So I am trying to append a data to my database and have the database create the ID. this is the error that we are getting: {message: 'duplicate key value violates unique constraint "workoutDetail_pkey"', code: '23505', details: 'Key (id)=(3) already exists.', hint: null} in workoutDetail table i checked 'Is Identity' for column id

First, please post these type questions in one of the help threads next time and don't keep adding posts, instead start a thread. 'Is Identity' will generate a new incrementing number on insert, unless you actual include a value for that column in the insert. Putting a value will insert that in the column. If you have ever done that, it could mess up the incrementing process, possibly at a later point.