SetWidget

15th March 2018 at 4:54pm

Introduction

The set variable widget assigns a value to a specified variable. The new value of the variable is available to the content within the set variable widget.

Content and Attributes

The content of the <$set> widget is the scope for the value assigned to the variable.

Attribute	Description
name	The name of the variable to assign (defaults to "currentTiddler")
value	The value to assign to the variable if the filter is missing or not empty
tiddler	New in: 5.1.15 Optional title of the tiddler from which to read the value
subtiddler	New in: 5.1.16 Optionally specifies the title of a subtiddler within a plugin tiddler identified by the tiddler attribute
field	New in: 5.1.15 Optional field of the tiddler from which to read the value (only used if tiddler is used)
index	New in: 5.1.15 Optional index of the tiddler from which to read the value (only used if tiddler is used)
filter	An optional filter to be evaluated and assigned to the variable (see below)
select	New in: 5.1.14 An optional zero-based index of the item to return from the filter output (see below)
emptyValue	The value to assign to the variable if the specified value is missing or empty (see below)

If the value of your variable is enclosed in double square brackets this might indicate that you are returning a list of values from the filter. To use a single title from the filter output without the double square brackets see Filtered Item Variable Assignment below.

Simple Variable Assignment

The simplest way of using set variable widget assigns a string to a variable. The following example assigns a literal string

<$set name="myVariable" value="Some text">
<$text text=<<myVariable>>/>
</$set>

Both the name and value attributes can be transcluded. For example:

<$set name=<<anotherVariable>> value={{template!!text}}>
<$text text=<<myVariable>>/>
</$set>

Conditional Variable Assignment

This form of the set variable widget chooses one of two specified values according to whether a filter evaluates to an empty list. Here's an example that sets a variable according to whether the current tiddler is called "myMagicTitle":

<$set name="myVariable" filter="[all[current]field:title[myMagicTitle]]" value="It's magic" emptyValue="It's not magic">
<$text text=<<myVariable>>/>
</$set>

Filtered List Variable Assignment

This form of the set variable widget evaluates the filter and assigns the result to the variable as a space-separated list (using double square brackets for titles containing spaces).

<$set name="myVariable" filter="[tag[HelloThere]]">
<$text text=<<myVariable>>/>
</$set>

Filtered Item Variable Assignment

New in: 5.1.14 This form of the set variable widget evaluates the filter and assigns the specified result to the variable as a single item (ie, not using double square brackets for titles containing spaces).

<$set name="myVariable" filter="[tag[HelloThere]]" select="0">
<$text text=<<myVariable>>/>
</$set>

Transcluded Variable Assignment

New in: 5.1.15 This form of the set variable widget obtains the value to assign to the variable from a value in a tiddler field or index. For example:

<$set name="myVariable" tiddler="HelloThere" field="text">
<$text text=<<myVariable>>/>
</$set>

The example above could also be written as <$set name="myVariable" value={{HelloThere!!text}}>. The advantage of using the tiddler attribute is that the tiddler title and field or index can themselves be computed. For example:

<$set name="myVariable" tiddler=<<myTiddler>> field={{$:/currentField}}>
<$text text=<<myVariable>>/>
</$set>