Thymeleaf从视图中检索数据
[英]Thymeleaf retriving data from view
问题描述
I have a problem with accessing to data from html form with controller. 
我在使用控制器从html表单访问数据时遇到问题。 I'm getting a NullPointerException when I try to get data from html. 当我尝试从html获取数据时，出现NullPointerException 。 When I try to print username and password in html view, there is no problem, but when I try to do this in controller, the data is empty except the id that I add to object. 当我尝试在html视图中打印用户名和密码时，没有问题，但是当我尝试在控制器中执行此操作时，除了我添加到对象的id之外，数据为空。
Controller: 控制器：
@RequestMapping(value = "/kpi", method = RequestMethod.POST)
public ModelAndView showKPI(@Valid Kpi kpi,
BindingResult bindingResult, Model model) throws Exception {
if(bindingResult.hasErrors()) {
System.out.println("errors in binding");
}
model.addAttribute("kpi", kpi);
System.out.println(kpi.getId());
System.out.println(kpi.getPost().getUsername()); // Here is the NullPointer
Map<String, Kpi> map = new HashMap<String, Kpi>();
return new ModelAndView("kpi.html");
}
@RequestMapping(value = "/logged", method = RequestMethod.POST)
public ModelAndView addNewPost(@Valid Post post,
BindingResult bindingResult, Model model) throws Exception {
if (bindingResult.hasErrors()) {
return new ModelAndView("index.html");
}
...
List<Entry<String, MyValue>> map = handshake_parser.getAllSprints();
/*Loop for printing all information about sprints*/
for(Map.Entry<String, MyValue> entry : map) {
System.out.println(entry.getKey() + " " + entry.getValue().getName() + " : " + entry.getValue().getStartDate() + " to " + entry.getValue().getEndDate());
String id = entry.getKey();
}
model.addAttribute("list", map);
Kpi kpi = new Kpi();
kpi.setPost(post);
model.addAttribute("kpi", kpi);
return new ModelAndView("result.html");
}
result.html result.html
<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
<title>Spring Boot and Thymeleaf example</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
</head>
<body>
<h3>List of all sprints in board:</h3>
<table class="table table-striped">
<tr>
<th>Name</th>
<th>ID</th>
<th>StarDate</th>
<th>EndDate</th>
</tr>
<tr th:each="entry : ${list}">
<td th:text="${entry.value.name}">name</td>
<td th:text="${entry.key}">id</td>
<td th:text="${entry.value.startDate}">startDate</td>
<td th:text="${entry.value.endDate}">endDate</td>
</tr>
</table>
<form action="#" th:action="@{/kpi}" th:object="${kpi}" method="post">
<select th:field="*{id}">
<option th:each="entry : ${list}"
th:value="${entry.key}"
th:text="${entry.value.name}">
</option>
</select>
<div th:text="kpi.post.username"></div> <!-- Here is printing it well -->
<button type="submit">See KPI</button>
</form>
</body>
</html>
Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed;
How can I retrieve and use data from view that had been declared previously in controller? 如何从以前在控制器中声明的视图中检索和使用数据？
1 个解决方案
解决方案1
0 已采纳 2018-03-26 08:57:26
1) You have to add @ModelAttribute annotation to the method argument: 1）您必须在方法参数中添加@ModelAttribute批注：
public ModelAndView showKPI(@Valid @ModelAttribute Kpi kpi, BindingResult bindingResult, Model model) throws Exception {
// ...
}
2) There is no input for the username in HTML page. 2）HTML页面中没有用户名输入。 You have to add something like: 您必须添加以下内容：
<form action="#" th:action="@{/kpi}" th:object="${kpi}" method="post">
<select th:field="*{id}">
<option th:each="entry : ${list}"
th:value="${entry.key}"
th:text="${entry.value.name}">
</option>
</select>
<div th:text="kpi.post.username"></div>
<!-- THIS -->
<input th:field="*{post.username}" th:value="${kpi.post.username}" />
<button type="submit">See KPI</button>
</form>
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