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List Property

Stores an ordered list of items where duplicates are allowed.

See properties page to see which property types it can contain. Property definitions need to be required and values can thus not be null.

  • Kotlin Definition: ListDefinition<T> T is for type of value definition
  • Kotlin Value: List
  • Maryk Yaml Definition: List

Usage options

Section titled “Usage options”
  • Value

Validation Options

Section titled “Validation Options”
  • required - default true
  • final - default false
  • minSize - default unset. Minimum size of list
  • maxSize - default unset. Maximum size of list

Other options

Section titled “Other options”
  • default - the default value to be used if value was not set.
  • valueDefinition - definition of values contained

Examples

Section titled “Examples”

Example of a List property definition for use within a Model

val names by list(
    index = 1u,
    required = false,
    final = true,
    valueDefinition = StringDefinition()
)

Example of a separate List property definition

val def = ListDefinition(
    required = false,
    final = true,
    valueDefinition = StringDefinition()
)

Operations

Section titled “Operations”

List can be applied with List operations through ListPropertyChange to check or change their contents. It can be defined with a set with addValuesToEnd or a list with deleteValues. It can also operate with the value index by a map with addValuesAtIndex or a list with deleteAtIndex.

The current value can be compared against valueToCompare

Example on a model with a list containing strings.

ListChange(
    Model { listOfStrings::ref }.change(
        addValuesToEnd = listOf("three", "four"),
        deleteValues = listOf("one", "two")
    )
)

Example with indexed operations on a model with a list containing strings.

Kotlin:

ListChange(
    Model { listOfStrings::ref }.change(
        addValuesAtIndex = mapOf(
            0 to "three",
            0 to "four"
        ),
        deleteAtIndex = setOf(1, 2)
    )
)

Indexing list values

Section titled “Indexing list values”

List references like refAt(index) and refToAny() (list.*) can be used in filters and changes. They are not indexable in RootDataModel index definitions.

Storage Byte representation

Section titled “Storage Byte representation”

Depends on the specific implementation. The values are stored in their representative byte representation.

Transport Byte representation

Section titled “Transport Byte representation”

Lists can be encoded in 2 ways, normal tag/value pairs and packed mode.

In tag/value pairs the values are encoded with a tag referring to the list and the value as their normal transport byte representation.

Tag value pairs

Section titled “Tag value pairs”

T V T V T V T V T V

  • T = Tag + wiretype
  • V = Value encoded as Length Delimited or Start Group (Until end group)

In Packed encoding multiple values are encoded with one tag representing the specific list and a Length Delimiter. This is only available and is automatically applied for values of BIT_32, BIT_64 or VAR_INT wiretype encoding since the sizes of each item are known.

Packed encoding

Section titled “Packed encoding”

T L V V V V V

  • T = Tag + wiretype of Length Delimited
  • L = VarInt with Length
  • V = Value encoded as BIT_32, BIT_64 or VAR_INT