改造为 Maven 多模块项目后报错：If you want an embedded database (H2, HSQL or Derby), please put it on the classpath.

情景

一个 Maven 单模块项目改造为多模块项目后，发现报错：

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APPLICATION FAILED TO START
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Description:

Failed to configure a DataSource: 'url' attribute is not specified and no embedded datasource could be configured.

Reason: Failed to determine a suitable driver class


Action:

Consider the following:
If you want an embedded database (H2, HSQL or Derby), please put it on the classpath.
If you have database settings to be loaded from a particular profile you may need to activate it (no profiles are currently active).


Process finished with exit code 1

一种可行的解决方案

如果是 Maven 多模块项目，查看 IDEA 右上角 Edit Configurations -> Use classpath of module，此栏应为 包含程序入口的 xxxApplication.java 和 application.yml 的 module：

如上图，博主的程序入口 xxxApplication.java 和 application.yml 放置于 server 这个 module，brother-takeaway-order 是之前单体模块的名称。把此处的 module 切换为 server，即可解决报错。