Merge pull request #1078 from BrianLandry/log-handler-demo

Added log handler demo

website/more_documentation/log_documentation.py

@@ -1,4 +1,5 @@
 from nicegui import ui
+from website.documentation_tools import text_demo
 
 
 def main_demo() -> None:
@@ -6,3 +7,34 @@ def main_demo() -> None:
 
     log = ui.log(max_lines=10).classes('w-full h-20')
     ui.button('Log time', on_click=lambda: log.push(datetime.now().strftime('%X.%f')[:-5]))
+
+
+def more() -> None:
+    @text_demo('Attach to a logger', '''
+        You can attach a `ui.log` element to a Python logger object so that log messages are pushed to the log element.
+    ''')
+    def logger_handler():
+        import logging
+        from datetime import datetime
+
+        logger = logging.getLogger()
+
+        class LogElementHandler(logging.Handler):
+            """A logging handler that emits messages to a log element."""
+
+            def __init__(self, element: ui.log, level: int = logging.NOTSET) -> None:
+                self.element = element
+                super().__init__(level)
+
+            def emit(self, record: logging.LogRecord) -> None:
+                try:
+                    msg = self.format(record)
+                    self.element.push(msg)
+                except (KeyboardInterrupt, SystemExit):
+                    raise
+                except:
+                    self.handleError(record)
+
+        log = ui.log(max_lines=10).classes('w-full')
+        logger.addHandler(LogElementHandler(log))
+        ui.button('Log time', on_click=lambda: logger.warning(datetime.now().strftime('%X.%f')[:-5]))