I have a department table that has a jsonb field that give the hours of operation that looks like:

{
            "Friday": {
                "closeTime": "1970-01-01T17:00:00.000Z",
                "isOpen": true,
                "isOpen24Hours": false,
                "openTime": "1970-01-01T08:00:00.000Z"
            },
            "Monday": {
                "isOpen": false
            },
            "Saturday": {
                "isOpen": false
            },
            "Sunday": {
                "isOpen": false
            },
            "Thursday": {
                "closeTime": "1970-01-01T17:00:00.000Z",
                "isOpen": true,
                "isOpen24Hours": false,
                "openTime": "1970-01-01T08:00:00.000Z"
            },
            "Tuesday": {
                "closeTime": "1970-01-01T17:00:00.000Z",
                "isOpen": true,
                "isOpen24Hours": false,
                "openTime": "1970-01-01T08:00:00.000Z"
            },
            "Wednesday": {
                "closeTime": "1970-01-01T17:00:00.000Z",
                "isOpen": true,
                "isOpen24Hours": false,
                "openTime": "1970-01-01T08:00:00.000Z"
            }
        }

I have another table that associates some activity on a day with a department and I want to know if on the day that the activity happened is the department was open. So how do I query this jsonb field with the day of week of the date from the other table?

I have tried something like:

select a.activity_date, a.department_id, 
d.hours_of_operation->to_char(a.activity_date, 'Day')->>'isOpen' as isOpen
from activity a
join department d on a.department_id = d.id

but that only returns an isOpen value when the activity_date is a Wednesday (which is the last key in the hours_of_operation jsonb)