Hibernate validators are very useful and they provide the following annotations that are very helpful for software development.
|
Annotation |
Usages |
|---|---|
| @NotNull | Char Sequence, Collection, Map, or Array object can be validated with this and they should not be null but can be empty |
| @NotEmpty | Char Sequence, Collection, Map, or Array object can be validated with this and they should not be null and not empty |
| @NotBlank | Char Sequence, Collection, Map, or Array objects can be validated with this and they should not be null and not empty and not blank |
| @Min | Given Minimum value has to get satisfied |
| @Max | Given Maximum value has to get satisfied |
| @Size | Field size should be less than or greater than the specified field size |
| Email can be validated with this | |
| @Pattern | Given RegEx Pattern has to be satisfied. |
Let us go with a sample project that includes Hibernate validator.
Example Project
Project Structure:
This is the maven project and hence the required dependencies need to be placed in pom.xml
Mandatory dependency for hibernate validator:
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-validation</artifactId> </dependency>
pom.xml
XML
<?xml version="1.0" encoding="UTF-8"?> xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 <modelVersion>4.0.0</modelVersion> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.4.4</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.gfg.samplehibernatevalidator</groupId> <artifactId>springbootvalidationwithhibernatevalidator</artifactId> <version>v1</version> <properties> <java.version>1.8</java.version> </properties> <dependencies> <!-- Must for hibernate validator--> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-validation</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <!-- dependency for automatic reloads or live reload of applications --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-devtools</artifactId> <scope>runtime</scope> <optional>true</optional> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build></project> |
Let us start with a bean class that can have the annotations
GeekEmployee.java
Java
import javax.validation.constraints.Email;import javax.validation.constraints.Max;import javax.validation.constraints.Min;import javax.validation.constraints.NotBlank;import javax.validation.constraints.NotNull;import javax.validation.constraints.Size;public class GeekEmployee { @NotBlank(message = "Please enter proper employee name") @Size(min=5, message = "Name should be atleast 5 characters") @Size(max=12, message = "Name should not be greater than 12 characters") private String geekEmployeeName; @NotNull(message = "Please enter a valid salary") @Min(value=1000, message = "Salary must be atleast 1000.00") @Max(value=40000, message = "Salary should not be greater than 40000.00") private Double salary; @Email(message = "Please enter a valid email Id", regexp="^[a-zA-Z0-9._-]+@[a-zA-Z0-9-]+\\.[a-zA-Z.]{2,5}") @NotNull(message = "Please enter a valid email Id") private String geekEmailId; @NotBlank(message = "Please enter qualifications") @NotNull(message = "Please enter qualifications") private String qualifications; public String getQualifications() { return qualifications; } public void setQualifications(String qualifications) { this.qualifications = qualifications; } public String getGeekEmployeeName() { return geekEmployeeName; } public void setGeekEmployeeName(String geekEmployeeName) { this.geekEmployeeName = geekEmployeeName; } public Double getSalary() { return salary; } public void setSalary(Double salary) { this.salary = salary; } public String getGeekEmailId() { return geekEmailId; } public void setGeekEmailId(String geekEmailId) { this.geekEmailId = geekEmailId; } } |
To collect all the errors, we need to have an “ExceptionHandler” and it is given below
ExceptionHandler.java
Java
import java.util.Date;import java.util.LinkedHashMap;import java.util.List;import java.util.Map;import java.util.stream.Collectors;import org.springframework.http.HttpHeaders;import org.springframework.http.HttpStatus;import org.springframework.http.ResponseEntity;import org.springframework.web.bind.MethodArgumentNotValidException;import org.springframework.web.bind.annotation.ControllerAdvice;import org.springframework.web.context.request.WebRequest;import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler;@ControllerAdvicepublic class ExceptionHandler extends ResponseEntityExceptionHandler{ @Override protected ResponseEntity<Object> handleMethodArgumentNotValid(MethodArgumentNotValidException exception, HttpHeaders httpHeaders, HttpStatus httpStatus, WebRequest webRequest) { Map<String, Object> objectBody = new LinkedHashMap<>(); objectBody.put("Current Timestamp", new Date()); objectBody.put("Status", httpStatus.value()); // Get all errors List<String> exceptionalErrors = exception.getBindingResult() .getFieldErrors() .stream() .map(x -> x.getDefaultMessage()) .collect(Collectors.toList()); objectBody.put("Errors", exceptionalErrors); return new ResponseEntity<>(objectBody, httpStatus); }} |
Let us try to save the geekemployees by accepting the inputs like “geekEmployeeName”,”salary”,”geekEmailId” and “qualifications”. We need a rest controller file to achieve the same.
GeekEmplooyeeController.java
Java
import javax.validation.Valid;import org.springframework.http.HttpStatus;import org.springframework.http.ResponseEntity;import org.springframework.web.bind.annotation.PostMapping;import org.springframework.web.bind.annotation.RequestBody;import org.springframework.web.bind.annotation.RestController;@RestControllerpublic class GeekEmplooyeeController { @PostMapping("/geekemployees") public ResponseEntity<GeekEmployee> saveEmployeeData (@Valid @RequestBody GeekEmployee geekEmployee) { return new ResponseEntity<GeekEmployee>(geekEmployee, HttpStatus.CREATED); }} |
Our last step is to write the main class that starts the spring boot project. Via eclipse also it can be started as an ordinary java application or since it is a maven application, it can be started as
mvn spring-boot:run
ValidationApplication.java
Java
import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplicationpublic class ValidationApplication { public static void main(String[] args) { SpringApplication.run(ValidationApplication.class, args); }} |
On running the application, in the console, we can see as follows
Let’s check the working part by using the postman client as we are using post mapping
Conclusion
By means of Hibernate validator, very easily front-end validations can be checked and that helps a lot in spring boot projects simply a dependency makes these kinds of validations to validate a page.
