Property Values

propertyValues sets values on an instance's members by nesting, mirroring the shape of the type. It is the alternative to initializers, which addresses the same variables by path — use whichever reads better for the model at hand, or both.

Nesting mirrors the type

Each key is a member browse name, alias-qualified like everywhere else in the DSL. A value is either the value to assign, or a nested mapping addressing that member's own children:

Values by nesting
instances:
  - browseName: Pump1
    typeDefinition: PumpType
    organizedBy: /ua:Objects
    propertyValues:
      di:Manufacturer: Sterfive
      ParameterSet:
        Pressure: 4.2
        Flow: 120.0

A key that names no member of the enclosing node is an error, not a new node — so a misspelling is reported rather than silently creating something the type never declared.

`$value` — a variable that also has children

A variable with sub-properties of its own needs a way to say "this one, not a child of it". The reserved key $value does that:

A value alongside its own sub-properties
instances:
  - browseName: Pump2
    typeDefinition: PumpType
    organizedBy: /ua:Objects
    propertyValues:
      Level:
        # the variable's OWN value, alongside its sub-properties
        $value: 42.0
        ua:EngineeringUnits: "%"
        ua:EURange:
          low: 0.0
          high: 100.0

$value is rejected on an Object — only a Variable has a value to set.

Value literals

Because a mapping normally means "recurse into children", the two structures models most often write inline would be ambiguous. Two shapes are therefore read as values:

Shape	When
`{text, locale?}`	the variable's DataType is LocalizedText
`{low, high}`	the variable's DataType is Range

Inline LocalizedText and Range
instances:
  - browseName: Pump3
    typeDefinition: PumpType
    organizedBy: /ua:Objects
    propertyValues:
      # {text, locale?} on a LocalizedText is a VALUE, not a child named "text"
      di:Manufacturer:
        text: Sterfive
        locale: en
      # {low, high} on a Range is likewise a value
      Level:
        ua:EURange:
          low: 0.0
          high: 250.0

The match is exact and deliberate: {txt: "Sterfive"} is not a LocalizedText with a typo, it is a reference to a child named txt, and you get the usual "cannot find child" error. That is what keeps a typo from being silently swallowed as a value.

Optional members

Assigning a value implies presence here too, at any depth of the tree — the instance does not need to repeat the member under optionals::

An Optional member needs no optionals: entry
instances:
  - browseName: Pump4
    typeDefinition: PumpType
    organizedBy: /ua:Objects
    # no `optionals:` — assigning a value opts MaintenanceNote in
    propertyValues:
      MaintenanceNote: "replace seal at 5000 h"

See Initializing an optional member for the same rule as it applies to initializers:.

Choosing between `propertyValues` and `initializers`

Both write values to existing variables; they differ only in how the target is named.

	`propertyValues`	`initializers`
Addressing	nested, mirrors the type	a browse path per entry
Placement	on the instance	on the instance, or at the document root
Reads well when	setting many values under one parent	setting a few scattered values, or grouping every value in one section

📄 Full working example — property-values.model.yaml

# yaml-language-server: $schema=../../../../schemas/nodeset2.schema.json
#
# Living documentation example for: s67_property-values.md
# Validate: opcua-modeler generate --input property-values.model.yaml
#
namespaceUri: http://example.com/doc-examples/property-values/
namespaces:
  - di
version: 1.0.0

objectTypes:
  - browseName: PumpType
    subtypeOf: di:DeviceType
    components:
      - browseName: ParameterSet
        typeDefinition: ua:FolderType
        components:
          - browseName: Pressure
            dataType: ua:Double
          - browseName: Flow
            dataType: ua:Double
      - browseName: Level
        dataType: ua:Double
        typeDefinition: ua:AnalogUnitRangeType
      - browseName: MaintenanceNote
        dataType: ua:String
        modellingRule: Optional

instances:
  - browseName: Pump1
    typeDefinition: PumpType
    organizedBy: /ua:Objects
    propertyValues:
      di:Manufacturer: Sterfive
      ParameterSet:
        Pressure: 4.2
        Flow: 120.0

  - browseName: Pump2
    typeDefinition: PumpType
    organizedBy: /ua:Objects
    propertyValues:
      Level:
        # the variable's OWN value, alongside its sub-properties
        $value: 42.0
        ua:EngineeringUnits: "%"
        ua:EURange:
          low: 0.0
          high: 100.0

  - browseName: Pump3
    typeDefinition: PumpType
    organizedBy: /ua:Objects
    propertyValues:
      # {text, locale?} on a LocalizedText is a VALUE, not a child named "text"
      di:Manufacturer:
        text: Sterfive
        locale: en
      # {low, high} on a Range is likewise a value
      Level:
        ua:EURange:
          low: 0.0
          high: 250.0

  - browseName: Pump4
    typeDefinition: PumpType
    organizedBy: /ua:Objects
    # no `optionals:` — assigning a value opts MaintenanceNote in
    propertyValues:
      MaintenanceNote: "replace seal at 5000 h"

Nesting mirrors the type​

$value — a variable that also has children​

Value literals​

Optional members​

Choosing between propertyValues and initializers​

Nesting mirrors the type

`$value` — a variable that also has children

Value literals

Optional members

Choosing between `propertyValues` and `initializers`