2. Paths
Select source values with paths, indexes, wildcards and explicit starting values.
sUTL · Guide · Reference · Examples
Paths select values from the source, scope, library, or transform itself. The deployed dialect combines a result prefix with a selector:
^returns the first selected value, or null.&returns the complete list of selected values.$starts at the root source.@starts at the caller's scope.^as a selector starts at the current builtin scope.*starts at the transform library.~starts at the root transform.%starts at a value supplied as the first argument.
The first ^ in "^$.name" is the result prefix; $ is the selector.
Map members and list indexes
Given:
{
"person": {"name": "Ada"},
"items": ["zero", "one"]
}
"^$.person.name" returns "Ada", and "^$.items.1" returns "one".
Missing head selections return null.
Wildcards
* selects immediate children:
"&$.people.*.name"
Given two people, this returns both names. ** descends recursively:
"&$.document.**.url"
Use & when a wildcard may select several values. A ^ wildcard deliberately
takes only the first and should not be used where map ordering matters.
Raw paths
% selects from a value constructed inside the transform:
["^%", {"person": {"name": "Fred"}}, "person", "name"]
Result:
"Fred"
The list form can represent selectors that would be awkward in a dotted string.
Paths are forgiving
An inapplicable path component discards that branch. It does not throw. The
full-list form therefore returns [] for no matches, while the head form
returns null.
Historical note
The old v0.3 README used # and ##. Deployed Studio examples and all later
language material use ^ and &; this guide uses the deployed notation.
Try the curated basic path and wildcard examples.
Next: Builtins.
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Source
Adapted from the sUTL source material.