How can I have a model attribute persist between redirects?
Question
I am trying to write a password reset function for a website. I am running into an issue that I am using a couple of redirects to transition from postmappings to getmappings and they dont seem to be carrying the attributes they need to with them, namely the user object that I am trying to reset the password form, here is an example of one of my mappings:
@PostMapping("/user/forgot")
public String emailCheck (@RequestParam String email, Model model){
User user = userDao.findByEmail(email);
if (user==null){
model.addAttribute("wrongEmail", true);
return "redirect:/user/forgot";
}
else {
model.addAttribute("user", user);
return "redirect:/verifysecurity";
}
}
And here is the template where I then call the user attribute:
<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org" lang="en">
<head th:replace="fragments/header :: header('Security', '')"></head>
<body>
<div th:replace="fragments/navbar :: navbar"></div>
<h1 th:if="${wrongAnswer}">Answer does not match record on file, please try again</h1>
<h1>Please answer your security question: WHat is your best friends name?</h1>
<form id="passwordForm" th:action="@{/verifysecurity}" th:method="post">
<label for="answer">Answer</label>
<br/>
<input type="text" id="answer" name="answer"/>
<input type="hidden" name="user" id="user" th:value="${user}"/>
<input type="submit" class="btn btn-block btn-primary" value="Request"/>
</form>
</body>
</html>
Then on the next mapping afterwards I get a null pointer exception for the user:
@PostMapping("/verifysecurity")
public String verify (Model model, @RequestParam User user, @RequestParam String answer){
String security = user.getSecurity_question();
if (answer.equals(security)){
model.addAttribute("user", user);
return "redirect:/reset/password";
} else {
model.addAttribute("wrongAnswer", true);
model.addAttribute("user", user);
return "redirect:/verifysecurity";
}
}
How can I fix this, and if model attributes won't work what should I be doing instead?
1 answers
solution1
2 ACCPTED 2019-03-21 17:32:08
Use spring RedirectAttributes.addFlashAttribute() , as name suggested it's stored in flashmap which internally uses user session to pass on this data to next redirect, and removes ones data is used.
Example from spring doc:
@RequestMapping(value = "/accounts", method = RequestMethod.POST)
public String handle(Account account, BindingResult result, RedirectAttributes redirectAttrs) {
// Save account ...
redirectAttrs.addFlashAttribute("message", "Account created!");
return "redirect:/accounts/{id}";
}
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