Data Types

This document defines the type system for domain definitions.

Primitive Types

Type	Description	Example
`text`	Variable-length string	`Name: text`
`text(N)`	String with max length	`Code: text(10)`
`integer`	32-bit whole number	`Count: integer`
`long`	64-bit whole number	`SizeBytes: long`
`decimal`	Arbitrary-precision decimal	`Rate: decimal`
`decimal(P,S)`	Decimal with precision and scale	`Rate: decimal(10,4)`
`boolean`	True or false	`IsActive: boolean`
`date`	Date without time	`StartDate: date`
`time`	Time without date	`OpenTime: time`
`datetime`	Date and time	`CreatedAt: datetime`
`guid`	Globally unique identifier	`Token: guid`
`name`	Smart name with casing variants	`FirstName: name`
`binary`	Raw binary data	`Data: binary`
`id`	Generated unique identifier (key fields only)	`ChildId: id`
`email`	Email address	`ContactEmail: email`
`url`	Web address	`WebsiteUrl: url`

Standard Library Types

These types are defined in the lib/ standard library. Use them by name — the code generator resolves their canonical definition.

Value Types

Type	Description	Library file
`money`	ISO 4217 monetary amount — integer minor units + `text(3)` currency code	`lib/money.value`
`percentage`	Percentage value stored as `decimal(7,4)`	`lib/percentage.value`
`geospatial`	WGS84 coordinate pair — latitude and longitude as `decimal(10,7)`	`lib/geospatial.value`

# Using standard library value types in an entity
entity RoomSessionFee
  "Fee schedule for a room session"

  Schedule1Amount: money "The schedule 1 fee amount"
  CCSPercentage: percentage "The CCS entitlement percentage"
end

entity Centre
  "A childcare centre"

  Name: name "Centre name"
  Location: geospatial, optional "Geographic coordinates"
end

Union Types

Union types represent values with multiple possible shapes. The generator selects the appropriate variant based on infrastructure configuration.

Type	Description	Variants	Library file
`image`	Binary image — inline or external reference	`Embedded`, `Reference`	`lib/image.union`
`document`	Binary document — inline or external reference	`Embedded`, `Reference`	`lib/document.union`

# Using union types in an entity
entity Child
  "A child enrolled at a centre"

  FirstName: name "First name"
  Image: image, optional "Child's photo"
end

entity CertificateSupportingEvidenceDocument
  "A supporting document for an ACCS certificate"

  Document: document "The attached evidence document"
end

The Embedded variant stores binary data directly in the data store (supported by SQL Server). The Reference variant stores a storage key pointing to an external blob store. Infrastructure rules determine which variant is used at generation time.

Defining Your Own Types

Value Objects (`.value`)

User-defined immutable value objects composed of primitives:

value DateRange
  "A period between two dates"

  Start: date "Start of the range"
  End: date "End of the range (inclusive)"
end

Union Types (`.union`)

User-defined discriminated unions with two or more named variants:

union ContactMethod
  "How to contact a person"

  variant Email
    Address: email "Email address"
  end

  variant Phone
    Number: text(20) "Phone number"
    Extension: text(10), optional "Extension"
  end
end

Field Modifiers

Modifier	Syntax	Meaning
Optional	`, optional`	Field may be null/absent
Default value	`, default(value)`	Value used when not supplied

entity Booking
  "A planned attendance"

  Status: BookingStatus, default(Planned) "Current state"
  Notes: text(500), optional "Free text notes"
  IsActive: boolean, default(true) "Whether the booking is active"
end

The `id` Type

id is a shorthand for a generated unique identifier used exclusively in .key files. It implies guid, generated — the field is a GUID and is automatically assigned on creation.

key Child
  ChildId: id
end

Both forms are equivalent; id is preferred in new files:

# equivalent (older style)
key Child
  ChildId: guid, generated
end

Implementation Mapping

DSL Type	C#	SQL Server	SQLite
`text`	`string`	`nvarchar(max)`	`TEXT`
`text(N)`	`string`	`nvarchar(N)`	`TEXT`
`integer`	`int`	`int`	`INTEGER`
`long`	`long`	`bigint`	`INTEGER`
`decimal(P,S)`	`decimal`	`decimal(P,S)`	`NUMERIC`
`boolean`	`bool`	`bit`	`INTEGER`
`date`	`DateOnly`	`date`	`TEXT`
`time`	`TimeOnly`	`time`	`TEXT`
`datetime`	`DateTime`	`datetime2`	`TEXT`
`guid`	`Guid`	`uniqueidentifier`	`TEXT`
`name`	`string`	`nvarchar(100)`	`TEXT`
`binary`	`byte[]`	`varbinary(max)`	`BLOB`
`id`	`Guid`	`uniqueidentifier`	`TEXT`
`email`	`string`	`nvarchar(254)`	`TEXT`
`url`	`string`	`nvarchar(2048)`	`TEXT`
`money`	`Money` (value object)	two columns: `bigint` + `char(3)`	two columns
`percentage`	`Percentage` (value object)	`decimal(7,4)`	`NUMERIC`
`geospatial`	`Geospatial` (value object)	two columns: `decimal(10,7)` × 2	two columns
`image`	`Image` (union)	variant-dependent	variant-dependent
`document`	`Document` (union)	variant-dependent	variant-dependent

Data Types

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