MarkLogic 9 Product Documentationfn:exactly-one
fn:exactly-one( $arg as item()* ) as item()
Summary
Returns $arg if it contains exactly one item. Otherwise, raises an error [err:FORG0005].
For detailed type semantics, see Section 7.2.16 The fn:zero-or-one, fn:one-or-more, and fn:exactly-one functions[FS].
| Parameters | |
|---|---|
| arg | The sequence of items. |
Example
fn:exactly-one(("hello"))
=> "hello"
fn:exactly-one(("hello", "goodbye"))
=> XDMP-NOTONEITEM exception (because there are 2 items)
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