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* Improve Filter Syntax documentaion / navigation * update links and missing diagrams * rename legacy prefix to shortcut prefix * Update editions/tw5.com/tiddlers/filters/Filter Operators.tid Co-authored-by: yaisog <m@rcuswinter.de> * Update editions/tw5.com/tiddlers/filters/syntax/And Filter Run Prefix.tid Co-authored-by: yaisog <m@rcuswinter.de> * Update editions/tw5.com/tiddlers/filters/syntax/Sort Filter Run Prefix.tid Co-authored-by: yaisog <m@rcuswinter.de> * Update editions/tw5.com/tiddlers/filters/syntax/Sort Filter Run Prefix.tid Co-authored-by: yaisog <m@rcuswinter.de> * Update editions/tw5.com/tiddlers/filters/syntax/Sort Filter Run Prefix.tid Co-authored-by: yaisog <m@rcuswinter.de> * Update editions/tw5.com/tiddlers/filters/syntax/Cascade Filter Run Prefix.tid Co-authored-by: yaisog <m@rcuswinter.de> * Update editions/tw5.com/tiddlers/filters/syntax/And Filter Run Prefix.tid Co-authored-by: yaisog <m@rcuswinter.de> * add most changes a suggested by yaisog * fix copy / paste from-version * replace operand with parameter in the docs * fix typo * fix typos and improve railroad diagrams consistency * move "new from version" info for filter run prefixes below the table * fix typo transclusion and substitution * Move Filters tiddler to the top level in the TOC * wip-breadcrumbs * breadcrumbs & breadcrumbsList macro final * remove files that do not belong to this PR * restore release banner * add simple / story mode to breadcrumbs * .breadcrumbs macro update comments * new breadcrumbs CSS, woks with small screens * make CSS configurable using hidden-settings * improve CSS fro small screens * remove the initial: recursiveParentTag macro * improve location info for breadcrumbs nav. add "alt-text" for Edge ::after element * breadcrumbs add mode=field * bc add initial docs * breadcrumbsField will also respect the story ordering * add configurable global filterMode setting * improve arrow CSS for browser zooming * add bc links use bc-caption if caption field is non-empty * breadcrumbs improve comments * breadcrumbs aria-lable uses caption if there is one * breadcrumbs improve documentation * breadcrumbs improve docs for sort param * fix showArrows docs * remove .bc-link aria-label .. it's not needed if caption is resolved properly * use subfilter instead of enlist to evaluate the "excluded" variable. Be consistent with toc-macros * remove breadcrumbs macros - they have their own PR now * resolve conflict * add back doc-macros tiddler * integrate :then filter run prefix * remove .breadcrumbs macros and their config tiddlers * fix typos as requested --------- Co-authored-by: yaisog <m@rcuswinter.de>
33 lines
1.6 KiB
Plaintext
33 lines
1.6 KiB
Plaintext
created: 20190802113703788
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modified: 20230711082337975
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tags: Filters
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title: Conditional Operators
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type: text/vnd.tiddlywiki
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<<.from-version "5.1.20">> The conditional filter operators allow ''if-then-else'' logic to be expressed within filters.
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The foundation is the convention that an empty list can be used to represent the Boolean value <<.value false>> and a list with at one (or more) entries to represent <<.value true>>.
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The conditional operators are:
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* [[then Operator]] replaces any input values with a constant string. For example:
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** <<.inline-operator-example "[[HelloThere]is[missing]then[FOO]]">>
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** <<.inline-operator-example "[[Missing Tiddler]is[missing]then[FOO]]">>
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* [[else Operator]] if the title list is empty then returns a constant string, otherwise returns the original title list
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** <<.inline-operator-example "[[HelloThere]is[tiddler]else[BAR]]">>
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** <<.inline-operator-example "[[Missing Tiddler]is[tiddler]else[BAR]]">>
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These operators can be combined. For example:
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<<.operator-example 1 "[[New Tiddler]is[missing]then[I am missing]else[No I am not missing]]">>
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The <<.olink else>> operator can be used to apply a defaults for missing values. In this example, we take advantage of the fact that the <<.olink get>> operator returns an empty list if the field or tiddler does not exist:
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<<.operator-example 2 "[[HelloThere]get[custom-field]else[default-value]]">>
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''Filter Run Prefixes''
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The [[:then|Then Filter Run Prefix]] and [[:else|Else Filter Run Prefix]] named filter run prefixes serve a similar purpose as the conditional operators.
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Also see: [[Named Filter Run Prefix]]
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