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.
The content of the <$set> widget is the scope for the value assigned to the variable.
| Attribute | Description |
|---|---|
| name | The name of the variable to assign (defaults to "currentTiddler") |
| value | The value to assign to the variable if the filter is missing or not empty |
| tiddler | New in: 5.1.15 Optional title of the tiddler from which to read the value |
| subtiddler | New in: 5.1.16 Optionally specifies the title of a subtiddler within a plugin tiddler identified by the tiddler attribute |
| field | New in: 5.1.15 Optional field of the tiddler from which to read the value (only used if tiddler is used) |
| index | New in: 5.1.15 Optional index of the tiddler from which to read the value (only used if tiddler is used) |
| filter | An optional filter to be evaluated and assigned to the variable (see below) |
| select | New in: 5.1.14 An optional zero-based index of the item to return from the filter output (see below) |
| emptyValue | The value to assign to the variable if the specified value is missing or empty (see below) |
The simplest way of using set variable widget assigns a string to a variable. The following example assigns a literal string
<$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>>/>
</$set>This form of the set variable widget chooses one of two specified values according to whether a filter evaluates to an empty list. Here's an example that sets a variable according to whether the current tiddler is called "myMagicTitle":
<$set name="myVariable" filter="[all[current]field:title[myMagicTitle]]" value="It's magic" emptyValue="It's not magic">
<$text text=<<myVariable>>/>
</$set>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>>/>
</$set>New in: 5.1.14 This form of the set variable widget evaluates the filter and assigns the specified result to the variable as a single item (ie, not using double square brackets for titles containing spaces).
<$set name="myVariable" filter="[tag[HelloThere]]" select="0">
<$text text=<<myVariable>>/>
</$set>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>