CEL expressions and limitations in DataStage
Use expressions to define conditions, input values, and user variables in an orchestration flow. If a migrated sequence job contains expressions, they must be translated into CEL syntax.
You can access built-in functions and other coding elements through the Expression Builder. The Expression Builder uses CEL (Common Expression Language). For more information about built-in functions, see Functions. For DataStage-specific functions, see DataStage Functions.
Expressions are evaluated in the context of a particular job run in a specific scope. The scope
can be a project, space, or catalog. Use the ctx object to refer to context
properties such as the name and ID of the scope, job, user, and pipeline. Example:
ctx.pipeline.id.
To reference a node in the pipeline, copy the Node ID from that node's properties. You can also
use the tasks object to reference nodes and job results. Components with the
standard output use the results object to store the results of the flow. For
nonstandard outputs, you can also use results to retrieve customized outputs or
variables set as output. When error handling is triggered, the error object can be
used inside the Exception handler.
| Expression Description | CEL | DataStage |
|---|---|---|
| Logical operators | a > b || c < 10 |
a > b OR c < 10 |
| Ternary operator | a > b ? 'A' : 'B' |
IF a > b THEN 'A' ELSE 'B' |
| String concatenation | "prefix-" + parameter + "-suffix" |
"prefix-" : parameter : "-suffix" |
| String starts with | param.startsWith('abc') |
Left(param,3) = 'abc' |
| Substring index | param.indexOf('abc') |
Index(param, 'abc', 1) |
| String replace | param.replace('he', 'we') |
Ereplace(param, "he", "we") |
| String lowercase | param.lowerAscii() |
DownCase(param) |
| Is null | param == null |
IsNull(param) |