In this
post, I am going to explain how to build simple query builder using jpa
specification.
As shown
in above figure, client submits a query using json payload, application
understands this query string and raises corresponding JPA query.
Example
1: Equal check query filter
Query
String
{
"searchFitler": [
{
"operator": "=",
"property":
"firstName",
"value": "Ram"
}
]
}
SQL Query
select *
from my_employee e where e.first_name='Ram'
Example
2: Conunction of two or more properties
{
"searchFitler": [
{
"operator": "=",
"property": "age",
"value": "32"
},
{
"operator": "LIKE",
"property":
"lastName",
"value": "rram"
}
]
}
Example
3: IN Query
{
"searchFitler": [
{
"operator": "IN",
"property": "age",
"value": [43, 39]
}
]
}
It is
pretty simple, create a specification that takes a search query and give the
predicates.
public class SpecificationUtil {
public static <T> Specification<T> bySearchQuery(SearchQuery searchQuery, Class<T> clazz) {
return (Root<T> root, CriteriaQuery<?> query, CriteriaBuilder criterailBuilder) -> {
List<Predicate> predicates = new ArrayList<>();
List<SearchFilter> searchFilters = searchQuery.getSearchFitler();
if (searchFilters == null || searchFilters.isEmpty()) {
return null;
}
for (final SearchFilter searchFilter : searchFilters) {
String property = searchFilter.getProperty();
Path expression = root.get(property);
switch (searchFilter.getOperator()) {
case "=":
predicates.add(criterailBuilder.equal(expression, searchFilter.getValue()));
break;
case "LIKE":
predicates.add(criterailBuilder.like(expression, "%" + searchFilter.getValue() + "%"));
break;
case "IN":
predicates.add(criterailBuilder.in(expression).value(searchFilter.getValue()));
break;
case ">":
predicates.add(criterailBuilder.greaterThan(expression, (Comparable) searchFilter.getValue()));
break;
case "<":
predicates.add(criterailBuilder.lessThan(expression, (Comparable) searchFilter.getValue()));
break;
case ">=":
predicates.add(
criterailBuilder.greaterThanOrEqualTo(expression, (Comparable) searchFilter.getValue()));
break;
case "<=":
predicates
.add(criterailBuilder.lessThanOrEqualTo(expression, (Comparable) searchFilter.getValue()));
break;
case "!":
predicates.add(criterailBuilder.notEqual(expression, searchFilter.getValue()));
break;
case "IsNull":
predicates.add(criterailBuilder.isNull(expression));
break;
case "NotNull":
predicates.add(criterailBuilder.isNotNull(expression));
break;
default:
System.out.println("Predicate is not matched");
throw new IllegalArgumentException(searchFilter.getOperator() + " is not a valid predicate");
}
}
if (predicates.isEmpty()) {
return criterailBuilder.conjunction();
}
return criterailBuilder.and(predicates.toArray(new Predicate[0]));
};
}
}
Find the
below working example.
Employee.java
package com.sample.app.model;
import java.util.Date;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.EntityListeners;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
import org.springframework.data.annotation.CreatedBy;
import org.springframework.data.annotation.CreatedDate;
import org.springframework.data.annotation.LastModifiedBy;
import org.springframework.data.annotation.LastModifiedDate;
import org.springframework.data.jpa.domain.support.AuditingEntityListener;
@Entity
@Table(name = "my_employee")
@EntityListeners(AuditingEntityListener.class)
public class Employee {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Integer id;
@Column(name = "first_name")
private String firstName;
@Column(name = "last_name")
private String lastName;
@Column(name = "age")
private Integer age;
@Column(name = "salary")
private Double salary;
@CreatedDate
@Column(name = "created_date")
private Date createdTime;
@LastModifiedDate
@Column(name = "last_modified_date")
private Date lastModifiedTime;
@CreatedBy
private String createdBy;
@LastModifiedBy
private String modifiedBy;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public Double getSalary() {
return salary;
}
public void setSalary(Double salary) {
this.salary = salary;
}
public static EmployeeBuilder builder() {
return new EmployeeBuilder();
}
public Date getCreatedTime() {
return createdTime;
}
public void setCreatedTime(Date createdTime) {
this.createdTime = createdTime;
}
public Date getLastModifiedTime() {
return lastModifiedTime;
}
public void setLastModifiedTime(Date lastModifiedTime) {
this.lastModifiedTime = lastModifiedTime;
}
public static class EmployeeBuilder {
private Employee emp;
public EmployeeBuilder() {
emp = new Employee();
}
public EmployeeBuilder firstName(String firstName) {
emp.setFirstName(firstName);
return this;
}
public EmployeeBuilder lastName(String lastName) {
emp.setLastName(lastName);
return this;
}
public EmployeeBuilder age(int age) {
emp.setAge(age);
return this;
}
public EmployeeBuilder salary(double salary) {
emp.setSalary(salary);
return this;
}
public Employee build() {
return emp;
}
}
public String getCreatedBy() {
return createdBy;
}
public void setCreatedBy(String createdBy) {
