No @NotBlank validator for type String

Question

I keep getting validator error for quite simple configuration class

import lombok.Data;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;
import org.springframework.validation.annotation.Validated;

import javax.validation.constraints.NotBlank;

@Component
@Data
@Validated
@ConfigurationProperties(prefix = "test")
public class TestProperties {
    @NotBlank
    String uri;
}

Error is self explaining:

javax.validation.UnexpectedTypeException: HV000030: No validator could be found for constraint 'javax.validation.constraints.NotBlank' validating type 'java.lang.String'. Check configuration for 'uri'

But according to spring boot documentation this should work.

Firstrate

It turns out Spring Boot uses Hibernate validator to make things work. I tries to use Bean Validation 2 annotations with Hibernate 5. Which obviously didn't work. – Firstrate

you're a life saver! spring-boot-starter-web 1.5.8 was using hibernate-validator 5.x.x. So I just added an exclusion to that dependency and fixed my issue. You should make an answer and mark it! – Celebrant

Answer 1

I had the same issue and solved it.

As Yogi stated in his answer, there are two implementations:

import javax.validation.constraints.NotBlank;

and

import org.hibernate.validator.constraints.NotBlank;

Switching from the javax implementation to the hibernate one solved the issue.

Since I didn't use Spring boot, I had to add to my pom.xml:

<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-validator</artifactId>
    <version>5.2.4.Final</version>
</dependency>

Burgomaster

import org.hibernate.validator.constraints.NotBlank; is depricated – Springfield

Answer 2

According to Spring-Boot documentation and maven central repo the:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

has the validator included. If you have not spring-boot-starter-web included to your dependencies you can just add the validator:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-validation</artifactId>
</dependency>

Cochineal

Answer 3

I saw a similar question outside this forum and discovered that the error comes up whenever you try to put @NotBlank annotation on any non-string type field. In my case, the javax.validation.UnexpectedTypeException came up when I annotated a field of type Byte with @NotBlank. So I imported javax.validation.constraints.NotNull, changed the annotation on the Byte field to @NotNull and the error disappeared.

I previously tried replacing import javax.validation.constraints.NotBlank; with import org.hibernate.validator.constraints.NotBlank; to kill the error, but I got a deprecation warning. Programmers are discouraged from using deprecated program elements, so I advise that you use @NotNull annotation instead.

To understand the differences between @NotBlank and @NotNull, see this StackOverflow thread. That way, you get to decide if @NotNull fits your use case.

Coccid

Answer 4

In my case, it worked okay when running as a standalone application, but gave this same error when running as a WAR; in order to make it work, it was necessary to explicitly import the hibernate-validator as a dependency in order to make it work when running as a WAR:

<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-validator</artifactId>
    <version>7.0.2.Final</version>
</dependency>
<dependency>
    <groupId>org.hibernate.validator</groupId>
    <artifactId>hibernate-validator-annotation-processor</artifactId>
</dependency>

Arcograph

Answer 5

You can use below options,which works with Spring JPA:

1. org.hibernate.validator.constraints.NotBlank
2. javax.validation.constraints.NotNull

Nickeliferous

Answer 6

I have always used @NotNull.

I think the corresponding POM code is

<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency>

Wrecker

That's not what he was asking about. @NotNull and @NotBlank have different semantics for Strings – Unreality