MarkLogic 9 Product Documentation

es:optional

es:optional(
   $instance as map:map,
   $key-name as xs:string,
   $key-value as item()?
) as map:map

Summary

This function is deprecated and will not be supported in MarkLogic 11.
Add a key-value pair to a map, if the value exists, and return the modified input map. This function is meant for use in code generated by Entity Services.

Usage Notes

This function is included for use within the modules that Entity Services generates for manipulating instance data. It is identical to map:with except map:with inserts a key with a null value in the case of an empty value. This function leaves the map unmodified if there is no value.

This function returns the original instance, with the key-value pair added.

See Also

• Creating and Managing Models in the Entity Services Developer's Guide.

Example

xquery version "1.0-ml";
import module namespace es = "http://marklogic.com/entity-services"
    at "/MarkLogic/entity-services/entity-services.xqy";

json:object() =>es:optional("a", "value")
              =>es:optional("missing", ())

(: returns an object with one key/value pair, {"a", "value"} :)