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Part 3 — APP Handlers [Handle Events and Errors]
In this part, we will introduce you to app handlers and tell you what they are for.
How do I make the IU buttons work?
It's very simple.
In the HTML file, I will create a button that invokes the command on click:
src/gui.html (partially)
<div>
<el-button
type="success"
@click="command('normal_handler')">
Call normal handler
</el-button>
</div>
In Python code I will handle this command using callback handler
src/main.py (partially)
@app.callback('normal_handler')
def normal_handler(api: sly.Api, task_id, context, state, app_logger):
This callback is triggered if the command name matches the name of the callback parameter.
Arguments that come to the input:
- api — api the object of the user who called the callback
- task_id — app task_id
- context — information about the environment in which the application is running
- state — state of all widgets in Python dict format
- app_logger — sly_logger with task_id
Sometimes we want the application not to crash after an error occurs.
Therefore, we can use
app.ignore_errors_and_show_dialog_window() handler:src/main.py (partially)
@app.callback('error_handler')
@app.ignore_errors_and_show_dialog_window()
def error_handler(api: sly.Api, task_id, context, state, app_logger):
logger.info('normal handler called')
raise SystemError('there could be an error message here')
App Handlers