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TiddlyWiki5/editions/tw5.com/tiddlers/filters/jsonindexes.tid
Mario Pietsch a49436160d
Improve Filter Syntax documentation (#7368)
* 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>
2024-02-14 17:20:32 +01:00

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created: 20220611104737314
modified: 20220611104737314
tags: [[Filter Operators]] [[JSON Operators]]
title: jsonindexes Operator
caption: jsonindexes
op-purpose: retrieve the value of a property from JSON strings
op-input: a selection of JSON strings
op-parameter: one or more indexes of the property to retrieve
op-output: the values of each of the retrieved properties
<<.from-version "5.2.4">> See [[JSON in TiddlyWiki]] for background.
The <<.op jsonindexes>> operator is used to retrieve the property names of JSON objects or the index names of JSON arrays. See also the following related operators:
* <<.olink jsonget>> to retrieve the values of a property in JSON data
* <<.olink jsontype>> to retrieve the type of a JSON value
* <<.olink jsonextract>> to retrieve a JSON value as a string of JSON
Properties within a JSON object are identified by a sequence of indexes. In the following example, the value at `[a]` is `one`, and the value at `[d][f][0]` is `five`.
```
{
"a": "one",
"b": "",
"c": "three",
"d": {
"e": "four",
"f": [
"five",
"six",
true,
false,
null
],
"g": {
"x": "max",
"y": "may",
"z": "maize"
}
}
}
```
The following examples assume that this JSON data is contained in a variable called `jsondata`.
The <<.op jsonindexes>> operator uses multiple parameters to specify the indexes of the property to retrieve:
```
[<jsondata>jsonindexes[d],[f]] --> "0", "1", "2", "3", "4"
[<jsondata>jsonindexes[d],[g]] --> "x", "y", "z"
```
Indexes can be dynamically composed from variables and transclusions:
```
[<jsondata>jsonindexes<variable>,{!!field}]
```
Retrieving the indexes of JSON properties that are not objects or arrays will return nothing.
A subtlety is that the special case of a single blank parameter is used to identify the root object. Thus:
```
[<jsondata>jsonindexes[]] --> "a", "b", "c", "d"
```