Question

The following snippet submits a caption to the database. After filling in the text , i click submit but to my surprise always a null goes to the table. I have metioned the servlet code and the html design below:

<form method="post" action="Handler" enctype="multipart/form-data">
        <table>
            <tr>
                <td> <strong> Leave a caption </strong>  </td>
                <td> <input type="text" name="caption box" size="40" /></td>
            </tr>

            <tr colspan="2">
                <td> <input type="submit" value="submit caption"/> </td>
            </tr>
        </table>
    </form>

Servlet

String caption = request.getParameter("caption box"); // get the caption from the caption field
HandleCaption hc = new HandleCaption(caption,emailOfTheUser,fileName);
hc.SubmitCaptionToTheDatabase(); 

Class

public class HandleCaption {
private String Caption = null;
private String UserEmail = null;
private String NameOfThe = null;

public HandleCaption(String caption,String email,String filename) {
    Caption = caption;
    UserEmail = email;
    NameOfThe = filename;
}

public void SubmitCaptionToTheDatabase() {
    try {
        Context context = new InitialContext();
        DataSource ds = (DataSource)context.lookup("java:comp/env/jdbc/DS");
        Connection connection = ds.getConnection();
        String sqlQuery = "insert into CAPTIONS values ('" + UserEmail + "','" + NameOfThe + "','" + Caption + "')";
        PreparedStatement statement = connection.prepareStatement(sqlQuery);
        int x = statement.executeUpdate();
    }catch(Exception exc) {
        exc.printStackTrace();
    }
}

}

I tried printing the value the text-field returned in the servlet which even the printed null. Why the text-field returns null ?

Answer 1

i’m not sure why this happens but has happened to me once or twice..
i your Caption class Handle Caption, declare it as

private String Caption = "";
private String UserEmail = "";
private String NameOfThe = "";

i know it looks like a dumb answer to the question as in constructor you are actually referring to the value that is passed but i have experienced this and thats the solution for me.please try and reply!!

Update: sorry for adressing the question wrongly
its due to encoding type, will read about why its happening.. but just remove encoding type and it works..tried on sample code

Update : multipart/form-data encoded requests are indeed not by default supported by the Servlet API prior to version 3.0. The Servlet API parses the parameters by default using application/x-www-form-urlencoded encoding. When using a different encoding, the request.getParameter() calls will all return null.