Getting a Connection to a Postgresql database from a Datasource created with Spring's DataSourceBuilder

Question

I am new to Spring and Spring Boot. I am trying to connect to a Postgresql database in my Spring Boot app. I've tried to take inspiration from

http://spring.io/guides/gs/accessing-data-mysql/

and

https://docs.spring.io/spring-boot/docs/current/reference/html/howto-data-access.html

Basically I have an application.properties file that contains:

app.datasource.url=jdbc:postgresql://localhost:5432/db_example
app.datasource.username=myusername
app.datasource.password=mypassword
app.datasource.driver-class-name=org.postgresql.Driver

Using the psql tool I can normally connect to the db_example database on localhost with the 5432 port and those username and password.

Then I have a MyConfig.java which contains:

package hello;

import javax.sql.DataSource;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;

@Configuration
public class MyConfig {

    @Bean
    @Primary
    @ConfigurationProperties(prefix = "app.datasource")
    public DataSource dataSource() {
        DataSourceBuilder dsb = DataSourceBuilder.create();
        if (dsb == null) {
            return null;
        }
        return dsb.build();
    }

}

Then in MainController.java one of the methods that has a @GetMapping annotation, I call the dataSource() method. On the returned object I call getConnection() but that throws an SQLException with message The url cannot be null.

Also in the console the Spring Boot app writes several things:

Not loading a JDBC driver as driverClassName property is null.

and

Unable to create initial connections of pool

What am I missing? I guess some annotation in MyConfig.java?

EDIT: You might also want to see my pom.xml used to package the thing with mvn:

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.springframework</groupId>
    <artifactId>gs-mysql-data</artifactId>
    <version>0.1.0</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.8.RELEASE</version>
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!-- JPA Data (We are going to use Repositories, Entities, Hibernate, etc...) -->

        <!--<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>-->

        <!-- Use MySQL Connector-J -->

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

         <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

I guess driver-class-name should be driverClassName in your application.properties — user330315
– user330315, Commented Nov 20, 2017 at 22:37

Kenny Tai Huynh · Accepted Answer · 2017-11-20 23:21:59Z

3

It seems DataSourceBuilder is not set the properties. Can you try to use the default config in Spring like:

spring.datasource.url=jdbc:postgresql://localhost:5432/db_example
spring.datasource.username=myusername
spring.datasource.password=mypassword
spring.datasource.driver-class-name=org.postgresql.Driver

More detail in here: https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-sql.html

Then in your code, you have to get these properties and set them:

@Value("${spring.datasource.url}")
private String url;
@Value("${spring.datasource.username}")
private String username;
@Value("${spring.datasource.password}")
private String password;
@Value("${spring.datasource.driver-class-name}")
private String driver;

DataSourceBuilder dataSourceBuilder = DataSourceBuilder.create();
dataSourceBuilder.driverClassName(driver);
dataSourceBuilder.username(username);
dataSourceBuilder.password(password);
dataSourceBuilder.url(url)

Hope this help.

answered Nov 20, 2017 at 23:21

Kenny Tai Huynh

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1 Comment

IJK_Principle Over a year ago

Thanks Kenny, I'll try this and let know if it helped.

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