Getting started with thymeleaf

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Remarks

Thymeleaf is a template engine, a library written in JAVA. It allows a developer to define a HTML, XHTML or HTML5 page template and later fill it with data to generate final page. Therefore it realizes a Model-View part of a Model-View-Controller pattern.

Thymeleaf's important design principle is that a template itself has to be properly written (X)HTML.

Versions

VersionDateLatest ReleaseDate
3.x.x2016-05-083.0.62017-05-07
2.x.x2012-02-092.1.52016-07-11

Ajax form submition with Jquery

To submit form via Ajax with Jquery :

    <div id="yourPanel" th:fragment="yourFragment">  
        <form id="yourForm" method="POST" 
              th:action="@{/actions/postForm}"
              th:object="${yourFormBean}">
        <div class="form-group">
            <label for="param1"></label>
            <input class="form-component" type="text" th:field="*{param1}" />
        </div>
        <div class="form-group">
            <label for="param2"></label>
            <input class="form-component" type="text" th:field="*{param2}" />
        </div>
        <div class="form-group">
            <label for="param3"></label>
            <input class="form-component" type="checkbox" th:field="*{param3}" />
        </div>

        <button type="submit" class="btn btn-success">Save</button>
        <a href='#' class="btn btn-default">Cancel</a>
    </form>
    </div>

<script th:inline="javascript">
    /*<![CDATA[*/
    $(document).ready(function () {
        /*[+
         var postUrl = [[@{/actions/postForm(
         additionalParam=${#httpServletRequest.getParameter('additionalParam')}
         )}]]; 
         +]*/
        $("#yourForm").submit(function (e) {
            e.preventDefault();
            $.post(postUrl,
                    $(this).serialize(),
                    function (response) {
                        var isErr = 'hasError';
                        // when there are an error then show error
                        if (response.indexOf(isErr) > -1) {
                            $("#yourPanel").html(response);
                        } else {
                            var formData = $("#yourForm").serializeArray(),
                                    len = formData.length,
                                    urlEnd = '';
                            for (i = 0; i < len; i++) {
                                urlEnd += formData[i].name + '=' + encodeURIComponent(formData[i].value) + '&';
                            }

                            /*[+
                             var urlReplacement = [[@{/another/page(
                             additionalParam=${#httpServletRequest.getParameter('additionalParam')}
                             )}]] + urlEnd;
                             +]*/

                            window.location.replace(urlReplacement);
                        }
                    }
            );
            return false;
        });
    });
    /*]]>*/
</script>
 

YourFormBean class :

@lombok.Getter
@lombok.Setter
@lombok.NoArgsConstructor
public class YourFormBean {
    private String param1;
    private String param2;
    private boolean param3;
}
 

Controller code :

@RequestMapping(value = "/actions/postForm", method = RequestMethod.POST) 
public String saveForm(Model model, 
        @RequestParam("additionalParam") Integer additionalParam, 
        @Valid @ModelAttribute("yourFormBean") YourFormBean yourFormBean,
        BindingResult bindingResult,
        RedirectAttributes redirectAttributes) {
    if (bindingResult.hasErrors()) {
        model.addAttribute("hasError", true);
        return "your/template :: yourFragment";
    }
    redirectAttributes.addAttribute("additionalParam", additionalParam);
    
    return "redirect:/another/page";
}
 

Configuration

To get started with Thymeleaf visit official download page.

Maven dependency

<dependency> 
  <groupId>org.thymeleaf</groupId>
  <artifactId>thymeleaf</artifactId> 
  <version>3.0.1.RELEASE</version> 
</dependency>
 

Gradle dependency

compile group: 'org.thymeleaf', name: 'thymeleaf', version: '3.0.1.RELEASE'
 

Example configuration

Starting from version 3.0, Thymeleaf supports only Java config.

public ViewResolver viewResolver() {
    ThymeleafViewResolver resolver = new ThymeleafViewResolver();
    resolver.setTemplateEngine(templateEngine());
    resolver.setCharacterEncoding("UTF-8");
    resolver.setContentType("text/html; charset=UTF-8");
    return resolver;
}
 

In viewResolver() method you can setup e.g. encoding and content type for views. more information

public TemplateEngine templateEngine() {
    SpringTemplateEngine engine = new SpringTemplateEngine();
    engine.setTemplateResolver(templateResolver());
    return engine;
}
 

