docs(examples): provide exception handling code example

Author: jourdain

examples/exceptions/app_raw_api.py

@@ -0,0 +1,57 @@
+import logging
+import sys
+import traceback
+
+from trame.app import TrameApp
+from trame.decorators import life_cycle
+from trame.ui.html import DivLayout
+from trame.widgets import html
+
+# Disable default stdout exception
+logging.getLogger("wslink.protocol").setLevel(logging.CRITICAL)
+
+
+class MonitorException(TrameApp):
+    def __init__(self, server=None):
+        super().__init__(server)
+        self._build_ui()
+
+    def _build_ui(self):
+        with DivLayout(self.server) as self.ui:
+            html.Button("Divide by 0", click=self.divide_by_zero)
+            html.Button(
+                "No method",
+                click="trame.client.getConnection().getSession().call('no_rpc_endpoint', [], {})",
+            )
+
+    @life_cycle.server_ready
+    def _setup_wslink_listener(self, **_):
+        self.server.protocol.log_emitter.add_event_listener(
+            "exception", self.on_exception
+        )
+        self.server.protocol.log_emitter.add_event_listener("error", self.on_error)
+
+    def divide_by_zero(self):
+        return 1 / 0
+
+    def on_exception(self, exception):
+        print(">" * 60)
+        print("exception ->", exception)
+        traceback.print_exception(
+            type(exception), exception, exception.__traceback__, file=sys.stdout
+        )
+        print("<" * 60)
+
+    def on_error(self, msg):
+        print(">" * 60)
+        print("error ->", msg)
+        print("<" * 60)
+
+
+def main():
+    app = MonitorException()
+    app.server.start()
+
+
+if __name__ == "__main__":
+    main()

examples/exceptions/app_trame.py

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+import logging
+import sys
+import traceback
+
+from trame.app import TrameApp
+from trame.decorators import life_cycle
+from trame.ui.html import DivLayout
+from trame.widgets import html
+
+# Disable default stdout exception
+logging.getLogger("wslink.protocol").setLevel(logging.CRITICAL)
+
+
+class MonitorException(TrameApp):
+    def __init__(self, server=None):
+        super().__init__(server)
+        self._build_ui()
+        self.ctrl.on_exception.add(self.on_exception)
+
+    def _build_ui(self):
+        with DivLayout(self.server) as self.ui:
+            html.Button("Divide by 0", click=self.divide_by_zero)
+            html.Button("JS error", click="console.error('Yo')")
+
+    def divide_by_zero(self):
+        return 1 / 0
+
+    @life_cycle.exception
+    def on_exception(self, exception):
+        print(">" * 60)
+        print("exception ->", exception)
+        traceback.print_exception(
+            type(exception), exception, exception.__traceback__, file=sys.stdout
+        )
+        print("<" * 60)
+
+    @life_cycle.error
+    def on_js_error(self, msg):
+        if msg == "[object Object]":
+            # exception... => should fix JS to send a better msg/event
+            return
+
+        print("JS error:", msg)
+
+
+def main():
+    app = MonitorException()
+    app.server.start()
+
+
+if __name__ == "__main__":
+    main()