	private String productName;
	private static List<Product> products = new ArrayList<Product>();
	
	public String populate()
	{
		productName=getProductName();
		return "populate";
	}
		
	public String execute() throws Exception{
	
		String url = "jdbc:mysql://localhost:3306/";
    	String dbname="astraldb";
    	String driverName="org.gjt.mm.mysql.Driver";
    	String userName="root";
    	String password="root";
    	Connection con=null;
    	PreparedStatement stat =null;
    	
    	try
    	{
    		Class.forName(driverName);
    		System.out.println("Driver Loaded");
			con = DriverManager.getConnection("jdbc:mysql://localhost:3306/astraldb","root","root" );
			System.out.println("Database is connected");
			String query="Select productname from supplier_proddetails";
    		stat = con.prepareStatement(query);
			System.out.println(stat);
			ResultSet rs = stat.executeQuery();
			System.out.println("rs"+ rs);
			while(rs.next())
			{
				System.out.println("inside while");
				Product productName = new Product();
				String s= rs.getString("productName");
				System.out.println("Productname" + s);
				productName.setProductName(rs.getString("productName"));
				products.add(productName);
				System.out.println("item added successfully");
				
			}
                                                return "success";
		}
		catch(Exception ex){
		ex.printStackTrace();
		System.out.println("Exception" + ex.getMessage());
		}
		return "error";
		}
		
		public String getProductName() {
	        return  productName;
	    }

public void setProductName(String productName) {
	        this.productName = productName;
	    }
	    
	    public List<Product> getProducts(){
	    	return products;
	    }
	    
	    public void setProducts(List<Product> products){
	    	this.products = products; 
	    }
	}

Here is the Product.java

Here is the producthandles.jsp

Prashant Singh

David Newton

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posted 14 years ago

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Are you using Spring?

It's difficult to understand code's intent when there are ambiguities--for example, the action method creates a local variable called "productName", and the action has a property called "productName", and they're different types.

Amandeep Singh

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Posts: 856

posted 14 years ago

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David Newton wrote:Expose an action property, as the OP did in the second code snippet (but never filled it with values).

As i am a newbie to Struts 2. Just a question, in the previous code how Prashant is exposing the 'products' to the jsp.
Because inside the ActionSupport, we are not exposing it through any reference.

SCJP 1.4, SCWCD 5, SCBCD 5, OCPJWSD 5,SCEA-1, Started Assignment Part 2
My blog- http://rkydesigns.blogspot.com

David Newton

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posted 14 years ago

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how Prashant is exposing the 'products' to the jsp

Amandeep Singh

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posted 14 years ago

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this i know. i actually meant is this exposed as a action property inside struts-config.xml

as i know struts 1. this feature is available only in struts 2.

please correct me if i am wrong.

SCJP 1.4, SCWCD 5, SCBCD 5, OCPJWSD 5,SCEA-1, Started Assignment Part 2
My blog- http://rkydesigns.blogspot.com

David Newton

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posted 14 years ago

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You're not wrong--this is Struts 2, as was the original question.

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