Edit an expense

Send only the fields to change: date, memo, property and GL code, and the amount of a general expense (a mileage expense's amount comes from its miles). The expense's own user or a role with the Reimbursements edit permission may edit it, with the app form's per-state locks: the amount locks once submitted, date and memo once reviewed, the submitter can't edit their own submitted expense, and nothing changes once it's approved or reimbursed. Referenced ids must belong to the account.