Try / Catch

Try / Catch

Type: try-catch  ·  Package: Core Activities v1.0.0

Execute a block of activities and, if any fail, instead of stopping the entire execution, jump to an alternative block where you can react: log the error, notify, or follow a plan B. It is the key tool for your automation to be robust in the face of problems that you know may occur (a page that does not load, a file that does not exist, a system that sometimes crashes).

It has three blocks: try (what you try), catch (what to do if it fails), and finally (what always runs, no matter what).

How it works

1. Executes the activities of try.
2. If all are successful, omit the catch.
3. If anything fails, stop try at that point, save the error to errorVariable (if you defined it) —a ZoanError object with the exception details— and run the catch block.
4. In the end, it always executes finally —whether there was an error or not— ideal for freeing up resources (closing a browser, a connection).

After catch, execution continues normally with whatever comes after the Try/Catch: the error was “trapped”.

Optional parameters

Parameter	Editor	Description
errorVariable	variable name	Variable of type ZoanError holding the captured error. In the catch, access its properties: .Message (the message), .Type (the exception type, e.g. "HttpRequestException"), .Source and .StackTrace.

Subflows (lanes)

try requerido

Activities to try. If one fails, the rest of the try does not run.

catch optional

Activities that run only if something on the try failed.

finally optional

Activities that run always, whether try has failed or not.

Example

Trying to read an Excel; if it fails, log the error and continue; and close the book no matter what:

Try / Catch   errorVariable = error
 ├─ try:
 │    Excel Open        path = = asset("datos.xlsx")   output = libro
 │    Excel Read Range  excel = = libro   range = "A1:D100"   output = tabla
 ├─ catch:
 │    Log   level = error   message = = "Could not read the Excel (" + error.Type + "): " + error.Message
 │    Set Variable   name = tabla   value = = newDataTable()    // default value
 └─ finally:
      Excel Close   excel = = libro

errorVariable is a ZoanError object

The error variable is an object with the details of the captured exception:

• error.Message — the error message.
• error.Type — the exception type (e.g. "HttpRequestException", "TimeoutException"); use it to distinguish errors and branch the catch.
• error.Source and error.StackTrace — origin and stack trace, for diagnostics.

Treating it as text still works: = error or "Error: " + error use the message, so playbooks that already read it as a string won’t break.

Try/Catch vs Retry

• Use Try / Catch when you want to handle an error and continue with an alternative plan.
• Use Retry when the error is transitory (a slow website, the network) and it is enough to retry the same action.

You can combine them: a Retry inside a Try/Catch retries first and, if it still fails, the catch handles the situation.

Cancelaciones y break/continue no son errores

If you cancel the execution from the portal, or use Break/Continue inside the try, they are not treated as errors: the catch does not trigger. The finally, on the other hand, does run.

Related activities

• Retry — automatically retry a failing block.
• Throw — throw an error on purpose (which an external Try/Catch can catch).
• Log — log the captured error to catch.