dynamically loop through form parameters in servlet

[John Schretz]

I have a html table that has 4 columns. This table is built from the database and can have any number of rows. For the first column of every row there is a check box. What I need to do is when this form gets posted to my servlet i need to loop though and get the parameters for each row of the table and update the corresponding row in my database. Below is the form i am using. I am not sure the best way to do this in the servlet and i am looking for some direction. Also does each of the rows components have to have a different name?

<form action="<c:url value='savebrands' />" name="saveBrands" method="post" STYLE="margin:0; padding:0;">
  <table width="694"  border="0" align="left" cellpadding="1" cellspacing="1" style="border: 1px solid #000000">
    <tr>
      <td width="87" height="19" align="center" valign="middle" bgcolor="#787878"><span class="style1">Show On Web</span></td>
      <td width="197" align="center" valign="middle" bgcolor="#787878"><span class="style1">Brand Name</span></td>
      <td align="center" valign="middle" bgcolor="#787878"><span class="style1">Nav Image Filename</span></td>
      <td align="center" valign="middle" bgcolor="#787878"><span class="style1">Brand Header Filename</span></td>
    </tr>
    <c:forEach var="vendor" items="${vendors}">
      <tr>
        <td height="24" align="center" valign="middle">
          <input type="checkbox" name="${vendor.vCode}" id="checkbox" />
        </td>
        <td height="24" align="left" valign="middle">${vendor.vName}</td>
        <td width="198" height="24" align="center" valign="middle"><input type="text" name="${vendor.vLogo}" id="textfield" value="${vendor.vLogo}" /></td>
        <td width="197" align="center" valign="middle"><input type="text" name="${vendor.vHeader}" id="textfield" value="${vendor.vHeader}" /></td>
      </tr>
    </c:forEach>
    <tr>
      <td height="4" colspan="4" align="right" valign="middle"><hr /></td>
    </tr>
    <tr>
      <td height="42" colspan="4" align="right" valign="middle">
          <input name="editBtn" type="image" src="adminImages/save.gif" width="100" height="40" />
    </tr>
  </table>
</form>

Servlet attempt

    
public class SaveBrandsServlet extends HttpServlet
{
 
public void doPost(HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException
{
HttpSession session = request.getSession();

   Enumeration keys = request.getParameterNames();
   while (keys.hasMoreElements() )
   {
      String key = (String)keys.nextElement();
      System.out.println(key);
 
      //To retrieve a single value
      String value = request.getParameter(key);
      System.out.println(value);
 
      // If the same key has multiple values (check boxes)
      String[] valueArray = request.getParameterValues(key);
      
      for(int i = 0; i > valueArray.length; i++){
      System.out.println("VALUE ARRAY" + valueArray[i]);
      }
   }
 
AdminUser user = (AdminUser)session.getAttribute("user");
 
String url = "";
 
if(user == null){
url = "/adminLogin.jsp";
}
else{
ArrayList<Vendor> vendors = VendorDB.selectVendors();
session.setAttribute("vendors", vendors);
session.setAttribute("user", user);
url = "/brands.jsp";
}
 
RequestDispatcher dispatcher =
getServletContext().getRequestDispatcher(url);
dispatcher.forward(request, response);
}
}

[Bear Bibeault]

If you name all the fields the same, you can get an array of the values with request.getParameterValues(), but how would tell which belongs to which row? Order is not guaranteed.

Is the vCode value unique to each row? If so, you could incorporate it into the names used on that row.

[John Schretz]

yes vCode is unique. Should i also put id's on the form fields and have them with unique values or do i not even need the id's?

[Bear Bibeault]

id's are for client-side code. If you don't need to refer to the elements in JavaScript code, id's are not needed.

[John Schretz]

With the help of Bear

thank you Bear.

If any one is having the same problem this was my resolution:
Should anyone see that it can be improved in any way please post a response
all my fields were named the same with the vendorcode appended on the end to diferentiate the rows.

