Task Input Expressions
In some tasks, the input to the task needs to be passed to a service being called by the
task, to a user-visible form, or other consumers of the input data.
A TaskInputExpression can be used to do this declaratively.
A TaskInputExpression is a String prefixed with "$input", "$inputRecord", "$ruleScope",
"$state" or "$last" followed by an optional dot-separated hierarchical path,
which can specify either an atomic data value (String, Number) or Record from the
input data. For example, if the Process.state represented in JSON were:
{
orderId:5,
orderItems: [
{name:"Pencils", quantity:3, itemId:2344}
],
orderUser: { name:"Henry Winkle", address:"...", ... }
}
.. and a task specified an
inputField of "orderId" and an inputFieldList of
"orderItems","orderUser", then:
- $input is the value 5
- $inputRecord.orderUser.name is "Henry Winkle"
- $inputRecord.orderItems[0] is the first orderItems Record ({name:"Pencils", ... })
"$ruleScope" can be used to pull values from a ruleScope
ruleContext when configured in Process.ruleScope.
- $ruleScope.property references the ruleContext "property" field
Two others sources of input are "$state" and "$last". The former references the
contents of the Process.state and
the latter the
transient state.
- $state is the full contents of the process state
- $state.orderId is the "orderId" field of the process state (5 from the example above)
- $last is the full output of the previous task executed in the process
- $last.property is the "property" field of the previous task executed in the process
- $last[service].property or $last[ServiceTask].property references the last "ServiceTask"
output in the "property" field
- $ruleScope.property references the ruleScope "property" field
The last two sources of input are "$lastRequest" and "$lastResponse". These are the
objects dsRequest and dsResponse representing the last
ServiceTask, DSFetchTask, DSAddTask, DSUpdateTask or
DSRemoveTask DataSource operation as returned in the
operation's
callback. A common usage would be to reference
$lastResponse.totalRows to know how many rows were returned from a fetch.
Transient state outputs
Most tasks pass the output from the
previous task as their output (i.e. passed
through) making it easy to refer to earlier output without referencing the task type.
Tasks that work with records or interact with the user, however, typically provide
task-specific output as detailed below:
- ServiceTask: the contents of dsResponse.data.
- ScriptTask: the result of
execute() or,
for an asynchronous task, the value passed to
setOutputRecord() or
setOutputData().
- StateTask: the value assigned to the outputField.
- UserTask: the values of the targetForm or targetVM when the task completes.
- AskForValueTask: an object with "value" and "canceled" properties.
- FetchRelatedDataTask: the first fetched record.
- GridFetchDataTask: the contents of dsResponse.data.
- GridTransferSelectedTask: the first transfered record.
- GridSelectRecordsTask: on a select, the set of newly selected records,
even if other records are also selected. On a deselect, the entire set of
de-selected records.
- FetchRelatedDataTask: the first fetched related record.
- FormSaveDataTask: an object with "valuesValid" and "errors" properties.
- FormValidateValuesTask: an object with "valuesValid" and "errors" properties.
- GetPropertiesTask: an object with selected properties and values retrieved.