mdl-entities

name	mdl-entities
description	Complete MDL syntax reference for creating entities, attributes, associations, enumerations, and view entities
compatibility	opencode

Domain model syntax expert for Mendix MDL. Covers persistent entities, non-persistent entities, view entities, attributes, associations, enumerations, and indexes.

Complete syntax reference for creating entities, attributes, and associations in MDL.

- Create persistent, non-persistent, or view entities - Define attributes, associations, or enumerations - Set up entity inheritance (generalization) - Create domain model from requirements

<entity_types>

Type	Keyword	Stored in DB	Use Case
Persistent	create persistent entity	Yes	Business data
Non-Persistent	create non-persistent entity	No	Temporary/view data
View	create view entity	No (OQL query)	Aggregated/computed data
</entity_types>

<persistent_entity>

/**
 * Customer entity for storing customer data
 */
create persistent entity Module.Customer (
  -- String attributes
  Name: string(100) not null,
  Email: string(200),
  Code: string(20) unique,

  -- Numeric attributes
  Age: integer,
  CreditLimit: decimal,

  -- Boolean
  IsActive: boolean default true,

  -- Date/Time
  CreatedDate: datetime,
  BirthDate: date,

  -- Enumeration
  status: Module.CustomerStatus default Active,

  -- Auto-number
  CustomerNumber: autonumber
);
/

</persistent_entity>

<non_persistent_entity> Used for temporary data, form parameters, or calculated values.

/**
 * Search parameters for customer search form
 */
create non-persistent entity Module.CustomerSearchParams (
  SearchName: string(100),
  SearchEmail: string(200),
  MinCreditLimit: decimal,
  IncludeInactive: boolean default false
);
/

</non_persistent_entity>

<attribute_types>

Type	Syntax	Example
String	Name: string(length)	Name: string(100)
Integer	Name: integer	count: integer
Long	Name: long	BigNumber: long
Decimal	Name: decimal	Amount: decimal
Boolean	Name: boolean	IsActive: boolean
DateTime	Name: datetime	CreatedAt: datetime
Date	Name: date	BirthDate: date
Enumeration	Name: Module.EnumName	status: Module.Status
AutoNumber	Name: autonumber	Code: autonumber
Binary	Name: binary	FileData: binary
Hashed String	Name: hashedstring	password: hashedstring
</attribute_types>

<attribute_modifiers>

Modifier	Meaning	Example
not null	Required field	Name: string(100) not null
unique	Unique constraint	Code: string(20) unique
default value	Default value	IsActive: boolean default true

Note: Boolean attributes auto-default to false when no default is specified. </attribute_modifiers>

**CRITICAL: EXTENDS goes BEFORE the opening parenthesis, not after!**

/**
 * Base entity
 */
create persistent entity Module.Person (
  PersonName: string(100) not null,
  Email: string(200)
);
/

/**
 * Customer extends Person - EXTENDS before (
 */
create persistent entity Module.Customer extends Module.Person (
  CustomerCode: string(20),
  CreditLimit: decimal
);
/

Common parent entities for file/image storage:

-- Image entity (inherits Name, Size, Contents, thumbnail)
create persistent entity Module.ProductPhoto extends System.Image (
  PhotoCaption: string(200),
  SortOrder: integer default 0
);

-- File document (inherits Name, Size, Contents)
create persistent entity Module.Attachment extends System.FileDocument (
  AttachmentDescription: string(500)
);

Wrong (parse error):

-- EXTENDS after ) = parse error!
create persistent entity Module.Photo (
  PhotoCaption: string(200)
) extends System.Image;

### Reference (Many-to-One)

/**
 * Order belongs to one Customer
 */
create association Module.Order_Customer (
  PARENT Module.Customer,
  CHILD Module.Order
);
/

Reference Set (Many-to-Many)