Form:

<form action="<c:url value='savebrands' />" name="saveBrands" method="post" STYLE="margin:0; padding:0;">
  <table width="694"  border="0" align="left" cellpadding="1" cellspacing="1" style="border: 1px solid #000000">
    <tr>
      <td width="87" height="19" align="center" valign="middle" bgcolor="#787878"><span class="style1">Show On Web</span></td>
      <td width="197" align="center" valign="middle" bgcolor="#787878"><span class="style1">Brand Name</span></td>
      <td align="center" valign="middle" bgcolor="#787878"><span class="style1">Nav Image Filename</span></td>
      <td align="center" valign="middle" bgcolor="#787878"><span class="style1">Brand Header Filename</span></td>
    </tr>
    <c:forEach var="vendor" items="${vendors}">
      <tr>
        <td height="24" align="center" valign="middle">
          <input type="checkbox" name="field_${vendor.vCode}" />
        </td>
        <td height="24" align="left" valign="middle">${vendor.vName}</td>
        <td width="198" height="24" align="center" valign="middle">
        <input type="text" name="field_${vendor.vCode}" id="textfield" value="${vendor.vLogo}" /></td>
        <td width="197" align="center" valign="middle">
        <input type="text" name="field_${vendor.vCode}" id="textfield" value="${vendor.vHeader}" /></td>
      </tr>
    </c:forEach>
    <tr>
      <td height="4" colspan="4" align="right" valign="middle"><hr /></td>
    </tr>
    <tr>
      <td height="42" colspan="4" align="right" valign="middle">
          <input name="editBtn" type="image" src="adminImages/save.gif" width="100" height="40" />
    </tr>
  </table>
</form>
    

Servlet:

   
 
public class SaveBrandsServlet extends HttpServlet
{
 
public void doPost(HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException
{
HttpSession session = request.getSession();
 
String showWeb = "";
String navImage = "";
String brandHeader = "";

ConnectionPool pool = ConnectionPool.getInstance();
Connection connection = pool.getConnection();
 
Enumeration keys = request.getParameterNames();
while (keys.hasMoreElements() )
{
String key = (String)keys.nextElement();
System.out.println(key);
 
String vCode = key.substring(key.indexOf("_") +1);
 
String[] valueArray = request.getParameterValues(key);
 
int count = valueArray.length;
for(int i = 0; i < valueArray.length; i++){
 
String field = valueArray[i];
 
if(count == 3){
if(i == 0){
showWeb = field;
if(showWeb.equalsIgnoreCase("on")){
showWeb = "Y";
}
else{
showWeb = "N";
}
}
else if(i == 1){
navImage = field;
}
else if(i == 2){
brandHeader = field;
}
}
else{
showWeb = "N";
 
if(i == 0){
navImage = field;
}
else if(i == 1){
navImage = field;
}
}
}
String uStatement = "UPDATE VENDORS SET SHOW_ON_SITE = "+"\"" +showWeb+ "\"," + 
" VENDORIMAGE = "+ "\"" +navImage+ "\" ," + " VENDOR_HEADER_IMAGE = "+ "\"" +brandHeader+ "\" WHERE VENDORCODE = "+"\"" +vCode+"\"";
 
System.out.println(uStatement);
try {
int res = connection.createStatement().executeUpdate(uStatement);
} 
catch (SQLException e) {
e.printStackTrace();
}
 
}

try{
connection.close();
}
catch(Exception e){
e.getMessage();
}
 
AdminUser user = (AdminUser)session.getAttribute("user");
 
String url = "";
 
if(user == null){
url = "/adminLogin.jsp";
}
else{
ArrayList<Vendor> vendors = VendorDB.selectVendors();
session.setAttribute("vendors", vendors);
session.setAttribute("user", user);
url = "/brands.jsp";
}
 
RequestDispatcher dispatcher =
getServletContext().getRequestDispatcher(url);
dispatcher.forward(request, response);
}
}
 

[ October 26, 2008: Message edited by: John Schretz ]

[Bear Bibeault]

Thanks for posting back your solution! It's sure to help future posters running into similar needs.

[John Schretz]

Anytime HTH