spring-boot-postgresql-maven-example-feature-image

Spring Boot, PostgreSQL example with Maven & Spring JPA

In this tutorial, we’re gonna build a Spring Boot Rest CRUD API example with Maven that use Spring Data JPA to interact with PostgreSQL database. You’ll know:

  • How to configure Spring Data, JPA, Hibernate to work with PostgreSQL Database
  • How to define Data Models and Repository interfaces
  • Way to create Spring Rest Controller to process HTTP requests
  • Way to use Spring Data JPA to interact with PostgreSQL Database

More Practice:
Secure Spring Boot App with Spring Security & JWT Authentication
Spring Boot Rest XML example – Web service with XML Response
Spring Boot Multipart File upload example
Spring Boot Pagination and Sorting example

Fullstack:
Spring Boot + Vue.js example: Build a CRUD App
Spring Boot + Angular + PostgreSQL example: Build a CRUD App
Spring Boot + React + PostgreSQL example: Build a CRUD App

Exception Handling:
Spring Boot @ControllerAdvice & @ExceptionHandler example
@RestControllerAdvice example in Spring Boot

Testing: Spring Boot Unit Test for JPA Repositiory with @DataJpaTest

Overview of Spring Boot, PostgreSQL example with Maven

We will build a Spring Boot + PostgreSQL + Rest CRUD API for a Tutorial application in that:

  • Each Tutotial has id, title, description, published status.
  • Apis help to create, retrieve, update, delete Tutorials.
  • Apis also support custom finder methods such as find by published status or by title.

These are APIs that we need to provide:

MethodsUrlsActions
POST/api/tutorialscreate new Tutorial
GET/api/tutorialsretrieve all Tutorials
GET/api/tutorials/:idretrieve a Tutorial by :id
PUT/api/tutorials/:idupdate a Tutorial by :id
DELETE/api/tutorials/:iddelete a Tutorial by :id
DELETE/api/tutorialsdelete all Tutorials
GET/api/tutorials/publishedfind all published Tutorials
GET/api/tutorials?title=[keyword]find all Tutorials which title contains keyword

– We make CRUD operations & finder methods with Spring Data JPA’s JpaRepository.
– The database will be PostgreSQL by configuring project dependency & datasource.

Technology

  • Java 8
  • Spring Boot 2 (with Spring Web MVC, Spring Data JPA)
  • PostgreSQL
  • Maven 3.6.1

Maven Project Structure

spring-boot-postgresql-maven-example-project-structure

Let me explain it briefly.

Tutorial data model class corresponds to entity and table tutorials.
TutorialRepository is an interface that extends JpaRepository for CRUD methods and custom finder methods. It will be autowired in TutorialController.
TutorialController is a RestController which has request mapping methods for RESTful requests such as: getAllTutorials, createTutorial, updateTutorial, deleteTutorial, findByPublished
– Configuration for Spring Datasource, JPA & Hibernate in application.properties.
pom.xml contains dependencies for Spring Boot and PostgreSQL.

Create & Setup Spring Boot project

Use Spring web tool or your development tool (Spring Tool Suite, Eclipse, Intellij) to create a Spring Boot Maven project.

Then open pom.xml and add these 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-web</artifactId>
</dependency>

We also need to add one more dependency for PostgreSQL:

<dependency>
	<groupId>org.postgresql</groupId>
	<artifactId>postgresql</artifactId>
	<scope>runtime</scope>
</dependency>

Configure Spring Datasource, JPA, Hibernate

Under src/main/resources folder, open application.properties and write these lines.

spring.datasource.url= jdbc:postgresql://localhost:5432/testdb
spring.datasource.username= postgres
spring.datasource.password= 123

spring.jpa.properties.hibernate.jdbc.lob.non_contextual_creation= true
spring.jpa.properties.hibernate.dialect= org.hibernate.dialect.PostgreSQLDialect

# Hibernate ddl auto (create, create-drop, validate, update)
spring.jpa.hibernate.ddl-auto= update
  • spring.datasource.username & spring.datasource.password properties are the same as your database installation.
  • Spring Boot uses Hibernate for JPA implementation, we configure PostgreSQLDialect for PostgreSQL
  • spring.jpa.hibernate.ddl-auto is used for database initialization. We set the value to update value so that a table will be created in the database automatically corresponding to defined data model. Any change to the model will also trigger an update to the table. For production, this property should be validate.