this.createdBy = createdBy;
}
public String getModifiedBy() {
return modifiedBy;
}
public void setModifiedBy(String modifiedBy) {
this.modifiedBy = modifiedBy;
}
@Override
public String toString() {
StringBuilder builder = new StringBuilder();
builder.append("Employee [id=").append(id).append(", firstName=").append(firstName).append(", lastName=")
.append(lastName).append(", age=").append(age).append(", salary=").append(salary)
.append(", createdTime=").append(createdTime).append(", lastModifiedTime=").append(lastModifiedTime)
.append(", createdBy=").append(createdBy).append(", modifiedBy=").append(modifiedBy).append("]");
return builder.toString();
}
}
SearchFilter.java
package com.sample.app.model;
public class SearchFilter {
private String property;
private String operator;
private Object value;
public String getProperty() {
return property;
}
public void setProperty(String property) {
this.property = property;
}
public String getOperator() {
return operator;
}
public void setOperator(String operator) {
this.operator = operator;
}
public Object getValue() {
return value;
}
public void setValue(Object value) {
this.value = value;
}
}
SearchQuery.java
package com.sample.app.model;
import java.util.List;
public class SearchQuery {
private List<SearchFilter> searchFitler;
public List<SearchFilter> getSearchFitler() {
return searchFitler;
}
public void setSearchFitler(List<SearchFilter> searchFitler) {
this.searchFitler = searchFitler;
}
}
EmployeeRepository.java
package com.sample.app.repository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.springframework.data.repository.PagingAndSortingRepository;
import com.sample.app.model.Employee;
public interface EmployeeRepository extends JpaSpecificationExecutor<Employee>, PagingAndSortingRepository<Employee, Integer>{
}
SpeicificationUtil.java
package com.smaple.app.jpa.specification;
import java.util.ArrayList;
import java.util.List;
import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Path;
import javax.persistence.criteria.Predicate;
import javax.persistence.criteria.Root;
import org.springframework.data.jpa.domain.Specification;
import com.sample.app.model.SearchFilter;
import com.sample.app.model.SearchQuery;
public class SpecificationUtil {
public static <T> Specification<T> bySearchQuery(SearchQuery searchQuery, Class<T> clazz) {
return (Root<T> root, CriteriaQuery<?> query, CriteriaBuilder criterailBuilder) -> {
List<Predicate> predicates = new ArrayList<>();
List<SearchFilter> searchFilters = searchQuery.getSearchFitler();
if (searchFilters == null || searchFilters.isEmpty()) {
return null;
}
for (final SearchFilter searchFilter : searchFilters) {
String property = searchFilter.getProperty();
Path expression = root.get(property);
switch (searchFilter.getOperator()) {
case "=":
predicates.add(criterailBuilder.equal(expression, searchFilter.getValue()));
break;
case "LIKE":
predicates.add(criterailBuilder.like(expression, "%" + searchFilter.getValue() + "%"));
break;
case "IN":
predicates.add(criterailBuilder.in(expression).value(searchFilter.getValue()));
break;
case ">":
predicates.add(criterailBuilder.greaterThan(expression, (Comparable) searchFilter.getValue()));
break;
case "<":
predicates.add(criterailBuilder.lessThan(expression, (Comparable) searchFilter.getValue()));
break;
case ">=":
predicates.add(
criterailBuilder.greaterThanOrEqualTo(expression, (Comparable) searchFilter.getValue()));
break;
case "<=":
predicates
.add(criterailBuilder.lessThanOrEqualTo(expression, (Comparable) searchFilter.getValue()));
break;
case "!":
predicates.add(criterailBuilder.notEqual(expression, searchFilter.getValue()));
break;
case "IsNull":
predicates.add(criterailBuilder.isNull(expression));
break;
case "NotNull":
predicates.add(criterailBuilder.isNotNull(expression));
break;
default:
System.out.println("Predicate is not matched");
throw new IllegalArgumentException(searchFilter.getOperator() + " is not a valid predicate");
}
}
if (predicates.isEmpty()) {
return criterailBuilder.conjunction();
}
return criterailBuilder.and(predicates.toArray(new Predicate[0]));
};
}
}
EmployeeController.java
package com.sample.app.controller;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
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;
import com.sample.app.model.Employee;
import com.sample.app.model.SearchQuery;
import com.sample.app.repository.EmployeeRepository;
import com.smaple.app.jpa.specification.SpecificationUtil;
import io.swagger.annotations.ApiOperation;
@RestController
public class EmployeeController {
@Autowired
private EmployeeRepository empRepo;
@ApiOperation(value = "Employees Filter", notes = "Get employees by search criteria")
@PostMapping(value = "/employees", produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<List<Employee>> getEmployees(@RequestBody SearchQuery searchQuery) {
List<Employee> emps = empRepo.findAll(SpecificationUtil.bySearchQuery(searchQuery, Employee.class));
return new ResponseEntity<>(emps, HttpStatus.OK);
