[Flask] 대용량 데이터를 클라이언트로 전송하는 방법

출처: http://flask.pocoo.org/docs/0.12/patterns/streaming/

Basic Usage¶

This is a basic view function that generates a lot of CSV data on the fly. The trick is to have an inner function that uses a generator to generate data and to then invoke that function and pass it to a response object:

from flask import Response

@app.route('/large.csv')
def generate_large_csv():
    def generate():
        for row in iter_all_rows():
            yield ','.join(row) + '\n'
    return Response(generate(), mimetype='text/csv')

Each yield expression is directly sent to the browser. Note though that some WSGI middlewares might break streaming, so be careful there in debug environments with profilers and other things you might have enabled.

Streaming from Templates

The Jinja2 template engine also supports rendering templates piece by piece. This functionality is not directly exposed by Flask because it is quite uncommon, but you can easily do it yourself:

from flask import Response

def stream_template(template_name, **context):
    app.update_template_context(context)
    t = app.jinja_env.get_template(template_name)
    rv = t.stream(context)
    rv.enable_buffering(5)
    return rv

@app.route('/my-large-page.html')
def render_large_template():
    rows = iter_all_rows()
    return Response(stream_template('the_template.html', rows=rows))