Define Data Model

Our Data model is Tutorial with four fields: id, title, description, published.
In model package, we define Tutorial class.

model/Tutorial.java

package com.bezkoder.spring.jpa.postgresql.model;

import javax.persistence.*;

@Entity
@Table(name = "tutorials")
public class Tutorial {

	@Id
	@GeneratedValue(strategy = GenerationType.AUTO)
	private long id;

	@Column(name = "title")
	private String title;

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

	@Column(name = "published")
	private boolean published;

	public Tutorial() {

	}

	public Tutorial(String title, String description, boolean published) {
		this.title = title;
		this.description = description;
		this.published = published;
	}

	public long getId() {
		return id;
	}

	public String getTitle() {
		return title;
	}

	public void setTitle(String title) {
		this.title = title;
	}

	public String getDescription() {
		return description;
	}

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

	public boolean isPublished() {
		return published;
	}

	public void setPublished(boolean isPublished) {
		this.published = isPublished;
	}

	@Override
	public String toString() {
		return "Tutorial [id=" + id + ", title=" + title + ", desc=" + description + ", published=" + published + "]";
	}
}

@Entity annotation indicates that the class is a persistent Java class.
@Table annotation provides the table that maps this entity.
@Id annotation is for the primary key.
@GeneratedValue annotation is used to define generation strategy for the primary key. GenerationType.AUTO means Auto Increment field.
@Column annotation is used to define the column in database that maps annotated field.

Create Repository Interface

Let’s create a repository to interact with Tutorials from the database.
In repository package, create TutorialRepository interface that extends JpaRepository.

repository/TutorialRepository.java

package com.bezkoder.spring.jpa.postgresql.repository;

import java.util.List;

import org.springframework.data.jpa.repository.JpaRepository;

import com.bezkoder.spring.jpa.postgresql.model.Tutorial;

public interface TutorialRepository extends JpaRepository<Tutorial, Long> {
  List<Tutorial> findByPublished(boolean published);

  List<Tutorial> findByTitleContaining(String title);
}

Now we can use JpaRepository’s methods: save(), findOne(), findById(), findAll(), count(), delete(), deleteById()… without implementing these methods.

We also define custom finder methods:
findByPublished(): returns all Tutorials with published having value as input published.
findByTitleContaining(): returns all Tutorials which title contains input title.

The implementation is plugged in by Spring Data JPA automatically.

You can modify this Repository:
– to work with Pagination, the instruction can be found at:
Spring Boot Pagination & Filter example | Spring JPA, Pageable
– or to sort/order by multiple fields with the tutorial:
Spring Data JPA Sort/Order by multiple Columns | Spring Boot

You also find way to write Unit Test for this JPA Repository at:
Spring Boot Unit Test for JPA Repositiory with @DataJpaTest

Create Spring Rest APIs Controller

Finally, we create a controller that provides APIs for creating, retrieving, updating, deleting and finding Tutorials.

controller/TutorialController.java

package com.bezkoder.spring.jpa.postgresql.controller;

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

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.CrossOrigin;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import com.bezkoder.spring.jpa.postgresql.model.Tutorial;
import com.bezkoder.spring.jpa.postgresql.repository.TutorialRepository;

@CrossOrigin(origins = "http://localhost:8081")
@RestController
@RequestMapping("/api")
public class TutorialController {

	@Autowired
	TutorialRepository tutorialRepository;

