Tuesday 24 March 2020

Spring jpa: How to query on @EmbeddedId using Specification

'root.get({propertyName}).get({subPropertyName})' is used to query on embeddedId using specification.

For example, Project entity has ProjectId as embeddedId.
@Embeddable
public class ProjectId implements Serializable{

 private static final long serialVersionUID = 1L;

 @Column(name = "PROJECT_NAME")
 private String projectName;

 @Column(name = "ORGANIZATION")
 private String organization;

 ......
 ......

}


@Entity
@Table(name = "projects")
public class Project {

 @EmbeddedId
 private ProjectId projectId;

 @Column(name = "STARTED_TIME")
 private Timestamp startedTime;

 @Column(name = "ACTIVE")
 private String active;

 @Column(name = "DESCRIPTION")
 private String description;

 ......
 ......
}

To get the path for embedded fields projectName, organization we should use below logic.
Path expression = null;
if ("projectName".equals(property)) {
 expression = root.get("projectId").get("projectName");
} else if ("organization".equals(property)) {
 expression = root.get("projectId").get("organization");
} else {
 expression = root.get(property);
}

Similarly to sort on embedded id fields, we should access the nested fields using '.' notation like below.
Sort.Order.asc("projectId.projectName")
Sort.Order.asc("projectId.organization")
Sort.Order.desc("projectId.projectName")
Sort.Order.desc("projectId.organization")

Find the below working application.

App.java
package com.sample.app;

import java.sql.Timestamp;
import java.util.Arrays;

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.entity.Project;
import com.sample.app.repository.ProjectRepository;

@SpringBootApplication
public class App {

 public static void main(String args[]) {
  SpringApplication.run(App.class, args);
 }

 @Bean
 public CommandLineRunner demo(ProjectRepository projectRepository) {
  return (args) -> {
   Timestamp timeStamp = new Timestamp(System.currentTimeMillis());

   Project pjt1 = new Project("Chat Server", "IT", timeStamp, "y", "To chat with people");
   Project pjt2 = new Project("Cabin Control Engine", "IT Services", timeStamp, "y",
     "To main cabin temperature and pressure");
   Project pjt3 = new Project("Advanced Search Engine", "Research Labs", timeStamp, "y",
     "Search based on user profile");
   Project pjt4 = new Project("CRM", "IT Services", timeStamp, "y", "Customer Relationship management");
   
   projectRepository.saveAll(Arrays.asList(pjt1, pjt2, pjt3, pjt4));

  };
 }
}

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();
 }
}

ProjectController.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.entity.Project;
import com.sample.app.model.SearchQuery;
import com.sample.app.service.ProjectService;

import io.swagger.annotations.ApiOperation;

@RestController
public class ProjectController {

 @Autowired
 private ProjectService projectService;

 @ApiOperation(value = "Projects Filter", notes = "Get projects by search criteria")
 @PostMapping(value = "/projects", produces = MediaType.APPLICATION_JSON_VALUE)
 public ResponseEntity<List<Project>> getEmployees(@RequestBody SearchQuery searchQuery) {
  List<Project> emps = projectService.findAll(searchQuery);

  return new ResponseEntity<>(emps, HttpStatus.OK);
 }
}

Project.java
package com.sample.app.entity;

import java.sql.Timestamp;

import javax.persistence.Column;
import javax.persistence.EmbeddedId;
import javax.persistence.Entity;
import javax.persistence.Table;

@Entity
@Table(name = "projects")
public class Project {

 @EmbeddedId
 private ProjectId projectId;

 @Column(name = "STARTED_TIME")
 private Timestamp startedTime;

 @Column(name = "ACTIVE")
 private String active;

 @Column(name = "DESCRIPTION")
 private String description;

 public Project() {

 }

 public Project(String projectName, String organization, Timestamp startedTime, String active, String description) {
  ProjectId projectId = new ProjectId(projectName, organization);
  this.projectId = projectId;
  this.startedTime = startedTime;
  this.active = active;
  this.description = description;
 }

 public ProjectId getProjectId() {
  return projectId;
 }

 public void setProjectId(ProjectId projectId) {
  this.projectId = projectId;
 }

 public Timestamp getStartedTime() {
  return startedTime;
 }

 public void setStartedTime(Timestamp startedTime) {
  this.startedTime = startedTime;
 }

 public String getActive() {
  return active;
 }

 public void setActive(String active) {
  this.active = active;
 }

 public String getDescription() {
  return description;
 }

 public void setDescription(String description) {
  this.description = description;
 }

}

ProjectId.java
package com.sample.app.entity;

import java.io.Serializable;

import javax.persistence.Column;
import javax.persistence.Embeddable;

@Embeddable
public class ProjectId implements Serializable{

 private static final long serialVersionUID = 1L;

 @Column(name = "PROJECT_NAME")
 private String projectName;

 @Column(name = "ORGANIZATION")
 private String organization;

 public ProjectId() {

 }

 public ProjectId(String projectName, String organization) {
  this.projectName = projectName;
  this.organization = organization;
 }

 public String getProjectName() {
  return projectName;
 }

 public void setProjectName(String projectName) {
  this.projectName = projectName;
 }

 public String getOrganization() {
  return organization;
 }

 public void setOrganization(String organization) {
  this.organization = organization;
 }

