Support rolling filters for date time cols

[aszenz]

Feature Request

Ability to always look at last quarters data for saved report

Description of Problem:

I want to create a dashboard which always shows last quarters data by default but include all the data. I also want to support my users in customizing the range of data they want to look at easily.

Potential Solutions:

Support rolling filters on date time columns:

• Previous/Current/Next quarter/month/week/year

On every load it should fetch the current date time and filter the data accordingly.

[texodus]

For static data, Perspective has partial support for this feature via a mix of the datetime() and now() ExprTK functions but it's not super ergonomic and has some quirks:

{
   // ...
  "filter": [
    ["is_within_last_five_minutes", "==", true],
  ],
  "expressions": {
    "is_within_last_five_minutes": '"my_datetime_column" > datetime(now() - 1000 * 60 * 5)'
  },

}

Unfortunately, for now Perspective columns do not re-calculate if their inputs don't change, so this won't work with streaming data and the cutoff value is basically frozen once the View is created.