python 3.10.11
werkzeug 2.3.7
I have a jpeg in /mnt/dragon.jpeg
I want to write unit test for a method, which has werkzeug.datastructures.FileStorage as input, and behavior is save it to a path.
I try to instantiate it with codes below:
import os
from werkzeug.datastructures import FileStorage
PATH = "/mnt/dragon.jpeg"
def get_file(filepath: str) -> FileStorage:
filename = os.path.basename(filepath)
with open(filepath, 'rb') as file:
return FileStorage(file, name=filename)
file = get_file(PATH)
The ipython instance output are:
In [8]: file
Out[8]: <FileStorage: '/mnt/dragon.jpeg' (None)>
In [9]: file.save("/mnt/saved.jpeg")
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
Cell In[9], line 1
----> 1 file.save("/mnt/saved.jpeg")
File ~/.local/lib/python3.10/site-packages/werkzeug/datastructures/file_storage.py:129, in FileStorage.save(self, dst, buffer_size)
126 close_dst = True
128 try:
--> 129 copyfileobj(self.stream, dst, buffer_size)
130 finally:
131 if close_dst:
File ~/miniconda3/lib/python3.10/shutil.py:195, in copyfileobj(fsrc, fdst, length)
193 fdst_write = fdst.write
194 while True:
--> 195 buf = fsrc_read(length)
196 if not buf:
197 break
ValueError: read of closed file
How to make the werkzeug.datastructures.FileStorage file can be saved outside the scope of open?
You can use in-memory bytes buffer(io.BytesIO). The current problem with your code is that python closes the underlying file as soon as the with block completes its execution.
import os
import io
from werkzeug.datastructures import FileStorage
PATH = "/mnt/dragon.jpeg"
def get_file(filepath: str) -> FileStorage:
filename = os.path.basename(filepath)
with open(filepath, 'rb') as file:
return FileStorage(io.BytesIO(file.read()), name=filename)
file = get_file(PATH)