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jsp form validation using bean with int

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posted 19 years ago

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I want to validate forms as shown in the Java Developers Almanac example. My problem is when I use beans with numeric values such as int. If I submit the form with String values in the int field, the page throws NumberFormatException. My validation code is never reached. What do I need to do to perform my own validation?

<%-- Instantiate the form validation bean and supply the error message map --%>
<%@ page import="org.timtroy.bean.*" %>
 
    <jsp:useBean id="form" class="org.timtroy.bean.MyForm" scope="request">
        <jsp:setProperty name="form" property="errorMessages" value='<%= errorMap %>'/>
    </jsp:useBean>
    
    <%
        // If process is true, attempt to validate and process the form
        if ("true".equals(request.getParameter("process"))) {
    %>
            <jsp:setProperty name="form" property="*" />
    <%
            // Attempt to process the form
            if (form.process()) {
                // Go to success page
                response.sendRedirect("View1.jsp");
                return;
            }
        }
    %>
    
    <html>
    <head><title>A Simple Form</title></head>
    <body>
    
    <%-- When submitting the form, resubmit to this page --%>
    <form action='<%= request.getRequestURI() %>' method="POST">
        <%-- id --%>
        <font color=red><%= form.getErrorMessage("id") %></font><br>
        Id: <input type="TEXT" name="id" value='<%= form.getId() %>'>
        <br>
    
        <%-- email --%>
        <font color=red><%= form.getErrorMessage("email") %></font><br>
        Email: <input type="TEXT" name="email" value='<%= form.getEmail() %>'>
        <br>
    
        <%-- zipcode --%>
        <font color=red><%= form.getErrorMessage("zipcode") %></font><br>
        Zipcode: <input type="TEXT" name="zipcode" value='<%= form.getZipcode() %>'>
        <br>
    
        <input type="SUBMIT" value="OK">
        <input type="HIDDEN" name="process" value="true">
    </form>
    
    </body>
    </html>
    
    <%!
        // Define error messages
        java.util.Map errorMap = new java.util.HashMap();
        public void jspInit() {
            errorMap.put(MyForm.ERR_EMAIL_ENTER, "Please enter an email address");
            errorMap.put(MyForm.ERR_EMAIL_INVALID, "The email address is not valid");
            errorMap.put(MyForm.ERR_ZIPCODE_ENTER, "Please enter a zipcode");
            errorMap.put(MyForm.ERR_ZIPCODE_INVALID, "The zipcode must be 5 digits");
            errorMap.put(MyForm.ERR_ZIPCODE_NUM_ONLY, "The zipcode must contain only digits");
        }
    %>
 
package org.timtroy.bean;
 
import java.util.*;
 
public class MyForm {
    /*  The properties */
    private int id = -1;
    private String email = "";
    private String zipcode = "";
    
    public int getId()
    {
        return id;
    }
 
    public void setId(int i)
    {
        id = i;
    }
 
    public String getEmail() {
        return email;
    }
 
    public void setEmail(String email) {
        this.email = email.trim();
    }
 
    public String getZipcode() {
        return zipcode;
    }
 
    public void setZipcode(String zipcode) {
        this.zipcode = zipcode.trim();
    }
 
    /* Errors */
    public static final Integer ERR_EMAIL_ENTER = new Integer(1);
    public static final Integer ERR_EMAIL_INVALID = new Integer(2);
    public static final Integer ERR_ZIPCODE_ENTER = new Integer(3);
    public static final Integer ERR_ZIPCODE_INVALID = new Integer(4);
    public static final Integer ERR_ZIPCODE_NUM_ONLY = new Integer(5);
 
    // Holds error messages for the properties
    Map errorCodes = new HashMap();
 
