Comments and Documentation

MDL supports three comment styles for annotating scripts and attaching documentation to model elements.

Single-Line Comments

Use -- (SQL style) or // (C style) for single-line comments:

-- This is a single-line comment
LIST MODULES;

// This is also a single-line comment
LIST ENTITIES IN Sales

Everything after the comment marker to the end of the line is ignored.

Multi-Line Comments

Use /* ... */ for comments that span multiple lines:

/* This comment spans
   multiple lines and is useful
   for longer explanations */
CREATE PERSISTENT ENTITY Sales.Customer (
  Name: String(200) NOT NULL
);

Documentation Comments

Use /** ... */ to attach documentation to model elements. Documentation comments are stored in the Mendix model and appear in Studio Pro:

/** Customer entity stores master customer data.
 *  Used by the Sales and Support modules.
 */
@Position(100, 200)
CREATE PERSISTENT ENTITY Sales.Customer (
  /** Unique customer identifier, auto-generated */
  CustomerId: AutoNumber NOT NULL UNIQUE DEFAULT 1,

  /** Full legal name of the customer */
  Name: String(200) NOT NULL,

  /** Primary contact email address */
  Email: String(200) UNIQUE
);

Documentation comments can be placed before:

• Entity definitions (becomes entity documentation)
• Attribute definitions (becomes attribute documentation)
• Enumeration definitions (becomes enumeration documentation)
• Association definitions (becomes association documentation)

Not before an enumeration value or an index: Mendix stores no documentation on a value and no name on an index, so check warns that the text is not kept (MDL-ENUMDOC01, MDL-IDX01). Use an ordinary -- comment for a note there.

Updating Documentation

You can also set documentation on existing entities with ALTER ENTITY:

ALTER ENTITY Sales.Customer
  SET DOCUMENTATION 'Customer master data for the Sales module';