Validating in Spring Boot with Thymeleaf

[Alejandro Barrero]

I am creating a web application in Spring Boot with Thymeleaf and learning how to use validation; I have found several examples In the Internet that work quite well in my computer and have copied code from them. However, running my applicatio, I am getting a page with the message "Whitelabel Error Page";
I also get a very long stack trace in the console; the most important part to me are:

org.thymeleaf.exceptions.TemplateProcessingException: Error during execution of processor 'org.thymeleaf.spring5.processor.SpringInputGeneralFieldTagProcessor' (template: "Admin/GetLicenses" - line 78, col 31)
	at org.thymeleaf.processor.element.AbstractAttributeTagProcessor.doProcess(AbstractAttributeTagProcessor.java:117) ~[thymeleaf-3.0.11.RELEASE.jar:3.0.11.RELEASE]
...
2020-06-06 07:08:41.192 ERROR 10592 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.thymeleaf.exceptions.TemplateProcessingException: Error during execution of 
processor 'org.thymeleaf.spring5.processor.SpringInputGeneralFieldTagProcessor' (template: "Admin/GetLicenses" - line 78, col 31)] with root cause

java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'licensesRequest' available as request attribute

I searched the Internet for problems like "Neither BindingResult nor plain target object for bean name 'licensesRequest' available as request attribute" to no avail.

In tne controller I have:

	@GetMapping("/licenses")
	public String licenses(@RequestParam String fullName, @RequestParam String userName, Model map) {
		map.addAttribute("userName", userName);
		return "Admin/GetLicenses"; // logical view name
	}

	@PostMapping("/fromLicenses")
	public String showLicenses(@Valid @ModelAttribute("licensesRequest") LicensesRequest licensesRequest, BindingResult bindingResult, 
			@RequestParam String userName, Model map) {
		if (bindingResult.hasErrors()) { return "Admin/GetLicenses"; }
...

The application does breack in method "public String licenses" which is called directly from the web page "GetLicenses.html" (showed ahead)", but the problem occurs when the page tries to go to "/fromLicenses" (control method showLicenses).

The important part of GetLicenses.html is:

	<form action="#" th:action="@{/fromLicences(userName=${userName})}" th:object="${licensesRequest}" method="POST">

The more I analyze, I thing that the ideas I have used are correct, although ofcourse I can be wrong; but I am surprised by a part of the message in the stacktrace saying "(template: "Admin/GetLicenses" - line 78, col 31)" because that line corresponds to a part of GetLicenses.html containing:

							<td>Address</td>
							<td><input type="text" th:field="*{address}" /></td>
01234567890123456789012345678901
          1         2         3        
							<td th:if="${#fields.hasErrors('address')}"
								th:errors="*{address}">Address Error</td>
						</tr>

In the bove code I introduced the two lines indicating "line 78, col 31".

The object, LicensesRequest, does have property:

	@NotNull(message="Please enter an address")
	private String address;

I really think that I have provide all the information needed without making this text very long, but i would be glad to provide any further information.

[Tim Nachreiner]

Years ago I saw a Thymeleaf demo that threw the White Label error because an html tag wasn't properly closed.  Thymeleaf is really picky about that.  I see you don't have a closing Form tag.  Try adding one; and also check to make sure every element has a closing tag.

[Himai Minh]

Alejandro,
Do you have getter and setter for the property address?
It seems to me that your address cannot be found in the front end.

[Alejandro Barrero]

Thank you Himai and Tim for your prompt reply; Yes, I have getters and setters; I changed my GetLicenses.html to a form with a simple content with the correction hat Himai indicated:

	<form class="form" th:action="@{/licenses(fullName=${fullName})}" th:object="${licensesRequest}" method="POST">
					<table>
 					<tr>
 						<td>Address:</td>
 						<td><input type="text" th:field="*{address}"></input></td>
 						<td  >Address
 							Error</td>
 					</tr>
 					<tr>
 						<td>City:</td>
 						<td><input type="text" th:field="*{city}"></input></td>
 						<td  >City
 							Error</td>
 					</tr>
 				</table>

My controller is:

	@PostMapping("/licenses")
	public String showLicenses(@Valid LicensesRequest licensesRequest, BindingResult bindingResult, Model map) {
		if (bindingResult.hasErrors()) { return "Admin/GetLicenses"; }
		return "redirect:/BackToAdmin";
	}

Regrettably, I am still getting the "Whitelabel Error Page" message; although without a stack trace.

