Thymeleaf If Else Condition Example

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In this example, we will discuss how to perform if-else condition in Thymeleaf with an example.
Learn Thymeleaf at https://www.javaguides.net/p/thymeleaf-tutorial.html

Using Switch Case Statement

To achieve similar to if-else condition in Thymeleaf we can use th:switch attribute. 
This command is equivalent to a switch structure in Java. The following example shows how to use it:
<div th:switch="${condition}">
  <p th:case="${true}">TRUE</p>
  <p th:case="*">FALSE</p>
</div>
Thymeleaf at the first step will evaluate ${condition} expression and if the value is true it will print p tag with TRUE text. When an evaluated value is different than the true the Thymeleaf engine will generate p element with FALSE. 
The default option for th:switch is specified as th:case="*". This simple switch with default handled will work as if-else command.

Thymeleaf th:switch, th:case Attributes Example with Spring boot

In this example, we will demonstrate the usage of th:switch, th:case attributes.
Let's add below dependency to integrate Thymeleaf with Spring boot:
<dependency>
 <groupId>org.springframework.boot</groupId>
 <artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
Let's create a User class:
package net.javaguides.springboot;

public class User {
    private String userName;
    private String email;
    private String role;
    public User(String userName, String email, String role) {
        super();
        this.userName = userName;
        this.email = email;
        this.role = role;
    }
    public String getUserName() {
        return userName;
    }
    public void setUserName(String userName) {
        this.userName = userName;
    }
    public String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }
    public String getRole() {
        return role;
    }
    public void setRole(String role) {
        this.role = role;
    }
}
Now, let's create Spring MVC controller with handler method to return Thymeleaf template like:
package net.javaguides.springboot;

import java.util.ArrayList;
import java.util.List;

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

@Controller
public class UserController {

    @GetMapping("/switch-case")
    public String switchExample(Model model) {
        User user = new User("Ramesh", "ramesh@gmail.com", "ADMIN");
        model.addAttribute("user", user);
        return "switch-case";
    }
}
Here is the Thymeleaf template to demonstrates the use of a switch case statement:
<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">

<head>
    <meta charset="ISO-8859-1">
    <title>Thymeleaf switch case Demo</title>

    <link th:href="@{/css/bootstrap.min.css}" rel="stylesheet" />
</head>

<body>
    <div class="container">
        <div class="row">
            <h1>Thymeleaf swith case demo</h1>
            <h4 th:utext="${user.userName}"></h4>
            <div th:switch="${user.role}">
                <p th:case="'ADMIN'">User is an administrator</p>
                <!-- * for default case -->
                <p th:case="*">User is some other thing</p>
            </div>
        </div>

    </div>
</body>

</html>
If the User role is "Admin" then "User is an administrator" text prints on the web page.
The th:case = "*" is the default case of the th:swith/th:case structure. If all the above cases are evaluated as false the code of default case will be "rendered".

Using th:if and th:unless attributes

Thymeleaf also provides an inverse attribute of th:if which is th:unless. We can use it to construct conditional sections that work like an if-else command.
<div th:if="${condition}">
  <p>TRUE</p>
</div>
<div th:unless="${condition}">
  <p>FALSE</p>
</div>

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