Three ways solving Spring Boot Cannot determine embedded database driver class for database type NONE

If you don’t have a DataSource configured for your spring boot application, when you run spring boot application, it tries to configure the DataSource and throws this error message when there is no configuration provided.

We have three ways to slove this:

1) If you don't need any data source, just exclude it as below:

@SpringBootApplication
@EnableAutoConfiguration(exclude={DataSourceAutoConfiguration.class})
public class SpringBootDemoApplication { }

2) If you need ds just for test purpose, say using an embedded DB like HSqldb, just add the dependency in your pom or yml file:

<dependency>

 <groupId>org.hsqldb</groupId>

 <artifactId>hsqldb</artifactId>

 <scope>runtime</scope>

</dependency>

3) Or you want to have your own external DB configuration, you need to provided DS information in spring boot configuration file, generally add below into application.properties is fine:

spring.datasource.url=xxx

spring.datasource.* is the default prefix for spring boot data source configuration, if you use other prefix, you may need add your own ds configuration file.

access-control-allow-origin

When do development, especially front end and back end are separated in different projects, it is easy to get  access-control-allow-origin error when call webservices.

For this, we have some solutions:

1) For front end, we can add some proxy logic to redirect front end HTTP request through proxy, for instance, our front end application runs on http://localhost:3000, and back end application on http://localhost:8000, if front end make a service call to back end, say /api/v1/students, the call will proxyed to http://localhost:8000/api/v1/students, not http://localhost:3000/api/v1/students, thus avoiding access-control-allow-origin error from the browser. for instance, if you use gulp serve, in server.js file, you can use 'http-proxy-middleware':

var proxyMiddleware = require('http-proxy-middleware');
server.middleware = proxyMiddleware('/api', {target: 'http://localhost:8888', changeOrigin: true});

For 'http-proxy-middleware' can get more info in: https://github.com/chimurai/http-proxy-middleware

2) Otherwise, we can add some logic on back end, e.g. if we use spring framework,  we can use @CrossOrigin annotation on method, class or global level. For global enabled we can add this annotation in one of the configuration classes is OK：

@Configuration @CrossOrigin public class WebConfig { }

3) Or we can just do something without code, say if we use Chrome, we can add the plugin

This will also avoid this error.