Shows how to enable logging for Grails database connections.

grails-logging.md

Full stack traces

To enable full stack traces just add the command line argument -Dgrails.full.stacktrace=true when calling grails, e. g.:

grails -Dgrails.full.stacktrace=true run-app

SQL logging

First you can enable SQL logging by adding the property logSql = true to the data source (in DataSource.groovy), e. g.:

environments {
    development {
        dataSource {
            url = 'jdbc:mysql://localhost/dbname?autoreconnect=true'
            username = 'user'
            password = 'secretpwd'
            logSql = true
        }
    }
}

This method has the disadvantage that the SQL commands are visible, though, the bound values are not.

Advanced SQL logging

To produce more output, format the SQL commands, and see the bound parameter values, first turn off the logSql property for the database because otherwise it'll output SQL commands twice.

Then add the following properties in DataSource.groovy:

hibernate {
    format_sql = true
    use_sql_comments = true
}

This will produce far more readable SQL commands than simply logSql would do. Then, add the following log4j settings to Config.groovy:

log4j = {
    debug 'org.hibernate.SQL'
    trace 'org.hibernate.type'
}

The first setting logs the SQL commands, the second one logs the bound parameters and the bindings of the result set.