In our last example we saw how to do field validation declaratively using bean validation API.
We can simplify our code a little more on the view side by using Spring Form JSP Tag Library.
Among many things, Spring Tag Library provides JSP tags to render validation errors implicitly via errors tag.
Let's modify our last example one more time to see how that works.
user-registration.jsp
src/main/webapp/WEB-INF/views/user-registration.jsp<%@taglib uri="http://www.springframework.org/tags/form" prefix="frm" %>
<html>
<head>
<style>
span.error {
color: red;
}
</style>
</head>
<body style="padding: 10px">
<h3> Registration Form
<h3>
<br/>
<frm:form action="register" method="post" modelAttribute="user">
Name
<frm:input path="name"/>
<br/>
<frm:errors path="name" cssClass="error"/>
<br/><br/>
Email address
<frm:input path="emailAddress"/>
<br/>
<frm:errors path="emailAddress" cssClass="error"/>
<br/><br/>
Password
<frm:password path="password"/>
<br/>
<frm:errors path="password" cssClass="error"/>
<br/><br/>
<input type="submit" value="Submit"/>
</frm:form>
</body>
</html>
In above code, spring form tag is implicitly mapping the backing object fields to the HTML form fields and also taking care of the validation errors via frm:errors.
One more important thing to understand is that, Spring top level form tag must have to specify 'modelAttribute' which is actually the name of the 'model attribute' under which the form object is exposed. That also means we are required to use annotation @ModelAttribute on our backing object using the same name as 'modelAttribute'. Please see our controller next.
The Controller
Comparing with our last example our controller has become simpler, now we don't have to populate error messages in model.
package com.logicbig.example;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import jakarta.validation.Valid;
@Controller
@RequestMapping("/register")
public class UserRegistrationController {
@Autowired private UserService userService;
@GetMapping
public String handleGetRequest(Model model) {
model.addAttribute("user", new User());
return "user-registration";
}
@PostMapping
public String handlePostRequest(
@Valid @ModelAttribute("user") User user, BindingResult bindingResult, Model model) {
if (bindingResult.hasErrors()) {
return "user-registration";
}
userService.saveUser(user);
return "registration-done";
}
}
Notice, in above handler method we must use @ModelAttribute with a name matching with 'modelAttribute' in our jsp form.
Running Example
To try examples, run embedded Jetty (configured in pom.xml of example project below):
mvn jetty:run
$ curl -s http://localhost:8080/spring-form-tag-lib/register -d "name=Joe&emailAddress=joe@example.com&password=abc"
<html>
<head>
<style>
span.error {
color: red;
}
</style>
</head>
<body style="padding: 10px">
<h3> Registration Form
<h3>
<br/>
<form id="user" action="register" method="post">
Name
<input id="name" name="name" type="text" value="Joe"/>
<br/>
<span id="name.errors" class="error">size must be between 5 and 20</span>
<br/><br/>
Email address
<input id="emailAddress" name="emailAddress" type="text" value="joe@example.com"/>
<br/>
<br/><br/>
Password
<input id="password" name="password" type="password" value=""/>
<br/>
<span id="password.errors" class="error">size must be between 6 and 15</span>
<br/><br/>
<input type="submit" value="Submit"/>
</form>
</body>
</html>
http://localhost:8080/spring-form-tag-lib/register
Integration Tests
package com.logicbig.example;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.ExtendWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit.jupiter.SpringExtension;
import org.springframework.test.context.web.WebAppConfiguration;
import org.springframework.test.web.servlet.assertj.MockMvcTester;
import org.springframework.test.web.servlet.assertj.MvcTestResult;
import org.springframework.validation.BindingResult;
import org.springframework.validation.FieldError;
import org.springframework.web.context.WebApplicationContext;
import static org.assertj.core.api.Assertions.assertThat;
@ExtendWith(SpringExtension.class)
@WebAppConfiguration
@ContextConfiguration(classes = MyWebConfig.class)
public class RegistrationControllerTest {
@Autowired
private WebApplicationContext wac;
@Autowired
private UserService userService;
private MockMvcTester mockMvc;
@BeforeEach
void setup() {
this.mockMvc = MockMvcTester.from(this.wac);
}
@Test
void testRegistrationSuccess() {
MvcTestResult result =
mockMvc.post().uri("/register")
.param("name", "Joseph")
.param("emailAddress", "joe@email.address")
.param("password", "abcdef")
.exchange();
assertThat(result)
.hasStatusOk()
.hasViewName("registration-done");
assertThat(result).model()
.doesNotHaveErrors()
.containsKey("user");
assertThat(result.getMvcResult().getModelAndView().getModel()
.get("user"))
.isInstanceOfSatisfying(User.class, user -> {
assertThat(user.getName()).isEqualTo("Joseph");
assertThat(user.getEmailAddress()).isEqualTo(
"joe@email.address");
});
User saved = userService.getUserById(1L);
assertThat(saved).isNotNull();
assertThat(saved.getName()).isEqualTo("Joseph");
assertThat(saved.getEmailAddress()).isEqualTo("joe@email.address");
assertThat(saved.getPassword()).isEqualTo("abcdef");
}
@Test
void testRegistrationFailure_EmptyName() {
MvcTestResult result =
mockMvc.post().uri("/register")
.param("name", "")
.param("emailAddress",
"joe@email.address")
.param("password", "abcdef")
.exchange();
assertThat(result)
