Issue
I doing the maintenance of this code please can someone explain what is that notation Post_ in the code below? I know Post is a model that I created, but Post_ with underscore is not in files. I searched but didnt find any information about this. Its a pre generated Spring Boot file? And if so how to create it?
import java.util.ArrayList;
import java.util.Collection;
import java.util.Optional;
import javax.persistence.criteria.Expression;
import javax.persistence.criteria.Predicate;
import org.springframework.data.jpa.domain.Specification;
import com.example.demo.dto.filter.PostFilter;
import com.example.demo.model.Post;
import com.example.demo.model.Post_;
public class PostSpecs extends BaseSpecs {
public static Specification<Post> specByFilter(Optional<PostFilter> filter) {
return filter.isEmpty() ? null : (root, query, builder) -> {
Collection<Predicate> predicates = new ArrayList<>();
predicates.add(equal(builder, root.get(Post_.ID), filter.map(PostFilter::getId)));
predicates.add(contains(builder, root.get(Post_.TITLE), filter.map(PostFilter::getTitle)));
predicates.add(contains(builder, root.get(Post_.BODY), filter.map(PostFilter::getBody)));
Expression<String> allCols = concatAll(builder, root.get(Post_.ID), root.get(Post_.TITLE),
root.get(Post_.BODY));
predicates.add(contains(builder, allCols, filter.map(PostFilter::getAny)));
return toAndArray(builder, predicates);
};
}
}
Post Class
package com.example.demo.model;
import java.time.LocalDateTime;
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.ManyToOne;
import javax.validation.constraints.NotBlank;
import org.springframework.data.annotation.CreatedBy;
import org.springframework.data.annotation.CreatedDate;
import org.springframework.data.annotation.LastModifiedDate;
import org.springframework.data.jpa.domain.support.AuditingEntityListener;
@Entity
@EntityListeners(AuditingEntityListener.class)
public class Post {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@CreatedDate
private LocalDateTime createdAt;
@LastModifiedDate
private LocalDateTime updatedAt;
@CreatedBy
private Long createdBy;
@NotBlank
@Column(length = 100)
private String title;
@NotBlank
@Column(length = 500)
private String body;
@ManyToOne
private User user;
public Post() {
}
public Post(Long id, String title, String body) {
this.id = id;
this.title = title;
this.body = body;
}
public Post(String title, String body) {
this.title = title;
this.body = body;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public LocalDateTime getCreatedAt() {
return createdAt;
}
public void setCreatedAt(LocalDateTime createdAt) {
this.createdAt = createdAt;
}
public LocalDateTime getUpdatedAt() {
return updatedAt;
}
public void setUpdatedAt(LocalDateTime updatedAt) {
this.updatedAt = updatedAt;
}
public Long getCreatedBy() {
return createdBy;
}
public void setCreatedBy(Long createdBy) {
this.createdBy = createdBy;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getBody() {
return body;
}
public void setBody(String body) {
this.body = body;
}
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
}
Pom.XML
<?xml version="1.0" encoding="UTF-8"?>
<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.3.3.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.example</groupId>
<artifactId>demo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>demo</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>11</java.version>
<springdoc.version>1.4.3</springdoc.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<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>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<scope>runtime</scope>
<optional>true</optional>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-configuration-processor</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springdoc</groupId>
<artifactId>springdoc-openapi-ui</artifactId>
<version>${springdoc.version}</version>
</dependency>
<dependency>
<groupId>org.springdoc</groupId>
<artifactId>springdoc-openapi-data-rest</artifactId>
<version>${springdoc.version}</version>
</dependency>
<!-- Lorem Ipsum to generate test data -->
<dependency>
<groupId>com.thedeanda</groupId>
<artifactId>lorem</artifactId>
<version>2.1</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.bsc.maven</groupId>
<artifactId>maven-processor-plugin</artifactId>
<version>3.3.3</version>
<executions>
<execution>
<id>process</id>
<goals>
<goal>process</goal>
</goals>
<phase>generate-sources</phase>
<configuration>
<processors>
<processor>org.hibernate.jpamodelgen.JPAMetaModelEntityProcessor</processor>
</processors>
</configuration>
</execution>
</executions>
<dependencies>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-jpamodelgen</artifactId>
<version>${hibernate.version}</version>
</dependency>
</dependencies>
</plugin>
</plugins>
</build>
</project>
Solution
That is the outcome of using Hibernate JPA 2 Metamodel Generator (see hibernate-jpamodelgen in your pom.xml).
You can find more information about it at https://docs.jboss.org/hibernate/stable/jpamodelgen/reference/en-US/html_single/.
Hibernate Static Metamodel Generator is an annotation processor based on the [Pluggable Annotation Processing API] with the task of creating JPA 2 static metamodel classes.
Answered By - João Dias
Answer Checked By - Clifford M. (JavaFixing Volunteer)
