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POhttp GET parameter SOMETIMES missing when using JSF
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copied!<p>I have a servlet filter that handles errors for both vanilla servlets and <code>JSF</code> pages.</p> <p>If an error is detected the user is redirected to an error page where he can give feedback. Then I try to read the value in the <code>ErrorBean</code> object. However, sometimes the error is not present - there is a 50-50 chance of the error being present.</p> <p>When I use</p> <pre><code>FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap() </code></pre> <p>it sometimes returns a map with 1 entry and sometimes an empty map. In every case, the id is passed at http level.</p> <p>I can't really reproduce what is causing this. Here is the relevant code (helper methods + empty implementations omitted). The ErrorFilter is mapped at <code>/*</code> and the ErrorBean is a session scope bean managed by JSF.</p> <p><strong>ErrorFilter</strong></p> <pre><code>public class ErrorFilter implements Filter { public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException { HttpServletRequest hreq = (HttpServletRequest) req; HttpServletResponse hres = (HttpServletResponse) resp; try { chain.doFilter(req, resp); } catch (IOException e) { handleError(e, hreq, hres); } catch (ServletException e) { handleError(e, hreq, hres); } catch (RuntimeException e) { handleError(e, hreq, hres); } } private static void handleError(Throwable e, HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { final RequestInfo requestInfo = new RequestInfo(getUri(req), req.getSession().getId(), null, null, UserFactory.getUser(), InetAddress.getByName(req.getRemoteAddr())); String token = new DecimalFormat("00000000").format(Math.abs(RANDOM.nextInt() % Integer.MAX_VALUE)); //log msg //send mail in a different thread if (!req.getRequestURI().startsWith("/faces/error.jsp")) { resp.sendRedirect("/faces/error.jsp?token=" + token); } else { //log that an infite loop occurred throw new ServletException(crapMsg, e); } } } </code></pre> <p><strong>ErrorBean</strong></p> <pre><code>public class ErrorBean implements Serializable { private String feedback; private String lastToken; public String getLastErrorCode() { return "your token: " + getToken(); } private String getToken() { final String token = (String) FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap().get("token"); //here the "token" returns null although it is sent via get. if (token != null) { if (!token.equals(lastToken)) { // reset data on token change. feedback = null; } lastToken = token; } return lastToken; } public void setFeedback(String feedback) { this.feedback = feedback; } public String getFeedback() { if (feedback == null) { feedback = getDefaultMessage(); } return feedback; } public void send() { sendMail(lastToken,feedback); } } </code></pre>

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