7.2.2. Inserting expressions

            JSONInsertExpr ::= "insert" "json" ExprSingle "into" ExprSingle ("at" "position" ExprSingle)?
                             | "insert" "json" PairConstructor ("," Pair Constructor)* "into" ExprSingle

(for explanatory purposes, suboperands are replaced with a variable containing the result of their evaluation)

The second variant corresponds to the insertion of a statically known number of pairs:

insert json "foo" : "bar", "bar" : "foo" into $o

is defined as being equivalent to:

insert json { "foo" : "bar", "bar" : "foo" } into $o

Inserting expressions are available in two flavors (object insertion, array insertion):

insert json $p into $o
$o must be an object. Otherwise, jerr:JNUP0008 is raised.
$p must be a sequence of objects. Otherwise, jerr:JNUP0019 is raised.
$o is post-processed by invoking jn:object, which results in a single object containing all pairs to insert. In particular, jerr:JNDY0003 is raised upon a pair collision.
Makes a copy $p and creates the update primitive jupd:insert-into-object($o, $p)
insert json $c into $a at position $i
$a must be an array. Otherwise, jerr:JNUP0008 is raised.
$i is atomized and cast to xs:integer (jerr:JNUP0007 is raised upon failure).
Makes a copy of all items in $c and creates the update primitive jupd:insert-into-array($a, $i, $c)

Example 7.2. Inserting into an array or an object

              insert json (1, 2, 3) into $a at position 3
              insert json { "foo": 3, "bar":4 } into $o