How to use a path relative to project root to H2 db-file configuration with Play Framework 2.4?

问题

We're developing a Play 2.4 application (Java API).

For dev purposes, we'd like to use a persistent H2 database with DB file path relative to the project root directory.

In How to use a persistent H2 database in the Play Framework instead of in-memory there was solution for Play 2.0:

db.default.url="jdbc:h2:file:data/db"

However, with Play 2.4 this doesn't seem to work but I get error message with the following exception at the bottom:

Caused by: org.h2.jdbc.JdbcSQLException: A file path that is implicitly 
relative to the current working directory is not allowed in the database
URL "jdbc:h2:file:data/db". Use an absolute path, ~/name, ./name, or the 
baseDir setting instead. [90011-187]
    at org.h2.message.DbException.getJdbcSQLException(DbException.java:345)
    at org.h2.message.DbException.get(DbException.java:179)
    ...

I could get connection to work with an absolute path and with a path relative to the home directory, like the following:

db.default.url="jdbc:h2:file:/Users/foo/data/db"

db.default.url="jdbc:h2:~/data/db"

However, is there some way to refer to the project root folder?

回答1:

Ok, I did a little research and found this in the changelog (http://www.h2database.com/html/changelog.html):

Implicit relative paths are disabled (system property "h2.implicitRelativePath"), so that the database URL jdbc:h2:test now needs to be written as jdbc:h2:./test.

In H2 starting from version 1.4.177 Beta, implicit relative paths are not allowed anymore. Therefore, in your case the url should be written with a explicit relative path: db.default.url="jdbc:h2:./data/db".