[Alejandro Barrero]

I discovered something very strange debugging; I found out that the code actually reaches the method @PostMapping showLicenses in the controller. For some reason bindingResult.hasErrors() was giving false and the line of code 'return "redirect:/BackToAdmin";' was being executed and then I would get the error message. I am mystified because from that point on there is no validation; I changed the code to  'return "BackToAdmin";' but I am still having the same problem. I appears I have another problem that I have to investigate.

[Alejandro Barrero]

I still need help with validation; I can live without "redirect:/BackToAdmin"; my problem is that bindingResult.hasErrors() is giving false when there is no date in the web page. The class for the model object is:

package com.model;

import javax.validation.constraints.Max;
import javax.validation.constraints.Min;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Pattern;

public class LicensesRequest {
	@NotNull
	@Min(1)
	@Max(11)
	private Integer numberOfUsers;
	
	@NotNull
	@Pattern(regexp = "^[0-9]{5}$", message="Postal Code is 5 digits")
	private String postalCode;
	
	@NotNull
	@Pattern(regexp = "^[0-9]{3}$", message="CCV is 3 digits")
	private String cCV;
	
	@NotNull(message="Please enter an address")
	private String address;
	
	@NotNull(message="Please enter a city")
	private String city;
	
	@NotNull
	@Pattern(regexp = "^[A-Z]{2}$", message="State is 2 is 2 upper case letters")
	private String state;
	
	@NotNull(message="Please enter your full name")
	private String theFullName;
	
	@NotNull
	@Pattern(regexp = "^[0-9]{4}-[0-9]{4}-[0-9]{4}-[0-9]{4}$", message="CCV is like 7829-3598-7315-0059")
	private String creditCardNumber;
	
	@NotNull
	@Pattern(regexp = "^[0-9]{2}-[0-9]{4}$", message="Expiration is like 05-2020")
	private String expiration;

	public Integer getNumberOfUsers() {
		return numberOfUsers;
	}

	public void setNumberOfUsers(Integer numberOfUsers) {
		this.numberOfUsers = numberOfUsers;
	}

	public String getPostalCode() {
		return postalCode;
	}

	public void setPostalCode(String postalCode) {
		this.postalCode = postalCode;
	}

	public String getcCV() {
		return cCV;
	}

	public void setcCV(String cCV) {
		this.cCV = cCV;
	}

	public String getAddress() {
		return address;
	}

	public void setAddress(String address) {
		this.address = address;
	}

	public String getCity() {
		return city;
	}

	public void setCity(String city) {
		this.city = city;
	}

	public String getState() {
		return state;
	}

	public void setState(String state) {
		this.state = state;
	}

	public String getTheFullName() {
		return theFullName;
	}

	public void setTheFullName(String theFullName) {
		this.theFullName = theFullName;
	}

	public String getCreditCardNumber() {
		return creditCardNumber;
	}

	public void setCreditCardNumber(String creditCardNumber) {
		this.creditCardNumber = creditCardNumber;
	}

	public String getExpiration() {
		return expiration;
	}

	public void setExpiration(String expiration) {
		this.expiration = expiration;
	}
	
}

I should be getting bindingResult.hasErrors() and I should be able to display the errors.

[Alejandro Barrero]

Thanks to all. Well my original problem was solved By TIM; I have a  new problem and I am going to close this one.

[Himai Minh]

Hi, Alejandro,
You may need @RequestBody for the LicenseRequest:

@PostMapping("/licenses")
public String showLicenses( @RequestBody @Valid LicensesRequest licensesRequest, BindingResult bindingResult, Model map) {
    if (bindingResult.hasErrors()) { return "Admin/GetLicenses"; }
    return "redirect:/BackToAdmin";
}

[Alejandro Barrero]

Thank you Himai for your prompt response. Unfortunately I am getting the error message "HTTP Status 415 – Unsupported Media Type".

[Himai Minh]

Hi,
First when is this error coming from? Do you have this dependency in your pom?
<dependency>
           <groupId>org.springframework.boot</groupId>
           <artifactId>spring-boot-starter-thymeleaf</artifactId>
 </dependency>

[Alejandro Barrero]

Yes I have the dependency for spring-boot-starter-thymeleaf and I also have spring-boot-starter-web.