Penguin Random House Developer Blog

Back on August 1, 2018, we announced a change to how work attributes are derived. One of these changes was to the on-sale date that is associated with a work using the date of the most representative ("frontlistiest") ISBN rather than the earliest. However we preserved the earliest on-sale date in a column we call FIRST_ONSALEDATE and so going forward, works have two dates associated with them

• onsaledate : the on-sale date of the representative ISBN (often the most recent)
• first_onsaledate : the on-sale date of the earliest ISBN that is part of this work (always the oldest)

To maintain backward compatability, we migrated the filter parameters workOnSaleFrom and workOnSaleTo to test against the "first_onsaledate" field however this does not suit the names of those parameters. Therefore in the next release of the API, this will be changing to instead operate against the "onsaledate" (most recent) field. To preserve the existing functionality, you will need to access the new parameters workFirstOnSaleFrom and workFirstOnSaleTo.