	@GetMapping("/tutorials")
	public ResponseEntity<List<Tutorial>> getAllTutorials(@RequestParam(required = false) String title) {
		try {
			List<Tutorial> tutorials = new ArrayList<Tutorial>();

			if (title == null)
				tutorialRepository.findAll().forEach(tutorials::add);
			else
				tutorialRepository.findByTitleContaining(title).forEach(tutorials::add);

			if (tutorials.isEmpty()) {
				return new ResponseEntity<>(HttpStatus.NO_CONTENT);
			}

			return new ResponseEntity<>(tutorials, HttpStatus.OK);
		} catch (Exception e) {
			return new ResponseEntity<>(null, HttpStatus.INTERNAL_SERVER_ERROR);
		}
	}

	@GetMapping("/tutorials/{id}")
	public ResponseEntity<Tutorial> getTutorialById(@PathVariable("id") long id) {
		Optional<Tutorial> tutorialData = tutorialRepository.findById(id);

		if (tutorialData.isPresent()) {
			return new ResponseEntity<>(tutorialData.get(), HttpStatus.OK);
		} else {
			return new ResponseEntity<>(HttpStatus.NOT_FOUND);
		}
	}

	@PostMapping("/tutorials")
	public ResponseEntity<Tutorial> createTutorial(@RequestBody Tutorial tutorial) {
		try {
			Tutorial _tutorial = tutorialRepository
					.save(new Tutorial(tutorial.getTitle(), tutorial.getDescription(), false));
			return new ResponseEntity<>(_tutorial, HttpStatus.CREATED);
		} catch (Exception e) {
			return new ResponseEntity<>(null, HttpStatus.INTERNAL_SERVER_ERROR);
		}
	}

	@PutMapping("/tutorials/{id}")
	public ResponseEntity<Tutorial> updateTutorial(@PathVariable("id") long id, @RequestBody Tutorial tutorial) {
		Optional<Tutorial> tutorialData = tutorialRepository.findById(id);

		if (tutorialData.isPresent()) {
			Tutorial _tutorial = tutorialData.get();
			_tutorial.setTitle(tutorial.getTitle());
			_tutorial.setDescription(tutorial.getDescription());
			_tutorial.setPublished(tutorial.isPublished());
			return new ResponseEntity<>(tutorialRepository.save(_tutorial), HttpStatus.OK);
		} else {
			return new ResponseEntity<>(HttpStatus.NOT_FOUND);
		}
	}

	@DeleteMapping("/tutorials/{id}")
	public ResponseEntity<HttpStatus> deleteTutorial(@PathVariable("id") long id) {
		try {
			tutorialRepository.deleteById(id);
			return new ResponseEntity<>(HttpStatus.NO_CONTENT);
		} catch (Exception e) {
			return new ResponseEntity<>(HttpStatus.INTERNAL_SERVER_ERROR);
		}
	}

	@DeleteMapping("/tutorials")
	public ResponseEntity<HttpStatus> deleteAllTutorials() {
		try {
			tutorialRepository.deleteAll();
			return new ResponseEntity<>(HttpStatus.NO_CONTENT);
		} catch (Exception e) {
			return new ResponseEntity<>(HttpStatus.INTERNAL_SERVER_ERROR);
		}

	}

	@GetMapping("/tutorials/published")
	public ResponseEntity<List<Tutorial>> findByPublished() {
		try {
			List<Tutorial> tutorials = tutorialRepository.findByPublished(true);

			if (tutorials.isEmpty()) {
				return new ResponseEntity<>(HttpStatus.NO_CONTENT);
			}
			return new ResponseEntity<>(tutorials, HttpStatus.OK);
		} catch (Exception e) {
			return new ResponseEntity<>(HttpStatus.INTERNAL_SERVER_ERROR);
		}
	}
}

@CrossOrigin is for configuring allowed origins.
@RestController annotation is used to define a controller and to indicate that the return value of the methods should be be bound to the web response body.
@RequestMapping("/api") declares that all Apis’ url in the controller will start with /api.
– We use @Autowired to inject TutorialRepository bean to local variable.

