How to send data from one page to another using Thymeleaf

Question

Good day!

I have a task to write a blog with Spring Boot and Thymeleaf. Nothing special, common CRUD operations. I have a problem sending data from one HTML page to another. Answer given here: Thymeleaf send parameter from html to controller doesn't work, and I can't understand why. May be someone could help me? Thank you!

My files: Entity:

@Entity
@Table(name="PRIVATEBLOG")
public class BlogPost{
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name="Id", nullable = false)
    private Long id;

    @Column (name="Date", nullable = false)
    private LocalDate postDate;

    @Column (name="PostText", length = 960, nullable = false)
    private String postText;
setters& getters.

Controller: (only problematic methods)

@RequestMapping(value={"/showAllPosts"}, method = RequestMethod.GET)
    public String showAllPosts(Model model){
        List<BlogPost> allBlogPosts = new ArrayList<>();
        blogPostDAO.findAll().forEach(b -> allBlogPosts.add(b));
        allBlogPosts.stream().collect(Collectors.toList());
        model.addAttribute("allBlogPosts", allBlogPosts);
        return "showAllPosts";
    }
@RequestMapping(value={"/selectedPost"}, method = RequestMethod.GET)
    public String showSelectedPost(Model model, @RequestParam Long id){
        BlogPost bp = blogPostDAO.findById(id).get();
        model.addAttribute("post",bp);
        return "selectedPost";
    }

My views: showAllPosts.html

<body>
      <h2>All posts in blog:</h2>
      
      <br/><br/>
      <div>
         <table border="1">
            <tr>
               <th>Date</th>
               <th>Post text</th>
               <th>Action</th>
            </tr>
            <tr th:each ="post : ${allBlogPosts}">
                <td th:utext="${post.postDate}">...</td>
                <td th:utext="${post.postText}">...</td>
                <td>
                <form th:action = "@{/selectedPost}"
                    th:object="${post}" method = "POST">
                    <input type="hidden" th:field="${id}" /> 
                <button type="submit">Select</button>
                </form>
                </td>
            </tr>
         </table>
      </div>
      <a href="index">Home</a>
   </body>

selectedPost.html

<body>
      <h2>Selected post:</h2>
      <br/>
      <h3>Date: </h3>
      <h3 th:utext="${post.postDate}">...</h3>
      <h3>Post: </h3>
      <h3 th:utext="${post.postText}">...</h3>
      <br/>
      <form th:action = "@{/deletePost}"
	 	   th:object = "${post}" method = "POST">
          <input type="hidden" th:field="${id}">
          <button type="submit">Delete</button>
      </form>
      <form th:action = "@{/updatePost}"
			   th:object = "${post}" method = "POST">
			   <input type="hidden" th:field="${id}">
			   <button type="submit">Update</button>
      </form>
      <a href="index">Home</a>
   </body>

The problem is to send post id for selected post from showAllPosts to selectedPost.html. Invoking "showAllPosts" I obtain such kind of error:

There was an unexpected error(type=Internal Server Error, status=500). Error during execution of processor

'org.thymeleaf.spring5.processor.SpringInputGeneralFieldTagProcessor' (template: "showAllPosts" - line 25, col 42)

(it's here: <input type="hidden" th:field="${id}" /> )

UPDATE. Here is the POST method for "selectedPage":

@RequestMapping(value={"/selectedPost"}, method = RequestMethod.POST)
    public String getSelectedPost(Model model, @ModelAttribute("post") BlogPost post){
        BlogPost bp = blogPostDAO.findById(post.getId()).get();
        BlogPostForm blogPostForm = new BlogPostForm();
        blogPostForm.setId(bp.getId());
        blogPostForm.setPostDate(bp.getPostDate());
        blogPostForm.setPostText(bp.getPostText());
        model.addAttribute("post",bp);
        return "selectedPost";
}

Update 2. A little bit more from stack trace: 2018-08-24 00:09:47.188 ERROR 12204 --- [nio-8080-exec-1] org.thymeleaf.TemplateEngine : [THYMELEAF][http-nio-8080-exec-1] Exception processing template "showAllPosts": Error during execution of processor 'org.thymeleaf.spring5.processor.SpringInputGeneralFieldTagProcessor' (template: "showAllPosts" - line 25, col 42)

