Type Mapping

This page shows how MDL types correspond to Mendix internal types (BSON storage) and the Go SDK types used by modelsdk-go.

MDL to Backend Type Mapping

MDL Type	BSON `$Type`	Go SDK Type
`String`	`DomainModels$StringAttributeType`	`*StringAttributeType`
`String(n)`	`DomainModels$StringAttributeType` + Length	`*StringAttributeType{Length: n}`
`Integer`	`DomainModels$IntegerAttributeType`	`*IntegerAttributeType`
`Long`	`DomainModels$LongAttributeType`	`*LongAttributeType`
`Decimal`	`DomainModels$DecimalAttributeType`	`*DecimalAttributeType`
`Boolean`	`DomainModels$BooleanAttributeType`	`*BooleanAttributeType`
`DateTime`	`DomainModels$DateTimeAttributeType`	`*DateTimeAttributeType`
`Date`	`DomainModels$DateTimeAttributeType`	`*DateTimeAttributeType`
`AutoNumber`	`DomainModels$AutoNumberAttributeType`	`*AutoNumberAttributeType`
`Binary`	`DomainModels$BinaryAttributeType`	`*BinaryAttributeType`
`Enumeration`	`DomainModels$EnumerationAttributeType`	`*EnumerationAttributeType`
`HashedString`	`DomainModels$HashedStringAttributeType`	`*HashedStringAttributeType`

Note that Date and DateTime both map to the same underlying BSON type. The distinction is handled at the UI layer.

Default values are stored in BSON as StoredValue structures:

MDL Default	BSON Structure
`DEFAULT 'text'`	`Value: {$Type: "DomainModels$StoredValue", DefaultValue: "text"}`
`DEFAULT 123`	`Value: {$Type: "DomainModels$StoredValue", DefaultValue: "123"}`
`DEFAULT TRUE`	`Value: {$Type: "DomainModels$StoredValue", DefaultValue: "true"}`
(calculated)	`Value: {$Type: "DomainModels$CalculatedValue", Microflow: <id>}`

All default values are serialized as strings in the BSON storage, regardless of the attribute type.