Entities and fields

An entity is a kind of record your application stores. A field is one value on that record.

Entity Product
    Field Name Text(120)
    Field Price Money
    Field Active Boolean = True
    Field Launched Date?
    Field Category Enum(Hardware, Software, Service) = Hardware

Names

Entity and field names start with a letter and contain only letters and digits. Use PascalCase: SalesOrder, DueDate. The app turns them into readable labels (Sales order, Due date), and the API uses camelCase (dueDate) in JSON and kebab-case plurals in routes (/api/v1/sales-orders).

Types

Type	Stores	Notes
Text	text of any length	Shown as a multi-line box
Text(n)	text of at most n characters	Up to 255 is a single line
Boolean	true or false	A switch in forms
Int	a whole number	32-bit
Decimal	an exact decimal number	Stored without floating-point rounding
Money	an exact decimal amount	Shown with two decimals
Date	a calendar date	JSON "2026-01-31"
DateTime	a moment in time	JSON with a time zone; stored in UTC
Time	a time of day	JSON "09:30"
Email	an email address	Format checked
Phone	a phone number	Digits, spaces, + ( ) - .; at least three digits
Url	a web address	Must start with http:// or https://
Enum(A, B, C)	one of the listed names	Stored by name
-> Entity	a reference to another record	See Relationships

Required and optional

Every field is required unless its type ends with ?:

Field Notes Text(2000)?      # may be empty
Field Title Text(200)        # required, and must not be blank

The server rejects a create request that omits a required field, and rejects null or blank text for one. The app marks optional fields and checks required ones before submitting.

Defaults

A default fills a field when a create request leaves it out, and pre-fills new-record forms:

Field Active Boolean = True
Field Quantity Int = 1
Field Price Money = 9.95
Field Status Enum(Open, Closed) = Open
Field Country Text(2) = "NL"
Field Opens Time = "09:00"

Defaults must match the field's type: True or False for booleans, a number for numbers, an option name for enums, and quoted text for text-like types. The compiler checks formats too, so Field Contact Email = "nobody" is an error.

Enums

Field Priority Enum(Low, Normal, High) = Normal

Options are names that start with a letter. The API accepts and returns the name ("High"). You may give options numbers, Enum(Low = 1, High = 2); the API then also accepts the number on input, but records always store and return the name. Adding options later is a safe migration; removing one is destructive.

Rules

Types check one value at a time. A rule checks the record as a whole:

Entity Booking
    Field Guests Int
    Field StartsOn Date
    Field EndsOn Date?
    Field Status Enum(Requested, Confirmed, Cancelled) = Requested
    Field CancelReason Text(500)?

    Rule Guests > 0 "Book for at least one guest"
    Rule Status != Requested Or StartsOn >= Today "Requests cannot start in the past"
    Rule EndsOn >= StartsOn "The stay must end after it starts"
    Rule Status != Cancelled Or CancelReason != Null "Say why the booking was cancelled"

The server checks every rule when a record is created or updated. If a condition is false, the save is refused and the app shows the message next to the first field the rule names. A comparison with an empty field does not fail: EndsOn >= StartsOn holds while EndsOn is empty. See Rules for every condition you can write.

Rules apply to saves, not to records already stored. Rules that use Today or Now also apply when an old record is edited later, which is why the date rule above only checks open requests.

System fields

Every record also has fields you do not declare:

Field	Meaning
id	Opaque identifier. The app never shows it.
createdOn, modifiedOn	UTC timestamps
createdBy, modifiedBy	The account that made the change, when signed in

Deleting a record is a soft delete: the record disappears from the API and the app, and its row keeps deletedOn and deletedBy in the database. You cannot declare fields with these names.