created: 20150203140000000
modified: 20230325163543621
tags: [[getindex Operator]] [[Operator Examples]]
title: getindex Operator (Examples)
type: text/vnd.tiddlywiki

<<.operator-example 1 "[[$:/palettes/Vanilla]getindex[background]]" "returns the value of property <<.value background>> of the [[DataTiddler|DataTiddlers]] [[$:/palettes/Vanilla]]">>

<<.operator-example 2 "[all[shadows+tiddlers]tag[$:/tags/Palette]getindex[background]]" "returns all background colors defined in any of the ColourPalettes (notice the duplicates in the resulting list)">>

<<.tip """If a data tiddler contains a property with an empty value, the empty string is not appended to the results.""">>

<<.operator-example 3 "[[ListopsData]getindex[DataIndex]]" "the empty value of the property <<.field ~DataIndex>> in [[ListopsData]] is not returned by the <<.olink getindex>> operator">>

<<.operator-example 4 "[[ListopsData]has:index[DataIndex]] :map[getindex[DataIndex]]" "also returns the empty string">>
The above example works by first checking if the input title has the property <<.field ~DataIndex>> and then using the [[Map Filter Run Prefix]] to replace the title with their value of that property. If the input tiddler does not have the property, an empty <<.em selection>> is returned. The subsequent [[Map Filter Run Prefix]] outputs an empty <<.em string>> when its run returns an empty [[selection|Title Selection]] (because the property is empty).

<<.operator-example 5 "[[$:/palettes/Vanilla]indexes[]] :filter[[$:/palettes/Vanilla]getindex<currentTiddler>count[]compare:number:eq[0]]" "returns those colors in [[$:/palettes/Vanilla]] which are defined, but have no value assigned">>
In the above example, <<.olink count>> is used to check if <<.olink getindex>> returns a result (i.e. the corresponding property has a value) or not.