¶ Description
Run a pipeline in a "while" loop.
¶ Parameters
¶ Parameters tab
Parameters:
-
Developer mode: activate/deactivate code tab.
-
Pipelines to run inside a loop Select the pipeline to execute each iteration.
-
Optional: global Loop Params Click … to seed the loop with initial Global Parameters. Use key=value rows.
-
Global Parameters to pass to the pipeline (comma-separated) Comma-separated list of GP names to forward to the inner pipeline. (Only these are guaranteed to be passed through.
-
**Loop continues while Returned ErrorLevel "e" is:**JavaScript-style boolean. Defaults to
((e==0) || (e==1)).
You can use:e– the inner pipeline’s last ErrorLevel- Any Global Parameters (including the counter name if enabled)
-
Clear the value of all Global Parameters before running the pipeline Toggle on to start each iteration with a clean GP scope.
-
Add an iteration counter Adds an integer counter GP that increments every iteration.
-
Iteration counter name Name of the counter GP (default:
gpcounter) -
Silent Mode Suppresses most log messages from this action.
-
Verbosity of messages in the log
silentnormallogs of executed pipelines(includes the child pipeline logs; useful for debugging)
¶ Description tab
See dedicated page for more information.
¶ Code tab
whileLoopPipeline is a scripted action. Embedded code is accessible and customizable through this tab.
¶ Configuration tab
See dedicated page for more information.
¶ About
Run a pipeline in a while loop.
The action repeatedly executes a child pipeline and keeps looping while a test expression evaluates to true.
whileLoopPipeline runs another pipeline (the inner pipeline) again and again. After each run, it evaluates a JavaScript-style boolean expression (the Test string). If the expression returns true, the loop continues; otherwise it stops.
By default it continues while the child’s ErrorLevel (e) is 0 (success) or 1 (warning).
¶ How the loop decides to continue
- After each run, the action evaluates Test string.
- If it’s
true→ run another iteration. - If it’s
false→ stop and return the last ErrorLevele. - If the inner pipeline crashes (e.g., throws
e ≥ 2) and your test doesn’t explicitly allow it, the loop stops and propagates that error.
Handy test examples
- Continue on success/warning (default):
((e==0) || (e==1)) - Run exactly 5 times (with counter enabled):
gpcounter < 5 - Keep going while there’s a “next page”:
(hasMore == 'yes') - Safety cap + business condition:
(hasMore == 'yes') && (gpcounter < 100)
¶ Quick start (run instructions)
¶ A) Repeat a pipeline N times
- Drop whileLoopPipeline on canvas and connect it.
- Set Pipeline to run inside loop to your child pipeline.
- Toggle Add an iteration counter = ON, leave Iteration counter name =
gpcounter. - Set Loop continues while… to
gpcounter < 3(for three iterations). - (Optional) Set Verbosity to logs of executed pipelines while testing.
- Run. You’ll see three iterations in the Process → Log.
¶ B) Poll until done using ErrorLevel
This pattern is great for batch/queue work:
-
In the child pipeline, return:
e = 1when there is more work to do,e = 0when all done.
-
In whileLoopPipeline, keep the default test
((e==0) || (e==1))or set it toe==1if you want to continue only while work remains and stop one==0. -
(Optional) Add a counter and cap it:
((e==1) && (gpcounter < 100))to prevent infinite loops.
¶ C) Passing parameters into the child
-
Click … in Optional: global Loop Params and add rows like:
bucket=my-etl-demo-bucket region=US -
In Global Parameters to pass…, list the names you want the child to receive, e.g.
bucket, region -
Decide whether to toggle Clear GPs each iteration (on = clean state; off = accumulate state across runs).
¶ Returns & side effects
-
ErrorLevel of this action = the last iteration’s
e(or the error that stopped the loop). -
Global Parameters:
- With Clear GPs ON: each iteration starts clean.
- Values listed in idGPV are forwarded to the child; after the loop, the most recent values remain in the parent scope.
-
When logs of executed pipelines is chosen, child logs appear inline under this action.
¶ Tips & best practices
- Always add a safety cap:
gpcounter < 1000avoids accidental infinite loops. - Throttle busy loops by adding a short sleep/wait inside the child pipeline when polling.
- Keep logs readable: switch Verbosity to
normalafter debugging. - Minimize state bleed by toggling Clear GPs ON unless you really need to accumulate values across iterations.
¶ Troubleshooting
- Loop never ends
Check your Test string. Add&& gpcounter < Nwhile debugging. - Child doesn’t see my parameters
Make sure their names are listed in Global Parameters to pass… and that Clear GPs isn’t wiping values you expect to persist. - No logs
Turn Silent Mode OFF and set Verbosity to logs of executed pipelines. - Stops on first warning
Use a test that explicitly allows warnings (e.g.,((e==0) || (e==1))).
