Events
/
Yield-events
A regular event handler will send a StateUpdate
when it has finished running. This works fine for basic event, but sometimes we need more complex logic. To update the UI multiple times in an event handler, we can yield
when we want to send an update.
To do so, we can use the Python keyword yield
. For every yield inside the function, a StateUpdate
will be sent to the frontend with the changes up to this point in the execution of the event handler.
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import asyncio
class MultiUpdateState(rx.State):
count: int = 0
async def timed_update(self):
for i in range(5):
await asyncio.sleep(0.5)
self.count += 1
yield
def multi_update():
return rx.vstack(
rx.text(MultiUpdateState.count),
rx.button(
"Start", on_click=MultiUpdateState.timed_update
),
)
Here is another example of yielding multiple updates with a loading icon.
import asyncio
class ProgressExampleState(rx.State):
count: int = 0
show_progress: bool = False
async def increment(self):
self.show_progress = True
yield
# Think really hard.
await asyncio.sleep(0.5)
self.count += 1
self.show_progress = False
def progress_example():
return rx.cond(
ProgressExampleState.show_progress,
rx.chakra.circular_progress(is_indeterminate=True),
rx.heading(
ProgressExampleState.count,
on_click=ProgressExampleState.increment,
_hover={"cursor": "pointer"},
),
)
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