$fields public property (available since version 2.0.7)
Column definition strings used for creating migration code. The format of each definition is COLUMN_NAME:COLUMN_TYPE:COLUMN_DECORATOR. Delimiter is ,. For example, --fields="name:string(12):notNull:unique" produces a string column of size 12 which is not null and unique values. Note: primary key is added automatically and is named id by default. If you want to use another name you may specify it explicitly like --fields="id_key:primary