Validating RequestParams and PathVariables in Spring

Last updated: February 4, 2026

Written by: baeldung

Reviewed by: Tom Hombergs

Spring MVC

Refactor Java code safely — and automatically — with OpenRewrite.

Refactoring big codebases by hand is slow, risky, and easy to put off. That’s where OpenRewrite comes in. The open-source framework for large-scale, automated code transformations helps teams modernize safely and consistently.

Each month, the creators and maintainers of OpenRewrite at Moderne run live, hands-on training sessions — one for newcomers and one for experienced users. You’ll see how recipes work, how to apply them across projects, and how to modernize code with confidence.

Join the next session, bring your questions, and learn how to automate the kind of work that usually eats your sprint time.

Distributed systems often come with complex challenges such as service-to-service communication, state management, asynchronous messaging, security, and more.

Dapr (Distributed Application Runtime) provides a set of APIs and building blocks to address these challenges, abstracting away infrastructure so we can focus on business logic.

In this tutorial, we'll focus on Dapr's pub/sub API for message brokering. Using its Spring Boot integration, we'll simplify the creation of a loosely coupled, portable, and easily testable pub/sub messaging system:

>> Flexible Pub/Sub Messaging With Spring Boot and Dapr

1. Introduction

In this tutorial, we’ll learn how to validate HTTP request parameters and path variables in Spring MVC.

Specifically, we’ll validate String and Number parameters with JSR 303 annotations.

To explore the validation of other types, we can refer to our tutorials about Java Bean Validation and method constraints, or we can learn how to create our own validator.

2. Configuration

To use the Java Validation API, we have to add a JSR 303 implementation, such as hibernate-validator:

<dependency>
    <groupId>org.hibernate.validator</groupId>
    <artifactId>hibernate-validator</artifactId>
    <version>8.0.1.Final</version>
</dependency>

We also have to enable validation for both request parameters and path variables in our controllers by adding the @Validated annotation:

@RestController
@RequestMapping("/")
@Validated
public class RequestAndPathVariableValidationController {
    // ...
}

It’s important to note that enabling parameter validation also requires a MethodValidationPostProcessor bean. If we’re using a Spring Boot application, then this bean is auto-configured, as we have the hibernate-validator dependency on our classpath.

Otherwise, in a standard Spring application, we have to add this bean explicitly:

@EnableWebMvc
@Configuration
@ComponentScan("com.baeldung.spring")
public class ClientWebConfigJava implements WebMvcConfigurer {
    @Bean
    public MethodValidationPostProcessor methodValidationPostProcessor() {
        return new MethodValidationPostProcessor();
    }
    // ...
}

By default, any error during path or request validation in Spring results in an HTTP 500 response. In this tutorial, we’ll use a custom implementation of ControllerAdvice to handle these kinds of errors in a more readable way, returning an HTTP 400 for any bad request. We can find the source code of this solution at GitHub.

3. Validating a RequestParam

Let’s consider an example where we pass a numeric weekday into a controller method as a request parameter:

@GetMapping("/name-for-day")
public String getNameOfDayByNumberRequestParam(@RequestParam Integer dayOfWeek) {
    // ...
}

Our goal is to make sure that the value of dayOfWeek is between 1 and 7. To do so, we’ll use the @Min and @Max annotations:

@GetMapping("/name-for-day")
public String getNameOfDayByNumberRequestParam(@RequestParam @Min(1) @Max(7) Integer dayOfWeek) {
    // ...
}

Any request that doesn’t match these conditions will return an HTTP status 400 with a default error message.

If we call http://localhost:8080/name-for-day?dayOfWeek=24, for instance, the response message will be:

getNameOfDayByNumber.dayOfWeek: must be less than or equal to 7

We can change the default message by adding a custom one:

@Max(value = 1, message = “day number has to be less than or equal to 7”)

4. Validating a PathVariable

Just as with @RequestParam, we can use any annotation from the jakarta.validation.constraints package to validate a @PathVariable.

Let’s consider an example where we validate that a String parameter isn’t blank and has a length of less than or equal to 10:

@GetMapping("/valid-name/{name}")
public void validStringRequestParam(@PathVariable("name") @NotBlank @Size(max = 10) String username) {
    // ...
}

Any request with a name parameter longer than 10 characters, for instance, will result in an HTTP 400 error with a message:

createUser.name:size must be between 0 and 10

The default message can be easily overwritten by setting the message parameter in the @Size annotation.

5. Conclusion

In this article, we learned how to validate request parameters and path variables in Spring applications.

The code backing this article is available on GitHub. Once you're logged in as a Baeldung Pro Member, start learning and coding on the project.

REST with Spring Boot

Learn Spring Security

Learn Spring

Learn Spring Data JPA

View All Spring Courses

Learn JUnit

Learn Maven

Learn Hibernate JPA

Learn Mockito

View All Courses

Full Archive

Baeldung Ebooks

About Baeldung

1. Introduction

2. Configuration

3. Validating a RequestParam

4. Validating a PathVariable

5. Conclusion