.hasStatusOk()
.hasViewName("user-registration");
assertThat(result).model()
.hasErrors()
.hasAttributeErrors("user");
assertThat(result).model()
.extractingBindingResult("user")
.hasErrorsCount(1)
.hasOnlyFieldErrors("name");
assertThat(extractBindingResult(result, "user")
.getFieldError("name")
.getDefaultMessage())
.isEqualTo("size must be between 5 and 20");
}
@Test
void testRegistrationFailure_InvalidEmail() {
MvcTestResult result =
mockMvc.post().uri("/register")
.param("name", "Joseph")
.param("emailAddress", "invalid-email")
.param("password", "abcdef")
.exchange();
assertThat(result)
.hasStatusOk()
.hasViewName("user-registration");
assertThat(result).model()
.hasErrors()
.hasAttributeErrors("user");
assertThat(result).model()
.extractingBindingResult("user")
.hasErrorsCount(1)
.hasOnlyFieldErrors("emailAddress");
assertThat(extractBindingResult(result, "user")
.getFieldError("emailAddress")
.getDefaultMessage())
.isEqualTo("Email is not valid");
}
@Test
void testRegistrationFailure_EmptyPassword() {
MvcTestResult result =
mockMvc.post().uri("/register")
.param("name", "Joseph")
.param("emailAddress",
"joe@email.address")
.param("password", "")
.exchange();
assertThat(result)
.hasStatusOk()
.hasViewName("user-registration");
assertThat(result).model()
.hasErrors()
.hasAttributeErrors("user");
assertThat(result).model()
.extractingBindingResult("user")
.hasErrorsCount(2)
.hasOnlyFieldErrors("password");
assertThat(extractBindingResult(result, "user").getFieldErrors(
"password"))
.hasSize(2)
.extracting(FieldError::getDefaultMessage)
.satisfiesExactlyInAnyOrder(
msg -> assertThat(msg).contains("Spaces are not allowed"),
msg -> assertThat(msg).contains(
"size must be between 6 and 15")
);
}
// --- helper ---
private BindingResult extractBindingResult(MvcTestResult result,
String attrName) {
return (BindingResult) result.getMvcResult()
.getModelAndView()
.getModel()
.get(BindingResult.MODEL_KEY_PREFIX + attrName);
}
}
mvn clean test -Dtest="RegistrationControllerTest" Output$ mvn clean test -Dtest="RegistrationControllerTest"
[INFO] Scanning for projects...
[INFO]
[INFO] --------------< com.logicbig.example:spring-form-tag-lib >--------------
[INFO] Building spring-form-tag-lib 1.0-SNAPSHOT
[INFO] from pom.xml
[INFO] --------------------------------[ war ]---------------------------------
[INFO]
[INFO] --- clean:3.2.0:clean (default-clean) @ spring-form-tag-lib ---
[INFO] Deleting D:\example-projects\spring-mvc\spring-form-tag-lib\target
[INFO]
[INFO] --- resources:3.3.1:resources (default-resources) @ spring-form-tag-lib ---
[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!
[INFO] skip non existing resourceDirectory D:\example-projects\spring-mvc\spring-form-tag-lib\src\main\resources
[INFO]
[INFO] --- compiler:3.15.0:compile (default-compile) @ spring-form-tag-lib ---
[INFO] Recompiling the module because of changed source code.
[INFO] Compiling 6 source files with javac [debug target 25] to target\classes
[INFO]
[INFO] --- resources:3.3.1:testResources (default-testResources) @ spring-form-tag-lib ---
[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!
[INFO] skip non existing resourceDirectory D:\example-projects\spring-mvc\spring-form-tag-lib\src\test\resources
[INFO]
[INFO] --- compiler:3.15.0:testCompile (default-testCompile) @ spring-form-tag-lib ---
[INFO] Recompiling the module because of changed dependency.
[INFO] Compiling 2 source files with javac [debug target 25] to target\test-classes
[INFO]
[INFO] --- surefire:3.2.5:test (default-test) @ spring-form-tag-lib ---
[INFO] Using auto detected provider org.apache.maven.surefire.junitplatform.JUnitPlatformProvider
[WARNING] file.encoding cannot be set as system property, use <argLine>-Dfile.encoding=...</argLine> instead
[INFO]
[INFO] -------------------------------------------------------
[INFO] T E S T S
[INFO] -------------------------------------------------------
[INFO] Running com.logicbig.example.RegistrationControllerTest
[INFO] Tests run: 4, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 1.294 s -- in com.logicbig.example.RegistrationControllerTest
[INFO]
[INFO] Results:
[INFO]
[INFO] Tests run: 4, Failures: 0, Errors: 0, Skipped: 0
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 4.698 s
[INFO] Finished at: 2026-04-15T11:39:13+08:00
[INFO] ------------------------------------------------------------------------
Apr 15, 2026 11:39:12 AM org.hibernate.validator.internal.util.Version <clinit>
INFO: HV000001: Hibernate Validator 9.0.1.Final
INFO: Completed initialization in 2 ms
INFO: Completed initialization in 1 ms
INFO: Completed initialization in 1 ms
INFO: Completed initialization in 0 ms
Example ProjectDependencies and Technologies Used: - spring-webmvc 7.0.6 (Spring Web MVC)
Version Compatibility: 3.2.9.RELEASE - 7.0.6 Version compatibilities of spring-webmvc with this example: Versions in green have been tested.
- spring-test 7.0.6 (Spring TestContext Framework)
- jakarta.servlet-api 6.1.0 (Jakarta Servlet API documentation)
- hibernate-validator 9.0.1.Final (Hibernate's Jakarta Validation reference implementation)
- jakarta.el 4.0.0 (Jakarta Expression Language Implementation)
- junit-jupiter-engine 6.0.3 (Module "junit-jupiter-engine" of JUnit)
- hamcrest 3.0 (Core API and libraries of hamcrest matcher framework)
- assertj-core 3.26.3 (Rich and fluent assertions for testing in Java)
- JDK 25
- Maven 3.9.11
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