# Streaming

URL: /docs/usage/streaming/
Section: usage
Tags: usage, streaming, async

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Streaming Kida can render templates as a stream of string chunks instead of building the entire output in memory. This is useful for chunked HTTP responses, Server-Sent Events, and large pages. Sync Streaming Use render_stream() for synchronous streaming: from kida import Environment env = Environment() template = env.from_string(""" <ul> {% for item in items %} <li>{{ item }}</li> {% end %} </ul> """) for chunk in template.render_stream(items=["a", "b", "c"]): send_to_client(chunk) Each statement-level boundary produces a chunk. Static content, variable output, and control flow transitions all yield independently. RenderedTemplate RenderedTemplate is a lazy iterable wrapper around render_stream(): from kida import RenderedTemplate rendered = RenderedTemplate(template, {"items": data}) # Iterate to get chunks on demand for chunk in rendered: response.write(chunk) # Or convert to string (consumes all chunks) html = str(rendered) Async Streaming Use render_stream_async() to stream templates that contain {% async for %} or {{ await }} constructs: async def stream_response(): template = env.get_template("page.html") async for chunk in template.render_stream_async(items=async_data()): yield chunk render_stream_async() also works on sync templates — it wraps the sync stream, so you can use a single code path: async for chunk in template.render_stream_async(**context): await response.write(chunk) Block Streaming Stream a single block instead of the full template: # Sync for chunk in template.render_block_stream("content", **context): send(chunk) # Async async for chunk in template.render_block_stream_async("content", **context): await send(chunk) Framework Integration Starlette / FastAPI from starlette.responses import StreamingResponse async def page(request): template = env.get_template("page.html") async def generate(): async for chunk in template.render_stream_async(items=fetch_items()): yield chunk.encode() return StreamingResponse(generate(), media_type="text/html") Flask from flask import Response @app.route("/page") def page(): template = env.get_template("page.html") return Response( template.render_stream(items=get_items()), content_type="text/html", ) What Streams All template constructs work in streaming mode: Construct Behavior Static text Yielded as-is {{ expr }} Yielded after evaluation {% for %} / {% async for %} Each iteration yields independently {% if %} / {% match %} Chosen branch yields {% extends %} / {% block %} Parent/child blocks stream {% include %} Included template streams inline {% capture %} / {% spaceless %} Buffers internally, yields processed result {% cache %} Buffers internally, yields cached result Choosing a Rendering Method Method Use Case render() Fastest — builds full string in memory render_stream() Sync streaming — chunked HTTP, large pages render_stream_async() Async streaming — async iterables, await in templates render_async() Async buffered — await support, full string output For most pages, render() is the best choice. Use streaming when the output is large or you want to start sending bytes before the template finishes rendering. See Also Async — {% async for %} and {{ await }} syntax API Reference — Full method signatures Performance — Benchmark comparisons

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