Getting null from request.getAttribute()

Question

I have a .jsp file that sends data via the post method to a servlet, but when i try to access the data in the servlet via request.getAttribute(), it prints out "null"

my .jsp file looks like this:

            <form name="update" action="UpdateServlet" method="post"
            accept-charset="utf-8">
            <label>Name:</label><input type="text" name="input_name"    id="input_name"><br>
            <label>Beschreibung:</label> <input type="text" name="input_beschreibung" id="input_beschreibung"><br>
            <input type="hidden" name="input_id" id="input_id">
            <input type="submit" value="Okay">
            <button type="button" onclick="closeDialog()">Abbrechen</button>
            </form>

my servlet looks like this:

public class UpdateServlet extends HttpServlet {

@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    response.setContentType("text/html");

    System.out.println((String)request.getAttribute("input_id"));
    System.out.println((String)request.getAttribute("input_name"));
    System.out.println((String)request.getAttribute("input_beschreibung"));

    RequestDispatcher rd=request.getRequestDispatcher("LoadServlet");  
    rd.forward(request, response);

}

part of web.xml:

  <servlet>
  <servlet-name>UpdateServlet</servlet-name>
  <servlet-class>wochenplaner.UpdateServlet</servlet-class>
  </servlet>
  <servlet-mapping>
  <servlet-name>UpdateServlet</servlet-name>
  <url-pattern>/UpdateServlet</url-pattern>
  </servlet-mapping>

i dont understand why the attributes of the request are empty. Thanks in advance!

score 0 · Accepted Answer · edited May 23 '17 at 11:44

You are confusing request.getAttribute("") and request.getParameter(""). You need to use the latter:

public class UpdateServlet extends HttpServlet {

@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    response.setContentType("text/html");

    System.out.println(request.getParameter("input_id"));
    System.out.println(request.getParameter("input_name"));
    System.out.println(request.getParameter("input_beschreibung"));

    RequestDispatcher rd=request.getRequestDispatcher("LoadServlet");  
    rd.forward(request, response);

}

See here for some further discussion:

https://stackoverflow.com/a/5243833/1356423

score 0 · Answer 2 · answered Dec 16 '15 at 15:37

0

try this:

request.getParameter("input_id");

answered Dec 16 '15 at 15:37

Rahim Dastar

1,259
1
9
15

score 0 · Answer 3 · edited May 23 '17 at 12:03

0

You should be using request.getParameter() not request.getAttribute()

Difference between getAttribute() and getParameter()

edited May 23 '17 at 12:03

Community

1
1

answered Dec 16 '15 at 15:37

Ruelos Joel

2,209
3
19
33

Getting null from request.getAttribute()

3 Answers3