经过长时间的努力，我发现下面的代码是工作

@app.route("/upload", methods=['POST'])
async def omo(request):
    from sanic import response
    import os
    import aiofiles
    if not os.path.exists(appConfig["upload"]):
        os.makedirs(appConfig["upload"])
    async with aiofiles.open(appConfig["upload"]+"/"+request.files["file"][0].name, 'wb') as f:
        await f.write(request.files["file"][0].body)
    f.close()

    return response.json(True)

上面的答案很好。还有一些小的改进：
(1)因为我们使用的是Sanic，所以让我们尝试异步处理文件io：

async def write_file(path, body):
    async with aiofiles.open(path, 'wb') as f:
        await f.write(body)
    f.close()

(2)请确保该文件不会太大而导致服务器崩溃：

def valid_file_size(file_body):
    if len(file_body) < 10485760:
        return True
    return False

(3)检查文件名和文件类型，以确定文件类型是否正确：

def valid_file_type(file_name, file_type):
     file_name_type = file_name.split('.')[-1]
     if file_name_type == "pdf" and file_type == "application/pdf":
         return True
     return False

(4)确保文件名中没有危险/不安全的字符。您可以使用werkzeug.utils中的secure_filename函数：http://flask.pocoo.org/docs/0.12/patterns/fileuploads/
(5)此代码将所有功能组合在一起：

async def process_upload(request):
        # Create upload folder if doesn't exist
        if not os.path.exists(app.config.UPLOAD_DIR):
            os.makedirs(app.config.UPLOAD_DIR)

        # Ensure a file was sent
        upload_file = request.files.get('file_names')
        if not upload_file:
            return redirect("/?error=no_file")

        # Clean up the filename in case it creates security risks
        filename = secure_filename(upload_file.name)

        # Ensure the file is a valid type and size, and if so
        # write the file to disk and redirect back to main
        if not valid_file_type(upload_file.name, upload_file.type):
            return redirect('/?error=invalid_file_type')
        elif not valid_file_size(upload_file.body):
            return redirect('/?error=invalid_file_size')
        else:
            file_path = f"{app.config.UPLOAD_DIR}/{str(datetime.now())}.pdf"
            await write_file(file_path, upload_file.body)
            return redirect('/?error=none')

我写了一篇博文，介绍了我如何在Sanic中处理文件上传。我添加了一些文件验证和异步文件写入。我希望其他人会觉得这很有帮助：
https://blog.fcast.co/2019/06/16/file-upload-handling-using-asynchronous-file-writing/

下面是一个特定文件类型的文件上传示例（这个是pdf文件）

from sanic import Sanic
from sanic.response import json
from pathlib import os
from datetime import datetime

app = Sanic()

config = {}
config["upload"] = "./tests/uploads"


@app.route("/upload", methods=['POST'])
def post_json(request):
    if not os.path.exists(config["upload"]):
        os.makedirs(config["upload"])
    test_file = request.files.get('file')
    file_parameters = {
        'body': test_file.body,
        'name': test_file.name,
        'type': test_file.type,
    }
    if file_parameters['name'].split('.')[-1] == 'pdf':
        file_path = f"{config['upload']}/{str(datetime.now())}.pdf"
        with open(file_path, 'wb') as f:
            f.write(file_parameters['body'])
        f.close()
        print('file wrote to disk')

        return json({ "received": True, "file_names": request.files.keys(), "success": True })
    else:
        return json({ "received": False, "file_names": request.files.keys(), "success": False, "status": "invalid file uploaded" })

有关其他请求类型的示例，请参阅官方文档（https://sanic.readthedocs.io/en/latest/sanic/request_data.html）

上面的答案忽略了html文件的必要存在。也有一些bug在那里。现在我发布我的答案，在我的机器上工作。
代码结合了sanic和html。

import asyncio

from sanic import Sanic
from sanic.response import html, file, text
from sanic.request import Request

import os
app = Sanic('something')

@app.route("/")
async def index(request: Request):
    return html("""
        <form action="/upload" method="post" enctype="multipart/form-data">
            <input type="file" name="file">
            <input type="submit" value="Upload">
        </form>
    """)

@app.route("/upload", methods=["POST"])
async def upload(request: Request):
    file_ = request.files.get("file")
    return await file((os.getcwd() + '/tempdir/some_file_feedback.csv'),  filename="your_match.pdf")

if __name__ == "__main__":
    app.run(host="0.0.0.0", port=6000)

以上不仅接收上传的文件，而且在另一个文件中返回响应。希望这对很多人有帮助。