/**
 * Product can be in many Categories
 * Category can have many Products
 */
create association Module.Product_Category (
  PARENT Module.Category as reference set,
  CHILD Module.Product
);
/

Association with Delete Behavior

/**
 * Delete orders when customer is deleted
 */
create association Module.Order_Customer (
  PARENT Module.Customer,
  CHILD Module.Order,
  delete PARENT cascade  -- Delete orders when customer deleted
);
/

Delete behaviors:

• delete PARENT cascade - Delete children when parent deleted
• delete PARENT prevent - Prevent deletion if children exist
• delete CHILD cascade - Delete parent when last child deleted

```mdl /** * Order status values */ create enumeration Module.OrderStatus ( Draft = 'Draft', Pending = 'Pending', Approved = 'Approved', Shipped = 'Shipped', Delivered = 'Delivered', Cancelled = 'Cancelled' ); / ```

<view_entity>

/**
 * Monthly sales summary by customer
 */
create view entity Module.CustomerSalesSummary (
  CustomerName: string(100),
  TotalOrders: integer,
  TotalAmount: decimal,
  LastOrderDate: datetime
)
as
  select
    c.Name as CustomerName,
    count(o.OrderID) as TotalOrders,
    sum(o.Amount) as TotalAmount,
    max(o.OrderDate) as LastOrderDate
  from Module.Customer c
  left join c/Module.Order_Customer/Module.Order o
  GROUP by c.Name;
/

</view_entity>

<entity_with_index>

/**
 * Product with search index
 */
create persistent entity Module.Product (
  Code: string(20) not null,
  Name: string(100) not null,
  Category: string(50),
  Price: decimal
)
index idx_product_code on (Code)
index idx_product_category on (Category);
/

</entity_with_index>

<complete_domain_model_example>

-- Enumeration
create enumeration Shop.OrderStatus (
  Draft = 'Draft',
  Confirmed = 'Confirmed',
  Shipped = 'Shipped',
  Delivered = 'Delivered'
);
/

-- Customer entity
create persistent entity Shop.Customer (
  Name: string(100) not null,
  Email: string(200) not null unique,
  Phone: string(20),
  IsActive: boolean default true,
  CreatedDate: datetime
);
/

-- Product entity
create persistent entity Shop.Product (
  Code: string(20) not null unique,
  Name: string(100) not null,
  description: string(500),
  Price: decimal not null,
  Stock: integer default 0,
  IsAvailable: boolean default true
);
/

-- Order entity
create persistent entity Shop.Order (
  OrderNumber: autonumber,
  OrderDate: datetime not null,
  status: Shop.OrderStatus default Draft,
  TotalAmount: decimal,
  Notes: string(500)
);
/

-- Order line entity
create persistent entity Shop.OrderLine (
  Quantity: integer not null,
  UnitPrice: decimal not null,
  LineTotal: decimal
);
/

-- Associations
create association Shop.Order_Customer (
  PARENT Shop.Customer,
  CHILD Shop.Order
);
/

create association Shop.OrderLine_Order (
  PARENT Shop.Order,
  CHILD Shop.OrderLine,
  delete PARENT cascade
);
/

create association Shop.OrderLine_Product (
  PARENT Shop.Product,
  CHILD Shop.OrderLine
);
/

</complete_domain_model_example>

<quick_reference>

Entity Creation

create persistent entity Module.Name (attributes);
create non-persistent entity Module.Name (attributes);
create view entity Module.Name (attributes) as select ...;

Attribute Syntax

attributename: type [(length)] [not null] [unique] [default value]

Association Syntax

create association Module.Name (
  PARENT Module.ParentEntity [as reference set],
  CHILD Module.ChildEntity
  [, delete PARENT cascade|prevent]
);

Enumeration Syntax

create enumeration Module.Name (
  Value1 = 'Caption1',
  Value2 = 'Caption2'
);

</quick_reference>

<output_rules>Output MDL code only in code blocks. Keep explanations concise.</output_rules>