Spring Boot, Thymeleaf Form Error - spring

Question

I am trying to create a task creation page. There is a form where the user can enter the name, description and task status and save it. However, when I go to the page it shows me this error
There was an unexpected error (type=Internal Server Error, status=500).
Error during execution of processor 'org.thymeleaf.spring4.processor.attr.SpringInputGeneralFieldAttrProcessor' (index)
I also have a delete task in my program and that seems to work perfectly fine.
This is what my mainController looks like
#RequestMapping(value = "/save-task")
public String saveTask(#ModelAttribute("task") Task task, BindingResult bindingResult, Model model) {
task.setDateCreated(new Date());
taskService.save(task);
model.addAttribute("tasks", taskService.findAll());
model.addAttribute("task", new Task());
model.addAttribute("mode", "MODE_TASKS");
return "index";
}
#RequestMapping( value = "/delete-task")
public String deleteTask(#RequestParam (required = false) int id, Model model){
taskService.delete(id);
model.addAttribute("tasks", taskService.findAll());
model.addAttribute("mode", "MODE_TASKS");
return "index";
}
Here is the form
<div class="container text-center">
<h3>Manage Task</h3>
<hr/>
<form class="form-horizontal" method="POST" th:action="#{/save-task}" th:object="${task}">
<input type="hidden" name="id" th:field="*{id}"/>
<div class="form-group">
<label class="control-label col-md-3">Name</label>
<div class="col-md-7">
<input type="text" class="form-control" name="name" th:field="*{name}"/>
</div>
</div>
<div class="form-group">
<label class="control-label col-md-3">Description</label>
<div class="col-md-7">
<input type="text" class="form-control" name="description" th:field="*{description}"/>
</div>
</div>
<div class="form-group">
<label class="control-label col-md-3">Finished</label>
<div class="col-md-7">
<input type="radio" class="col-sm-1" th:name="finished" value="true"/>
<div class="col-sm-1">Yes</div>
<input type="radio" class="col-sm-1" th:name="finished" value="false"/>
<div class="col-sm-1">No</div>
</div>
<div class="form-group">
<input type="submit" class="btn btn-primary" value="Save"/>
</div>
</div>
</form>
</div>
</div>
Delete Task html
<tr th:each="task: ${tasks}">
<td th:text="${task.id}"></td>
<td th:text="${task.name}"></td>
<td th:text="${task.description}"></td>
<td th:text="${task.dateCreated}"></td>
<td th:text="${task.finished}"></td>
<td><a th:href="#{'delete-task?id=' + ${task.id}}"><span class="glyphicon glyphicon-trash"></span></a> </td>
</tr>
Here is a part of my Task entity
#Entity
#Table(name = "T_TASKS")
public class Task implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "ID")
private int id;
#Column(name = "NAME")
private String name;
#Column(name = "DESCRIPTION")
private String description;
#Column(name = "DATE_CREATED")
#Temporal(TemporalType.TIMESTAMP)
private Date dateCreated;
#Column(name = "FINISHED")
private boolean finished;
Here is the error in the slack trace
java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'task' available as request attribute

Answer 1

Change your controller mapping to accept GET and POST requests. You're getting the error because Spring can't bind a bean to the form. So add a bean when GET is called.
#GetMapping("/save-task")
public String addTask(Model model) {
Task task = new Task();
task.setDateCreated(new Date();
model.addAttribute("task", task);
return "save-task"; //or whatever the page is called
}
Then do your processing:
#PostMapping("/save-task")
public String saveTask(#ModelAttribute("task") Task task,
BindingResult bindingResult,
Model model) {
taskService.save(task);
model.addAttribute("mode", "MODE_TASKS");
return "index";
}
Your bean looks fine. I don't see that you use tasks in your HTML snippet, but that would go in the method mapped with #GetMapping if you're looking to just display all tasks.

Answer 2

Add the following to your controller class:
#ModelAttribute("task")
public Task newTaskObject() {
return new Task();
}
It will solve the binding problem. Also you need a post controller to handle the form submission.