Solving the Mysterious Case of Springboot Thymeleaf Form Submission: NULL and Blank Values NOT Showing Entered Values

Are you tired of scratching your head trying to figure out why your Springboot Thymeleaf form submission is showing NULL and blank values instead of the entered values? Well, you’re not alone! This frustrating issue has plagued many developers, and today, we’re going to crack the code and get to the bottom of it. Buckle up, folks, and let’s dive in!

Understanding the Problem

Before we start troubleshooting, let’s take a step back and understand the anatomy of a Thymeleaf form submission. When you submit a form in Thymeleaf, the data is sent to the server as a POST request. The server-side controller then processes the request and maps the form data to a Java object using Spring’s @ModelAttribute annotation.

However, when you’re facing the issue of NULL and blank values, it means that the data is not being properly mapped to the Java object. But why? Let’s explore the possibilities:

• Incorrect form binding: The form fields might not be bound correctly to the Java object, resulting in NULL values.
• Lack of getters and setters: Without proper getters and setters in the Java object, Thymeleaf cannot populate the object with the form data.
• Invalid Thymeleaf syntax: A simple typo or incorrect syntax in the Thymeleaf template can cause the form submission to fail.
• Spring configuration issues: Misconfigured Spring settings can prevent the form data from being properly processed.

Debugging and Troubleshooting

Now that we’ve identified the potential causes, let’s start debugging and troubleshooting! Follow these steps to identify the root cause of the issue:

1. Check the Java object: Verify that the Java object has proper getters and setters for each form field. Make sure the field names match exactly with the form field names.

2. Verify Thymeleaf syntax: Inspect the Thymeleaf template for any typos or incorrect syntax. Use the Thymeleaf debugger to check for any errors.

3. Check the form binding: Ensure that the form fields are correctly bound to the Java object using the th:field attribute.

4. Review Spring configuration: Verify that the Spring configuration is correct, including the @EnableWebMvc annotation and the correct view resolver settings.

Solutions and Workarounds

Now that we’ve identified and troubleshot the issue, let’s implement the solutions and workarounds:

Solution 1: Adding getters and setters

Make sure your Java object has proper getters and setters for each form field. For example:

public class User {
  private String firstName;
  private String lastName;

  public String getFirstName() {
    return firstName;
  }

  public void setFirstName(String firstName) {
    this.firstName = firstName;
  }

  public String getLastName() {
    return lastName;
  }

  public void setLastName(String lastName) {
    this.lastName = lastName;
  }
}

Solution 2: Correcting Thymeleaf syntax

Double-check your Thymeleaf template for any typos or incorrect syntax. For example:

<form th:action="@{/register}" th:object="${user}">
  <p>First Name:<input type="text" th:field="*{firstName}" /></p>
  <p>Last Name:<input type="text" th:field="*{lastName}" /></p>
  <p><input type="submit" value="Register" /></p>
</form>

Solution 3: Correcting form binding

Ensure that the form fields are correctly bound to the Java object using the th:field attribute. For example:

<form th:action="@{/register}" th:object="${user}">
  <p>First Name:<input type="text" th:field="*{firstName}" /></p>
  <p>Last Name:<input type="text" th:field="*{lastName}" /></p>
  <p><input type="submit" value="Register" /></p>
</form>

Solution 4: Configuring Spring

Verify that the Spring configuration is correct, including the @EnableWebMvc annotation and the correct view resolver settings. For example:

@Configuration
@EnableWebMvc
public class WebConfig extends WebMvcConfigurerAdapter {
  @Bean
  public ViewResolver viewResolver() {
    ThymeleafViewResolver resolver = new ThymeleafViewResolver();
    resolver.setTemplateEngine(new SpringTemplateEngine());
    resolver.setCharacterEncoding("UTF-8");
    return resolver;
  }
}

Conclusion

And there you have it, folks! By following these troubleshooting steps and implementing the solutions, you should be able to resolve the issue of NULL and blank values NOT showing entered values in your Springboot Thymeleaf form submission. Remember to stay calm, patient, and methodical in your approach, and you’ll be submitting forms like a pro in no time!

If you have any further questions or need more assistance, feel free to ask in the comments below. Happy coding!

Solution	Description
Add getters and setters	Ensure your Java object has proper getters and setters for each form field.
Correct Thymeleaf syntax	Verify that the Thymeleaf template has correct syntax and no typos.
Correct form binding	Ensure that the form fields are correctly bound to the Java object using the th:field attribute.
Configure Spring	Verify that the Spring configuration is correct, including the @EnableWebMvc annotation and the correct view resolver settings.

By following these solutions, you’ll be able to resolve the issue of NULL and blank values NOT showing entered values in your Springboot Thymeleaf form submission. Happy coding!

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