An Ecto.Type storing an Elixir Date.Range.t/0 in a PostgreSQL daterange column.

A range such as Date.range(~D[2024-01-01], ~D[2024-12-31]) stores and loads as itself, so a span of dates is a first-class value in a schema. daterange is a built-in PostgreSQL type, so no migration beyond the column is needed, and the column can be queried with the range operators (@>, &&) — including an exclusion constraint that forbids overlapping spans — and indexed with a GiST index.

Schema

# in a migration
add :period, :daterange

# in a schema
field :period, Localize.Ecto.Type.DateRange

Semantics

Date.Range is inclusive of both ends, so Date.range(~D[2024-01-01], ~D[2024-12-31]) covers the whole year; it is stored as the PostgreSQL range [2024-01-01, 2024-12-31] and read back inclusive regardless of the bound form PostgreSQL canonicalizes to (it stores daterange as [lower, upper)).

Only ascending day-step ranges are storable — a range carrying a step other than one day, or a descending one, has no daterange equivalent and is rejected on cast and dump.