}
}
SwaggerConfig.java
package com.sample.app.config;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Component;
import springfox.documentation.builders.ApiInfoBuilder;
import springfox.documentation.builders.PathSelectors;
import springfox.documentation.builders.RequestHandlerSelectors;
import springfox.documentation.service.ApiInfo;
import springfox.documentation.spi.DocumentationType;
import springfox.documentation.spring.web.plugins.Docket;
import springfox.documentation.swagger2.annotations.EnableSwagger2;
@Component
@EnableAutoConfiguration
@EnableSwagger2
public class SwaggerConfig {
@Bean
public Docket userApi() {
return new Docket(DocumentationType.SWAGGER_2).apiInfo(apiInfo()).select().paths(PathSelectors.any())
.apis(RequestHandlerSelectors.basePackage("com.sample.app.controller")).build();
}
private ApiInfo apiInfo() {
return new ApiInfoBuilder().title("Query builder").description("Query builder using spring specification")
.version("2.0").build();
}
}
App.java
package com.sample.app;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import com.sample.app.model.Employee;
import com.sample.app.repository.EmployeeRepository;
@SpringBootApplication
public class App {
public static void main(String args[]) {
SpringApplication.run(App.class, args);
}
@Bean
public CommandLineRunner demo(EmployeeRepository employeeRepository) {
return (args) -> {
Employee emp1 = Employee.builder().firstName("Ram").lastName("Gurram").age(32).salary(100000.23).build();
Employee emp2 = Employee.builder().firstName("Joel").lastName("Chelli").age(43).salary(60000).build();
Employee emp3 = Employee.builder().firstName("Gopi").lastName("Battu").age(32).salary(1000000).build();
Employee emp4 = Employee.builder().firstName("Bomma").lastName("Srikanth").age(39).salary(60000).build();
Employee emp5 = Employee.builder().firstName("Surendra").lastName("Gurram").age(32).salary(100000.23).build();
Employee emp6 = Employee.builder().firstName("Bhadri").lastName("Venakata RamaRao").age(32)
.salary(100000.23).build();
Employee emp7 = Employee.builder().firstName("Sushmithaa").lastName("Kulakarni").age(39).salary(100000.23)
.build();
employeeRepository.save(emp1);
employeeRepository.save(emp2);
employeeRepository.save(emp3);
employeeRepository.save(emp4);
employeeRepository.save(emp5);
employeeRepository.save(emp6);
employeeRepository.save(emp7);
for (Employee emp : employeeRepository.findAll()) {
System.out.println(emp);
}
};
}
}
application.properties
logging.level.root=WARN logging.level.org.hibernate=ERROR ## H2 specific properties spring.h2.console.enabled=true spring.h2.console.path=/h2 spring.datasource.url=jdbc:h2:file:~/db/myOrg.db;DB_CLOSE_ON_EXIT=FALSE;DB_CLOSE_DELAY=-1; spring.datasource.username=krishna spring.datasource.password=password123 spring.datasource.driverClassName=org.h2.Driver ## JPA specific properties # Creates the schema, destroying previous data. spring.jpa.hibernate.ddl-auto=create spring.jpa.database-platform=org.hibernate.dialect.H2Dialect spring.jpa.show-sql=true #spring.jpa.properties.hibernate.format_sql=true ## Database connection pooling properties # Number of ms to wait before throwing an exception if no connection is available. spring.datasource.max-wait=10000 # Maximum number of active connections that can be allocated from this pool at the same time. spring.datasource.tomcat.max-active=10 spring.datasource.tomcat.max-idle=5 spring.datasource.tomcat.min-idle=3
pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>springDataSpecification</groupId>
<artifactId>springDataSpecification</artifactId>
<version>1</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.6.RELEASE</version>
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-data-jpa -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<!-- https://mvnrepository.com/artifact/com.h2database/h2 -->
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>io.springfox</groupId>
<artifactId>springfox-swagger2</artifactId>
<version>2.9.2</version>
</dependency>
<dependency>
<groupId>io.springfox</groupId>
<artifactId>springfox-swagger-ui</artifactId>
<version>2.9.2</version>
</dependency>
</dependencies>
</project>
Total
project structure looks like below.
Run
App.java.
Open the
url ‘http://localhost:8080/swagger-ui.html’ in browser.
Click on
> (arrow) against employee-controller.
Click on POST
button.
Click on ‘Try
it out’ button.
Under searchQuery
section, give the post body as below.
{
"searchFitler": [
{
"operator": "=",
"property":
"firstName",
"value": "Ram"
}
]
}
Click on Execute
button. You will get below response.
[
{
"id": 1,
"firstName": "Ram",
"lastName": "Gurram",
"age": 32,
"salary": 100000.23,
"createdTime": null,
"lastModifiedTime": null,
"createdBy": null,
"modifiedBy": null
}
]
You can download
complete working application from this link.
Use below snippet to add to support not in query.
ReplyDeletecase "NotIn":
predicates.add(criterailBuilder.in(expression).value(searchFilter.getValue()).not());
break;