org.thymeleaf.exceptions.TemplateProcessingException: Error during execution of processor 'org.thymeleaf.spring5.processor.SpringInputGeneralFieldTagProcessor' (template: "showAllPosts" - line 25, col 42) at org.thymeleaf.processor.element.AbstractAttributeTagProcessor.doProcess(AbstractAttributeTagProcessor.java:117) ~[thymeleaf-3.0.9.RELEASE.jar:3.0.9.RELEASE] at org.thymeleaf.processor.element.AbstractElementTagProcessor.process(AbstractElementTagProcessor.java:95) ~[thymeleaf-3.0.9.RELEASE.jar:3.0.9.RELEASE] at org.thymeleaf.util.ProcessorConfigurationUtils$ElementTagProcessorWrapper.process(ProcessorConfigurationUtils.java:633) ~[thymeleaf-3.0.9.RELEASE.jar:3.0.9.RELEASE] at org.thymeleaf.engine.ProcessorTemplateHandler.handleStandaloneElement(ProcessorTemplateHandler.java:918) ~[thymeleaf-3.0.9.RELEASE.jar:3.0.9.RELEASE] at org.thymeleaf.engine.StandaloneElementTag.beHandled(StandaloneElementTag.java:228) ~[thymeleaf-3.0.9.RELEASE.jar:3.0.9.RELEASE] at org.thymeleaf.engine.Model.process(Model.java:282) ~[thymeleaf-3.0.9.RELEASE.jar:3.0.9.RELEASE]...

Caused by: java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'id' available as request attribute at org.springframework.web.servlet.support.BindStatus.(BindStatus.java:153) ~[spring-webmvc-5.0.5.RELEASE.jar:5.0.5.RELEASE] at org.springframework.web.servlet.support.RequestContext.getBindStatus(RequestContext.java:903) ~[spring-webmvc-5.0.5.RELEASE.jar:5.0.5.RELEASE] at org.thymeleaf.spring5.context.webmvc.SpringWebMvcThymeleafRequestContext.getBindStatus(SpringWebMvcThymeleafRequestContext.java:227) ~[thymeleaf-spring5-3.0.9.RELEASE.jar:3.0.9.RELEASE] at org.thymeleaf.spring5.util.FieldUtils.getBindStatusFromParsedExpression(FieldUtils.java:305) ~[thymeleaf-spring5-3.0.9.RELEASE.jar:3.0.9.RELEASE] at org.thymeleaf.spring5.util.FieldUtils.getBindStatus(FieldUtils.java:257) ~[thymeleaf-spring5-3.0.9.RELEASE.jar:3.0.9.RELEASE]...

java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'id' available as request attribute at org.springframework.web.servlet.support.BindStatus.(BindStatus.java:153) ~[spring-webmvc-5.0.5.RELEASE.jar:5.0.5.RELEASE] at org.springframework.web.servlet.support.RequestContext.getBindStatus(RequestContext.java:903) ~[spring-webmvc-5.0.5.RELEASE.jar:5.0.5.RELEASE] at org.thymeleaf.spring5.context.webmvc.SpringWebMvcThymeleafRequestContext.getBindStatus(SpringWebMvcThymeleafRequestContext.java:227) ~[thymeleaf-spring5-3.0.9.RELEASE.jar:3.0.9.RELEASE] at org.thymeleaf.spring5.util.FieldUtils.getBindStatusFromParsedExpression(FieldUtils.java:305) ~[thymeleaf-spring5-3.0.9.RELEASE.jar:3.0.9.RELEASE] at org.thymeleaf.spring5.util.FieldUtils.getBindStatus(FieldUtils.java:257) ~[thymeleaf-spring5-3.0.9.RELEASE.jar:3.0.9.RELEASE]...

Sorry, if it's unuseful things...

You use POST as method but your request mapping is GET. I would go for GET and use links instead of forms. selectedPost?id=12 or even more readable /posts for all posts and /posts/12 for one selected post. You can use path variables in spring for this — thopaw
– thopaw, Commented Aug 23, 2018 at 21:11
Changing POST to GET gave the same result. I have methods for GET and POST - does not work. I also tried path variables - the same result: methods don't get id. — Vladislav Kremenetsky
– Vladislav Kremenetsky, Commented Aug 23, 2018 at 21:15
I added stack trace logs (first lines of each block) at the bottom of the post. — Vladislav Kremenetsky
– Vladislav Kremenetsky, Commented Aug 23, 2018 at 22:47
try to change this <input type="hidden" th:field="${id}" /> line into <input type="hidden" th:field="${post.id}" /> — thopaw
– thopaw, Commented Aug 24, 2018 at 5:57

Xaltotun · Accepted Answer · 2018-08-24 09:49:55Z

3

I think it is worth adding a proper answer. The correct way to collect bean properties in a html form in Thymeleaf 3.0 according to this is this form th:field="*{id}". Quote:

As you can see, we are introducing a new attribute here: th:field. This is a very important feature for Spring MVC integration because it does all the heavy work of binding your input with a property in the form-backing bean.

And if you already tried that try sending the id of the post as a parameter instead of the post object. Maybe the post object must exist in the model and cannot be picked up from the iteration. Like this:

<form th:action = "@{/selectedPost(id=${post.id})}" method = "POST">
                 <button type="submit" name="select">Select</button>
            </form>

And use this in the web method like this:

public String showMethod(@RequestParam(name="id", required=false) Integer postId, Model model)

edited Aug 24, 2018 at 9:49

answered Aug 24, 2018 at 8:22

Xaltotun

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1 Comment

Xaltotun Over a year ago

Then you should accept the answer. Glad I could help.

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