## Explanation
An example backend in Python.
```python
import os, json, time, secrets, uvicorn
from starlette.applications import Starlette
from starlette.responses import HTMLResponse, StreamingResponse
app = Starlette()
target = 'target'
def send_index():
signals = {'input': '', 'output': '', 'show': True}
index_page = f'''
Python/Starlette + Datastar Example
Python/Starlette + Datastar Example
Feed from server:
'''
return HTMLResponse(index_page)
def send_event(frag, merge=False):
yield 'event: datastar-merge-fragments\n'
if merge:
yield 'data: mergeMode upsertAttributes\n'
yield f'data: fragments {frag}\n\n'
def send_stream():
while True:
rand = secrets.token_hex(8)
frag = f'{rand}'
yield from send_event(frag)
time.sleep(1)
@app.route('/')
async def homepage(request):
return send_index()
@app.route('/get')
async def get_data(request):
signals = json.loads(dict(request.query_params)['datastar'])
signals['output'] = f"Your input: {signals['input']}, is {len(signals['input'])} long."
frag = f''
return StreamingResponse(
send_event(frag, True),
headers={"Cache-Control": "no-cache", "Connection": "keep-alive"},
media_type="text/event-stream"
)
@app.route('/target')
async def target_element(request):
today = time.strftime("%Y-%m-%d %H:%M:%S")
frag = f'{today}
'
return StreamingResponse(
send_event(frag),
headers={"Cache-Control": "no-cache", "Connection": "keep-alive"},
media_type="text/event-stream"
)
@app.route('/feed')
async def feed(request):
return StreamingResponse(
send_stream(),
headers={"Cache-Control": "no-cache", "Connection": "keep-alive"},
media_type="text/event-stream"
)
if __name__ == "__main__":
uvicorn.run(app, host="localhost", port=int(os.environ.get('PORT', 3000)))
```
```html
```