Overview

The Raise expression gives you a sharp tool to flag errors explicitly and stop execution of compound actions. The Try Catch expression complements it by attempting risky code and rerouting on failure.

Raise

This expression triggers an immediate exit, much like throwing an exception in code, but with a stored output for traceability. Always set an output_key to capture the error object (status, details), and add a message for clarity in logs or chats.

Try Catch

The try_catch expression allows for the execution of a compound action expression with an error handling mechanism. If the try block encounters an error, the catch block is executed, allowing for graceful error handling and recovery. This is particularly useful for managing errors in compound actions where certain actions might fail under known or unknown conditions.

Error Handling Limitations

Important: The try_catch expression does not expose the actual API error details (like error messages or response bodies) to the catch block. However, you can filter catch blocks by HTTP status codes using on_status_code, which allows you to use status codes as identifiers for different error scenarios.

For example:

• Catch 404 errors for “not found” scenarios
• Catch 500 errors for server issues
• Catch 403 errors for permission problems

This approach lets you create targeted recovery logic based on the type of failure, even without access to the detailed error information.

Supported Status Codes

Use numeric HTTP status codes in on_status_code. The field supports these error status codes:

• Client errors: 400, 401, 403, 404, 405, 408, 409, 410, 422, and 429
• Server errors: 500, 501, 502, 503, and 504

If you omit on_status_code, the catch block handles any error. The field does not match error codes in response bodies or WebSocket close codes.

Low-Code Editor

Combine the Try Catch and Raise steps for graceful error handling

1. Set Up Your Steps: Accordingly set up steps within your Try and Catch blocks

2. Filter by Status Code: For common errors and expected issues, set the catch block to trigger on specific status codes.

3. Add Graceful Exit: Add a Raise step to provide an error message and gracefully end the execution of the flow.

Syntax Reference

Raise Schema

raise:
  output_key: ERROR_VAR*  # any: Holds error details (e.g., {status: E403, message: ...})
  message: 'ERROR_MSG'    # str: Optional log/chat note

Try Catch Schema

try_catch:
  try:
    steps:  # Expressions to attempt
      - EXPRESSION_1  # e.g., flaky action
  catch:
    on_status_code: [404, 500]  # Optional
    steps:  # Recovery (no error details available)
      - EXPRESSION_2  # e.g., notify with static msg

Practical Examples

Raise

Example 1: Permission Gate

Halt non-admins

steps:
  - switch:
      cases:
        - condition: meta_info.user.role != 'admin'
          steps:
            - raise:
                output_key: auth_error
                message: "Access denied: Admin required"
  - action:
      name: perform_admin_task
      output_key: admin_task_result

Try Catch

Example 1: Action Recovery

Catch a 404, notify the admin and raise the error

try_catch:
  try:
    steps:
      - action:
          action_name: may_fail_action
          output_key: action_result
  catch:
    on_status_code: [404]
    steps:
      - action:
          action_name: notify_admin
          output_key: admin_alert
          input_args:
            message: "API returned 404—standard flake"
      - raise:
          output_key: user_error
          message: "Item not found—try a different query"

Example 2: General Fallback

Log any error and exit

try_catch:
  try:
    steps:
      - action:
          action_name: external_call
          output_key: api_data
  catch:  # Catches all
    steps:
      - raise:
          output_key: service_down
          message: "Service temporarily down—retry later"

Example 3: Status Code-Based Recovery

Handle different error types using status codes as identifiers

try_catch:
  try:
    steps:
      - action:
          action_name: api_call
          output_key: result
  catch:
    on_status_code: [403, 401]
    steps:
      - raise:
          output_key: auth_failure
          message: "Authentication failed—please check permissions"
# Separate catch for server errors
try_catch:
  try:
    steps:
      - action:
          action_name: api_call
          output_key: result
  catch:
    on_status_code: [500, 502, 503]
    steps:
      - action:
          action_name: log_server_error
          output_key: log_result
      - raise:
          output_key: server_error
          message: "Server temporarily unavailable—retry in a few minutes"