Properties — ASL

Properties

Properties map to columns.

type User {
  required email: str;           # NOT NULL column
  name: str;                     # nullable column
  required property age: int32;  # "property" keyword is optional
}

Required

required maps to NOT NULL.

Defaults

active: bool { default := true };
name: str    { default := 'anonymous'; };
score: int32 { default := 0; };

# Functions
id:         uuid     { default := gen_uuid(); };
created_at: datetime { default := datetime_current(); };

A default runs once, on INSERT. To re-assign a field on later updates, see Rewrites.

Declaring a default also matters when you add a required field to a table that already has rows: with one, Axel backfills existing rows itself; without one, the migration leaves a seam you must fill in. See axel diff.

Multi (array) properties

multi on a property declares a PostgreSQL array column — one column, not a junction table. (multi on a link means something else entirely; see Links.)

type User {
  multi roles: UserType;    # TEXT[] with a containment check
  multi images: str;        # TEXT[]
  multi scores: float64;    # DOUBLE PRECISION[]
}

"roles"  TEXT[] CONSTRAINT "chk_user_roles_enum" CHECK ("roles" <@ ARRAY['Admin', 'Runner', 'Vendor']::TEXT[]),
"images" TEXT[],
"scores" DOUBLE PRECISION[]

An enum array is stored as TEXT[] guarded by a containment check rather than as a Postgres enum array.

Two consequences worth knowing:

• Membership compiles to = ANY(...), not IN — Postgres IN takes a parenthesised list and rejects an array operand.

  select User { id } filter UserType.Admin in .roles;   # → 'Admin' = ANY(u.roles)

• Generated clients type it as an array, with the nullability outside the array: roles?: UserType[] | null in TypeScript, []UserType in Go — in the models and in query result rows alike.