SCRIPT / API / HOOK NAME

One-sentence description of what this customization point does and when to use it.

Python version: 3.11 (embedded)
Execution context: CONTEXT (e.g. project load, simulation step, post-process)

Overview

2–3 sentences. What problem does this hook/API solve? When is the script invoked?

Scripts run inside the application process. Unhandled exceptions will DESCRIBE IMPACT.

Prerequisites

FASTSUITE E2 2026.1 or later
Script file placed in FOLDER_PATH/
OPTIONAL: Additional module or license requirement

Script Signature


# Function / class signature with type hints
def on_event_name(context: EventContext) -> None:
    """
    Called when DESCRIBE TRIGGER.
 
    Args:
        context: Provides access to DESCRIBE AVAILABLE DATA.
    """
    ...

Available API

`EventContext`

Attribute / Method	Type	Description
`context.project`	`Project`	The current project object. Read-only.
`context.item`	`Item`	The item that triggered the event.
`context.log(msg)`	`None`	Write to the application log.
`context.cancel()`	`None`	Abort the current operation.

`Project`

Attribute	Type	Description
`project.name`	`str`	Project display name.
`project.path`	`Path`	Absolute path to project file.

Examples

Minimal Example


def on_event_name(context):
    context.log(f"Triggered on: {context.item.name}")

Full Example


from __future__ import annotations
from typing import TYPE_CHECKING
 
if TYPE_CHECKING:
    from fast.api import EventContext
 
 
def on_event_name(context: EventContext) -> None:
    """Validate item before processing."""
    item = context.item
 
    if not item.name.startswith("REQ_"):
        context.log(f"WARNING: Item '{item.name}' does not follow naming convention.")
        context.cancel()
        return
 
    context.log(f"Processing: {item.name}")

Register via UI

Open Settings > Customizing > Scripts.
Click Add and browse to your .py file.
Set the Event dropdown to EVENT_NAME.
Click Save.

Execution Order

If multiple scripts are registered for the same event, they run in this order:

Built-in validation (cannot be overridden)
Project-level scripts (alphabetical)
User-level scripts (alphabetical)

Logging and Debugging


context.log("Info message")          # INFO level
context.log("Warning", level="warn") # WARN level — shown in UI
context.log("Error",   level="error")# ERROR level — shown in UI + logged to file

Log output appears in View > Application Log and in %APPDATA%/FAST/logs/.

Limitations

No access to the file system outside the project folder (sandboxed)
Maximum execution time: 30 seconds — longer scripts will be killed
Cannot import third-party packages — only the standard library and fast.*

Was this page helpful?