Hen*_*Hub 1 python flask pandas
我正在查看SO 帖子，但答案不起作用。
这是我的 Flask 应用程序代码，其中 HTML 中有一个按钮可以浏览 csv 文件。最终在 pandas 中处理 CSV 文件并打印在名为的列中找到的最高值kW
from flask import Flask, make_response, request
from werkzeug.utils import secure_filename
import pandas as pd
app = Flask(__name__)
@app.route('/')
def form():
return """
<html>
<body>
<h1>Analysis</h1>
<form action="/transform" method="post" enctype="multipart/form-data">
<input type="file" name="data_file" />
<input type="submit" />
</form>
</body>
</html>
"""
@app.route('/transform', methods=["POST"])
def transform_view():
# data_file is the name of the file upload field
f = request.files['data_file']
# for security - stops a hacker e.g. trying to overwrite system files
filename = secure_filename(f.filename)
# save a copy of the uploaded file
f.save(filename)
# And then use it ...
df = pd.read_csv(filename, index_col='Date', parse_dates=True)
maxy = df.kW.max()
print(maxy)
这是简单的.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
{% for table in tables %}
{{titles[loop.index]}}
{{ table|safe }}
{% endfor %}
</body>
</html>
非常感谢任何提示...当我运行代码（flask 有效）时，在浏览过程中选择文件时会抛出错误。
TypeError: The view function did not return a valid response. The function either returned None or ended without a return statement.
完整回溯：
File "C:\Users\benb\AppData\Local\Continuum\anaconda3\lib\site-packages\flask\app.py", line 2309, in __call__
return self.wsgi_app(environ, start_response)
File "C:\Users\benb\AppData\Local\Continuum\anaconda3\lib\site-packages\flask\app.py", line 2295, in wsgi_app
response = self.handle_exception(e)
File "C:\Users\benb\AppData\Local\Continuum\anaconda3\lib\site-packages\flask\app.py", line 1741, in handle_exception
reraise(exc_type, exc_value, tb)
File "C:\Users\benb\AppData\Local\Continuum\anaconda3\lib\site-packages\flask\_compat.py", line 35, in reraise
raise value
File "C:\Users\benb\AppData\Local\Continuum\anaconda3\lib\site-packages\flask\app.py", line 2292, in wsgi_app
response = self.full_dispatch_request()
File "C:\Users\benb\AppData\Local\Continuum\anaconda3\lib\site-packages\flask\app.py", line 1816, in full_dispatch_request
return self.finalize_request(rv)
File "C:\Users\benb\AppData\Local\Continuum\anaconda3\lib\site-packages\flask\app.py", line 1831, in finalize_request
[Open an interactive python shell in this frame] response = self.make_response(rv)
File "C:\Users\benb\AppData\Local\Continuum\anaconda3\lib\site-packages\flask\app.py", line 1957, in make_response
'The view function did not return a valid response. The'
发生这种情况是因为您的路线\transform确实返回了有效的响应。该路由必须有一个 return 语句。我假设你想simple.html在调用此路由时加载，你可以执行以下操作：
render_template：from flask import render_template
return render_template('simple.html')
或者只是出于虚拟目的，您希望执行此路由而不会出现任何错误，然后您可以像下面一样返回：
return 'Transformed!'
注意：这取决于执行此路由时您实际想要返回的内容或想要呈现的内容。您可以阅读文档。
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