Pass id to the controller - spring

Question

Firstly, I am passing values from database to the table. In the first column I want to create a form that will pass the id to delete function in Controller.
<tr th:each="blg: ${all}" th:object="${blg}" >
<td>
<form th:action="#{/delete}" th:object= "${blg}" method="post">
<input type="text" th:field="${blg.id}"/>
<button type="submit">Delete</button>
</form>
</td>
<td th:text="*{title}"> title </td>
<td th:text="*{content}"> title </td>
<td th:text="*{category}"> title </td>
<td th:text="*{signature}"> title </td>
</tr>
Controller:
#GetMapping("/show")
public String show(Model model){
List<Blog> all = br.findAll();
model.addAttribute("all",all);
return "show";
}
#RequestMapping(value="/delete", method=RequestMethod.POST)
public String deletePost(#RequestParam Long id){
br.delete(id);
return "redirect:/show";
}
The thymeleaf engine doesn't map the object as this error occcurs:
java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'blg' available as request attribute.
What is the way to create a correct form in this case?

Answer 1

Update your html code as shown below:
<tr th:each="blg: ${all}" >
<td>
<form th:action="#{|/delete/${blg.id}|}" method="post">
<button type="submit">Delete</button>
</form>
</td>
<td th:text="${blg.title}"> title </td>
<td th:text="${blg.content}"> title </td>
<td th:text="${blg.category}"> title </td>
<td th:text="${blg.signature}"> title </td>
</tr>
Better to use HTTP method DELETE for delete operations.
The reason because th:object tried to look in your request attribute for the attribute blg. But blg is a result of an iteration.