Docs: outsideGrails.adoc about gorm-hibernate5 HOT 4 CLOSED

As mentioned in http://gorm.grails.org/6.0.x/hibernate/manual/index.html#outsideGrails you need to declare the necessary dependencies. The dependencies that are not in the example you have that are mentioned as being necessary in the docs are the connection pool to use:

runtime "org.apache.tomcat:tomcat-jdbc:8.5.0"
runtime "org.apache.tomcat.embed:tomcat-embed-logging-log4j:8.5.0"

The connection pool can be commons-dbcp, tomcat pool or hikari. If you don't specify a connection pool then a org.springframework.jdbc.datasource.DriverManagerDataSource is used, which creates a new connection to the database each time you request a connect.

The problem with this when you use an in-memory database is that h2 is creating a new in-memory database each time a connection is requested. So the tables that were created previously are lost. If you were using a normal database (mysql, postgres or h2 file based database) your example would work fine.

It is the combination of DriverManagerDataSource, which creates and initialises a brand new in-memory database each time a connection is requested (because it is not a pool), and h2 in-memory that causes the issue you are seeing.

That is why we include a connection pool in the list of necessary dependencies, since people are likely to stumble into this (as you have) and also any real production application would use a pool.

from gorm-hibernate5.

RIght. I'm going to create a PR which describes this a bit better in the docs.

from gorm-hibernate5.

On that note of docs isn't the use of implements GormEntity<Person> redundant? I thought @Entity effectively does that.

from gorm-hibernate5.

It is, but some IDEs use the fact that the class is in grails-app/domain to enable code completion. So by being explicit about implementing the trait you are more likely to obtain completions etc.

from gorm-hibernate5.