In templateEngine() , you can add custom dialects. For example to add Spring Security dialect you can do this like this engine.addDialect(new SpringSecurityDialect());

public ITemplateResolver templateResolver() {
    SpringResourceTemplateResolver resolver = new SpringResourceTemplateResolver();
    resolver.setApplicationContext(applicationContext);
    resolver.setPrefix("/views/");
    resolver.setSuffix(".html");
    resolver.setTemplateMode(TemplateMode.HTML);
    resolver.setCharacterEncoding("UTF-8");
    return resolver;
}
 

Look at setter for prefix and suffix in templateResolver() method. It tells Thymeleaf that, every time controller will return view, Thymeleaf will look these names that html in webapp/views/ directory and append .html suffix for you.

Example

@RequestMapping(value = "/")
public String homePage() {
    return "foo/my-index";
}
 

Thymeleaf will be looking html named my-index.html in webapp/views/foo/ directory. According to example configuration above.

Form Submission

Form object

package formSubmission;

public class Person {

    private String name;
    private int age;

    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name= name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }

}
 

Controller

package formSubmission;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PostMapping;

@Controller
public class FriendsController {

    @GetMapping("/friends")
    public String friendForm(Model model) {
        model.addAttribute("personForm", new Person());
        return "friendsForm";
    }

    @PostMapping("/friends")
    public String submissionResult(@ModelAttribute("personForm") Person person) {
        return "result";
    }

}
 

friendsForm.html

<!DOCTYPE HTML>
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <title>Friend form</title>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
</head>
<body>
    <h1>Friend Form</h1>
    <form th:action="@{/friends}" th:object="${personForm}" method="post">
        <p>Name: <input type="text" th:field="*{name}"/></p>
        <p>Age: <input type="number" th:field="*{age}"/></p>
        <p><input type="submit" value="Submit"/></p>
    </form>
</body>
</html>
 

result.html

<!DOCTYPE HTML>
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <title>Submission result</title>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
</head>
<body>
    <h1>th:text="'My friend ' + ${personForm.name} + ' is ' + ${personForm.age} + ' years old'"</h1>
</body>
</html>
 

Replacing fragments with ajax

If you want to replace parts of your website, ajax is an easy way to do it.

The website.html where you want to replace the content based on the selected value:

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml"
  xmlns:th="http://www.thymeleaf.org">

    <head>
        <title>Index</title>
    </head>

    <body>
        <select id="selection">
            <option>Content 1</option>
            <option>Content 2</option>
        </select>

        <div id="replace_div">
            Content goes here
        </div>

        <!-- JQury from Google CDN -->
        <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>

        <script>
            $(document).ready(function () {

                //call function when page is loaded
                getContent();

                //set on change listener
                $('#selection').change(getContent);

                function getContent() {

                    //create url to request fragment
                    var url = /content/;
                    if ($('#selection').val() === "Content 1") {
                        url = url + "content1";
                    } else {
                        url = url + "content2";
                    }

                    //load fragment and replace content
                    $('#replace_div').load(url);
                }
            })
        </script>
    </body>
</html>
 

And the content.html with the fragments you want to include based on the selected value:

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:th="http://www.thymeleaf.org">
    <head>
    </head>

    <body>
        <div th:fragment="content1">
            This is Content 1
        </div>

        <div th:fragment="content2">
            This is Content 2
         </div>
    </body>
</html>
 

Last but not least the Spring MVC ContentController.java:

@Controller
@RequestMapping("content")
public class ContentController {

    @RequestMapping("")
    public String loadContent() {
        return "website";
    }

    @RequestMapping("content1")
    public String getContent1() {
        return "content :: content1";
    }

    @RequestMapping("content2")
    public String getContent2() {
        return "content :: content2";
    }
}
 

Using checkboxes

Example method in controller

@RequestMapping(value = "/test")
public String showCheckbox(Model model) {
    boolean myBooleanVariable = false;
    model.addAttribute("myBooleanVariable", myBooleanVariable);
    return "sample-checkbox";
}
 

View: sample-checkbox.html

<input 
      type="checkbox" 
      name="myBooleanVariable" 
      th:checked="${myBooleanVariable}"/>
 

Do not use th:name for checboxes, just name

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Wednesday, June 14, 2017
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