October 15, 2008

jdbcpostgres-adapter and the numeric datatype

Vanilla Ruby with the postgres-pr adapter stores the 'numeric' datatype to BigDecimal. Unlike expected, the column has to explicitly define 'precision' and 'scale' when used in JRuby with the JDBC adapter, otherwise the scale is assumed to be 0 and all decimals are dropped. I have a column 'weight' in a table, in the original migration:

t.column :weight, :decimal, :null => false

This was corrected with the migration:
def self.up
  change_column :weights, :weight, :decimal, :null => false, :precision => 4, :scale => 1

def self.down
  change_column :weights, :weight, :decimal, :null => false