FEEL Engine Type Handling
This documentation covers supported types of variable values when used in a FEEL expression and supported output types.
In DMN, when defining a typeRef
attribute on a Variable, Input or Output element, the
DMN Engine tries to convert the result value of the corresponding Literal Expression,
Input Expression or the Output Entry. When no typeRef
attribute is specified, the DMN
Engine passes the return value of the FEEL Engine directly without any conversion. Please see the
documentation about Supported Data Types in DMN to learn more about the typeRef
attribute.
The FEEL Engine might support more types than listed below. However, this page defines which of the types are known for being…
- …well integrable in Camunda Platform
- …covered by automated tests
Supported Variable Value Types
The variable value types listed in this section can be handled by the FEEL Engine when passing.
Java Native Types
java.lang.String
java.lang.Float
java.lang.Double
java.lang.Integer
java.lang.Long
java.lang.Boolean
java.util.Date
java.util.Map
java.util.List
Spin Types
org.camunda.spin.json.SpinJsonNode
org.camunda.spin.xml.SpinXmlElement
For more information about the Camunda Spin integration, please see the documentation about FEEL Engine Spin Integration.
Return Types
The table displays:
- Which return value of a FEEL Expression maps to which Java type
- Which Camunda Platform specific variable type is assigned for the respective Java type
FEEL Expression Example | FEEL Engine Return Type | Camunda Variable Type |
---|---|---|
null |
null |
null |
"foo" |
java.lang.String |
string |
3.1415 |
java.lang.Double |
double |
3 |
java.lang.Long |
long |
true |
java.lang.Boolean |
boolean |
time("11:45:30") |
java.time.LocalTime |
object |
time("11:45:30+02:00") time("10:31:10@Europe/Paris")
|
org.camunda.feel.syntaxtree.ZonedTime |
object |
date("2017-03-10") |
java.time.LocalDate |
object |
date and time("2019-08-12T22:22:22") |
java.time.LocalDateTime |
object |
date and time("2019-08-12T22:22:22+02:00") date and time("2019-08-12T22:22:22@Europe/Berlin")
|
java.time.ZonedDateTime |
object |
duration("P4D") |
java.time.Duration |
object |
duration("P1Y6M") |
java.time.Period |
object |
{ "foo": "bar" } |
java.util.Map * |
object |
[ "foo", "bar", "baz" ] |
java.util.List * |
object |
* Since the FEEL Engine is based on the Scala Library, a Scala-specific implementation type for
Map
and List
is used