    // Maps error codes to textual messages.
    // This map must be supplied by the object that instantiated this bean.
    Map msgMap;
    public void setErrorMessages(Map msgMap) {
        this.msgMap = msgMap;
    }
 
    public String getErrorMessage(String propName) {
        Integer code = (Integer) (errorCodes.get(propName));
        if (code == null) {
            return "";
        } else if (msgMap != null) {
            String msg = (String) msgMap.get(code);
            if (msg != null) {
                return msg;
            }
        }
        return "Error";
    }
 
    /* Form validation and processing */
    public boolean isValid() {
        // Clear all errors
        errorCodes.clear();
 
        // Validate email
        if (email.length() == 0) {
            errorCodes.put("email", ERR_EMAIL_ENTER);
        } else if (!email.matches(".+@.+\\..+")) {
            errorCodes.put("email", ERR_EMAIL_INVALID);
        }
 
        // Validate zipcode
        if (zipcode.length() == 0) {
            errorCodes.put("zipcode", ERR_ZIPCODE_ENTER);
        } else if (zipcode.length() != 5) {
            errorCodes.put("zipcode", ERR_ZIPCODE_INVALID);
        } else {
            try {
                int i = Integer.parseInt(zipcode);
            } catch (NumberFormatException e) {
                errorCodes.put("zipcode", ERR_ZIPCODE_NUM_ONLY);
            }
        }
 
        // If no errors, form is valid
        return errorCodes.size() == 0;
    }
 
    public boolean process() {
        if (!isValid()) {
            return false;
        }
 
        // Process form...
 
        // Clear the form
        id = 0;
        email = "";
        zipcode = "";
        errorCodes.clear();
        return true;
    }
}
 
Error 500--Internal Server Error 
java.lang.NumberFormatException: For input string: "a"
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
at java.lang.Integer.parseInt(Integer.java:468)
at java.lang.Integer.valueOf(Integer.java:574)
at jsp_servlet.__view2._jspService(__view2.java:195)
at weblogic.servlet.jsp.JspBase.service(JspBase.java:33)
at weblogic.servlet.internal.ServletStubImpl$ServletInvocationAction.run(ServletStubImpl.java:996)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:419)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:315)
at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:6452)
at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:118)
at weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppServletContext.java:3661)
at weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestImpl.java:2630)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:219)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:178)

Ben Souther

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posted 19 years ago

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Integer.parseInt(yourString) will convert a String to an int (providing the string you pass to it can be converted to an int

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Adeel Ansari

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posted 19 years ago

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Originally posted by Ben Souther:
Integer.parseInt(yourString) will convert a String to an int (providing the string you pass to it can be converted to an int .

if can not be converted into String, he will again run into problem.
Use some utility method of your own. like below,

It is returning Integer, instead of int. Actually I prefer to use Integer when writing VOs. Because there is a lot difference between 0 and null according the the database especially. If you want to write your VO into database you wouldn't want to write null as 0. and int can not be a null.

cheers.

Ben Souther

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posted 19 years ago

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No, there's no need to change your data type.
If your user is passing non-numerics in, you want to catch that right up front.

Java now (starting with version 1.4) has regular expression tools.
You could also write a quick isInt(String) method using those.

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Adeel Ansari

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posted 19 years ago

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Yeah this sounds better.
Actually, I was not really saying to change the type

. However, I explained the case, why change to Integer.

thanks.

Tim Troy

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posted 19 years ago

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The error shown in the stacktrace is caused by the line,
.
The tag reads the form and populates the bean. If the form field contains a String and the bean field is an int, the NumberFormatException is thrown. If my jsp form bean can only use Strings, then the usefulness of setting all properties with "*" is dimminished. Is there a way to catch bad input data using this example? I understand the suggestions posted, but, how can they be applied since the jsp:setProperty tag is causing the problem before I can run my error checking code?

Ben Souther

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posted 19 years ago

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Hmm, first thought....

Second thought:

These are just a couple ideas. Not sure the second one will even compile.
I generally handle all the validation and transformation in servlets so I'm
interested in seeing if someone has a more graceful or "established best practice" way of doing this.
[ January 13, 2005: Message edited by: Ben Souther ]

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