Primitive Types

This page documents each primitive type available for entity attributes in MDL.

String

Variable-length text data.

String              -- Default length (200)
String(n)           -- Specific length (1 to unlimited)
String(unlimited)   -- No length limit

Examples:

Name: String(200)
Description: String(unlimited)
Code: String(10)

Default value format:

Name: String(200) DEFAULT 'Unknown'
Code: String(10) DEFAULT ''

Integer

32-bit signed integer.

Integer

Range: -2,147,483,648 to 2,147,483,647

Quantity: Integer
Age: Integer DEFAULT 0
Priority: Integer NOT NULL DEFAULT 1

Long

64-bit signed integer.

Long

Range: -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807

FileSize: Long
TotalCount: Long DEFAULT 0

Decimal

High-precision decimal number with up to 20 digits total.

Decimal

Price: Decimal
Amount: Decimal DEFAULT 0
TaxRate: Decimal DEFAULT 0.21

Boolean

True/false value. Boolean attributes must have a DEFAULT value (enforced by Mendix Studio Pro).

Boolean DEFAULT TRUE
Boolean DEFAULT FALSE

IsActive: Boolean DEFAULT TRUE
Enabled: Boolean DEFAULT TRUE
Deleted: Boolean DEFAULT FALSE

DateTime

Date and time stored as a UTC timestamp.

DateTime

CreatedAt: DateTime
ModifiedAt: DateTime
ScheduledFor: DateTime

DateTime values include both date and time components. For date-only display, use Date instead.

Date

Date only (no time component). Internally stored as DateTime in Mendix, but the UI only shows the date portion.

Date

BirthDate: Date
ExpiryDate: Date

AutoNumber

Auto-incrementing integer, typically used for human-readable identifiers. The DEFAULT value specifies the starting number.

AutoNumber

OrderId: AutoNumber NOT NULL UNIQUE DEFAULT 1
CustomerId: AutoNumber

AutoNumber attributes automatically receive the next value on object creation. They are typically combined with NOT NULL and UNIQUE constraints.

Binary

Binary data for files, images, and other non-text content.

Binary

ProfileImage: Binary
Document: Binary
Thumbnail: Binary

File metadata (name, size, MIME type) is stored separately by Mendix. Maximum size is configurable per attribute.

HashedString

Securely hashed string, used for password storage. Values are one-way hashed and cannot be retrieved – comparison is done by hashing the input and comparing hashes.

HashedString

Password: HashedString

Enumeration Reference

References an enumeration type defined with CREATE ENUMERATION. See Enumerations for details.

Enumeration(<Module.EnumerationName>)

Status: Enumeration(Sales.OrderStatus)
Priority: Enumeration(Core.Priority) DEFAULT Core.Priority.Normal
Type: Enumeration(MyModule.ItemType) NOT NULL