}

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;

 private int pageNumber;
 private int pageSize;

 private SortOrder sortOrder;

 public List<SearchFilter> getSearchFitler() {
  return searchFitler;
 }

 public void setSearchFitler(List<SearchFilter> searchFitler) {
  this.searchFitler = searchFitler;
 }

 public int getPageNumber() {
  return pageNumber;
 }

 public void setPageNumber(int pageNumber) {
  this.pageNumber = pageNumber;
 }

 public int getPageSize() {
  return pageSize;
 }

 public void setPageSize(int pageSize) {
  this.pageSize = pageSize;
 }

 public SortOrder getSortOrder() {
  return sortOrder;
 }

 public void setSortOrder(SortOrder sortOrder) {
  this.sortOrder = sortOrder;
 }

}

SortOrder.java
package com.sample.app.model;

import java.util.List;

public class SortOrder {

 private List<String> ascendingOrder;

 private List<String> descendingOrder;

 public List<String> getAscendingOrder() {
  return ascendingOrder;
 }

 public void setAscendingOrder(List<String> ascendingOrder) {
  this.ascendingOrder = ascendingOrder;
 }

 public List<String> getDescendingOrder() {
  return descendingOrder;
 }

 public void setDescendingOrder(List<String> descendingOrder) {
  this.descendingOrder = descendingOrder;
 }

}

ProjectRepository.java
package com.sample.app.repository;

import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.springframework.data.repository.PagingAndSortingRepository;

import com.sample.app.entity.Project;
import com.sample.app.entity.ProjectId;

public interface ProjectRepository extends JpaSpecificationExecutor<Project>, PagingAndSortingRepository<Project, ProjectId>{

}

ProjectService.java
package com.sample.app.service;

import java.util.List;

import com.sample.app.entity.Project;
import com.sample.app.model.SearchQuery;

public interface ProjectService {

  public List<Project> findAll(SearchQuery searchQuery);
}

ProjectServiceImpl.java
package com.sample.app.service.impl;

import java.util.ArrayList;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Sort;
import org.springframework.data.jpa.domain.Specification;
import org.springframework.stereotype.Service;

import com.sample.app.entity.Project;
import com.sample.app.model.SearchQuery;
import com.sample.app.model.SortOrder;
import com.sample.app.repository.ProjectRepository;
import com.sample.app.service.ProjectService;
import com.sample.app.specification.SpecificationUtil;

@Service
public class ProjectServiceImpl implements ProjectService {

 @Autowired
 private ProjectRepository projectRepository;

 @Override
 public List<Project> findAll(SearchQuery searchQuery) {
  Specification<Project> spec = SpecificationUtil.bySearchQuery(searchQuery, Project.class);
  PageRequest pageRequest = getPageRequest(searchQuery);

  Page<Project> page = projectRepository.findAll(spec, pageRequest);

  return page.getContent();
 }

 private PageRequest getPageRequest(SearchQuery searchQuery) {

  int pageNumber = searchQuery.getPageNumber();
  int pageSize = searchQuery.getPageSize();

  List<Sort.Order> orders = new ArrayList<>();

  SortOrder sortOrder = searchQuery.getSortOrder();

  if (sortOrder == null) {
   return PageRequest.of(pageNumber, pageSize, null);
  }

  List<String> ascProps = searchQuery.getSortOrder().getAscendingOrder();

  if (ascProps != null && !ascProps.isEmpty()) {
   for (String property : ascProps) {

    if ("projectName".equals(property)) {
     orders.add(Sort.Order.asc("projectId.projectName"));
    } else if ("organization".equals(property)) {
     orders.add(Sort.Order.asc("projectId.organization"));
    } else {
     orders.add(Sort.Order.asc(property));
    }
   }

  }

  List<String> descProps = searchQuery.getSortOrder().getDescendingOrder();

  if (descProps != null && !descProps.isEmpty()) {
   for (String property : descProps) {
    if ("projectName".equals(property)) {
     orders.add(Sort.Order.desc("projectId.projectName"));
    } else if ("organization".equals(property)) {
     orders.add(Sort.Order.desc("projectId.organization"));
    } else {
     orders.add(Sort.Order.desc(property));
    }
   }

  }

  Sort sort = Sort.by(orders);

  return PageRequest.of(pageNumber, pageSize, sort);

 }

}

SpecificationUtil.java
package com.sample.app.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 = null;

    if ("projectName".equals(property)) {
     expression = root.get("projectId").get("projectName");
    } else if ("organization".equals(property)) {
     expression = root.get("projectId").get("organization");
    } else {
     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]));

  };
 }
}

Create ‘application.properties’ file under src/main/resources folder.

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>com.sample.app</groupId>
 <artifactId>embeddedIdQueryUsingSpecification</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 browse to get swagger UI.

Hit /projects API with below payload.
{
  "pageNumber": 0,
  "pageSize": 10,
  "searchFitler": [
    {
      "operator": "LIKE",
      "property": "projectName",
      "value": "Engine"
    }
  ],
  "sortOrder": {
    "ascendingOrder": [
      "projectName"
    ],

    "descendingOrder" : [
      "organization"
    ]
  }
}

You will receive below response.
[
  {
    "projectId": {
      "projectName": "Advanced Search Engine",
      "organization": "Research Labs"
    },
    "startedTime": "2020-01-09T08:50:27.457+0000",
    "active": "y",
    "description": "Search based on user profile"
  },
  {
    "projectId": {
      "projectName": "Cabin Control Engine",
      "organization": "IT Services"
    },
    "startedTime": "2020-01-09T08:50:27.457+0000",
    "active": "y",
    "description": "To main cabin temperature and pressure"
  }
]


You can download complete working application from this link.


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