Function Usage
In addition to retrieving a field from a Record, we sometimes need to refine which fields
we want to select. Or we may want to return a modified version of a field. To do this, we
rely on functions. The syntax for a function is <function name> <open
parenthesis> <args> <close parenthesis>, where <args> represents one
or more arguments separated by commas. An argument may be a string literal (such as
'hello'
) or a number literal (such as 48
), or could be
a relative or absolute RecordPath (such as ./name
or
/id
). Additionally, we can use functions within a filter. For example, we
could use a RecordPath such as /person[ isEmpty('name') ]/id
to retrieve
the id
field of any person whose name is empty. A listing of functions
that are available and their corresponding documentation can be found below in the
Functions section.