Run & Test

Run Spring Boot application with command: mvn spring-boot:run.

tutorials table will be automatically generated in Database.
If you check PostgreSQL for example, you can see things like this:

testdb=# \d tutorials
             Table "public.tutorials"
   Column    |          Type          | Modifiers
-------------+------------------------+-----------
 id          | bigint                 | not null
 description | character varying(255) |
 published   | boolean                |
 title       | character varying(255) |
Indexes:
    "tutorials_pkey" PRIMARY KEY, btree (id)

Create some Tutorials:

spring-boot-postgresql-maven-example-create-tutorial

testdb=# SELECT * FROM tutorials;
 id |    description    | published |            title
----+-------------------+-----------+------------------------------
  1 | Tut#1 Description | f         | Spring Boot Tut#1
  2 | Tut#2 Description | f         | PostgreSQL Tut#2
  3 | Tut#3 Description | f         | Spring Data JPA Tut#3
  4 | Tut#4 Description | f         | Maven Tut#4
  5 | Tut#5 Description | f         | Spring Boot PostgreSQL Tut#5
(5 rows)

Update some Tutorials:

spring-boot-postgresql-maven-example-update-tutorial

testdb=# SELECT * FROM tutorials;
 id |    description    | published |            title
----+-------------------+-----------+------------------------------
  3 | Tut#3 Description | f         | Spring Data JPA Tut#3
  5 | Tut#5 Description | f         | Spring Boot PostgreSQL Tut#5
  2 | Desc for Tut#2    | t         | PostgreSQL DB Tut#2
  4 | Desc for Tut#4    | t         | Maven Tut#4
  1 | Desc for Tut#1    | t         | Spring Boot Tut#1
(5 rows)

Get all Tutorials:

spring-boot-postgresql-maven-example-retrieve-all-tutorial

Get a Tutorial by Id:

spring-boot-postgresql-maven-example-get-one-tutorial

Find all published Tutorials:

spring-boot-postgresql-maven-example-find-active-tutorial

Find all Tutorials which title contains ‘ring’:

spring-boot-postgresql-maven-example-find-title-tutorial

Delete a Tutorial:

spring-boot-postgresql-maven-example-delete-one-tutorial

testdb=# SELECT * FROM tutorials;
 id |    description    | published |            title
----+-------------------+-----------+------------------------------
  3 | Tut#3 Description | f         | Spring Data JPA Tut#3
  5 | Tut#5 Description | f         | Spring Boot PostgreSQL Tut#5
  2 | Desc for Tut#2    | t         | PostgreSQL DB Tut#2
  1 | Desc for Tut#1    | t         | Spring Boot Tut#1
(4 rows)

Delete all Tutorials:

spring-boot-postgresql-maven-example-delete-all-tutorial

testdb=# SELECT * FROM tutorials;
 id | description | published | title
----+-------------+-----------+-------
(0 rows)

Conclusion

Today we’ve built a Spring Boot PostgreSQL example with Rest CRUD API using Maven & Spring Data JPA, Hibernate.

We also see that JpaRepository supports a great way to make CRUD operations and custom finder methods without need of boilerplate code.

If you want to add Pagination to this Spring project, you can find the instruction at:
Spring Boot Pagination & Filter example | Spring JPA, Pageable

To sort/order by multiple fields:
Spring Data JPA Sort/Order by multiple Columns | Spring Boot

Handle Exception for this Rest APIs is necessary:
Spring Boot @ControllerAdvice & @ExceptionHandler example
@RestControllerAdvice example in Spring Boot

Or way to write Unit Test for the JPA Repository:
Spring Boot Unit Test for JPA Repositiory with @DataJpaTest

Happy learning! See you again.

Further Reading

Fullstack examples:
Spring Boot + Vue.js example: Build a CRUD App
Spring Boot + Angular + PostgreSQL example: Build a CRUD App
Spring Boot + React + PostgreSQL example: Build a CRUD App

Source Code

You can find the complete source code for this tutorial on Github.

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