保存上传的base64数据会导致TypeError：需要类似字节的对象，而不是“str” [英] Saving uploaded base64 data gives TypeError: a bytes-like object is required, not 'str'

问题描述

我正在使用JavaScript库上传图片。它将图像数据放置在一个表单字段中，该表单字段是一个带有文件名和base64编码数据的JSON编码对象。

当我试图将图像保存在Flask中时，I得到这个错误：
$ b $ pre $ builtins.TypeError TypeError：需要类似字节的对象，而不是'str'


使用正确的名称创建映像文件，但数据已损坏，无法打开。如何保存上传的数据？

$ b

  app =烧瓶（__ name__）
 UPLOAD_FOLDER = app.root_path +'/ images /'
 
 @ app.route（'/'，methods = ['GET'，'POST']）
 def index（）：
 if request.method =='POST'：
 image_base = json.loads（request.form ['file']）['output'] ['image'] 
 image_base = image_base [ image_base.find（'，'）+ 1：] 
 file_data = io.StringIO（image_base）
 file = FileStorage（file_data，filename = json.loads（from_form）['output'] ['name '））
 filename = secure_filename（file.filename）
 file.save（os.path.join（app.config ['UPLOAD_FOLDER']，filename））
 return redirect（url_for 'uploaded_file'，filename = filename））
 
 return render_template（'index.html'，methods = ['GET'，'POST']）
  

 文件/usr/local/lib/python3.5/site-packages /flask/app.py行1836，在__call__ 
返回self.wsgi_app（environ，start_response）
文件/usr/local/lib/python3.5/site-packages/flask/app.py，行1820，在wsgi_app 
 response = self.make_response（self.handle_exception（e））
在handle_exception中的文件/usr/local/lib/python3.5/site-packages/flask/app.py，第1403行
 reraise（exc_type，exc_value，tb）
文件/usr/local/lib/python3.5/site-packages/flask/_compat.py，第33行，重新加注
 raise值
在wsgi_app 
响应= self.full_dispatch_request（）
文件/usr/local/lib/python3.5/site-packages/flask/app.py，行1817 /usr/local/lib/python3.5/site-packages/flask/app.py，第1477行，在full_dispatch_request 
 rv = self.handle_user_exception（e）
文件/ usr / local /lib/python3.5/site-packages/flask/app.py，第1381行，在handle_user_exception 
 reraise（exc_type，exc_value，tb）
文件/ usr / local / lib / python3。 5 / site-packages / flask / _compat.py，第33行e 
提高价值
文件/usr/local/lib/python3.5/site-packages/flask/app.py，第1475行，在full_dispatch_request 
 rv = self.dispatch_request（ ）
文件/usr/local/lib/python3.5/site-packages/flask/app.py，第1461行，在dispatch_request 
返回self.view_functions [rule.endpoint]（** req.view_args）
文件/Users/kr/PycharmProjects/instaup/instaup.py，第32行，在索引
 file.save（os.path.join（app.config ['UPLOAD_FOLDER' ]，文件名））
文件/usr/local/lib/python3.5/site-packages/werkzeug/datastructures.py，行2656，保存
 copyfileobj（self.stream，dst， buffer_size）
文件/usr/local/Cellar/python3/3.5.1/Frameworks/Python.framework/Versions/3.5/lib/python3.5/shutil.py，第76行，位于copyfileobj 
 fdst.write（buf）
 TypeError：需要类似字节的对象，而不是'str'
  

解决方案 代表一个字符串，而不是字节，你想 BytesIO 。 Base64编码的数据不是实际的图像字节，需要使用进行解码 b64decode 。

  file_data = io.BytesIO（b64decode （image_base））
  

I am using a JavaScript library to upload an image. It places the image data in a form field that is a JSON encoded object with the file name and base64 encoded data.

When I try to save the image in Flask, I get this error:

builtins.TypeError TypeError: a bytes-like object is required, not 'str'

The image file is created with the correct name, but the data is corrupt, I can't open it. How do I save the uploaded data?

app = Flask(__name__)
UPLOAD_FOLDER = app.root_path + '/images/'

@app.route('/', methods=['GET', 'POST'])
def index():
    if request.method == 'POST':
        image_base = json.loads(request.form['file'])['output']['image']
        image_base = image_base[image_base.find(',')+1:]
        file_data = io.StringIO(image_base)
        file = FileStorage(file_data, filename=json.loads(from_form)['output']['name'])
        filename = secure_filename(file.filename)
        file.save(os.path.join(app.config['UPLOAD_FOLDER'], filename))
        return redirect(url_for('uploaded_file', filename=filename))

    return render_template('index.html', methods=['GET', 'POST'])

  File "/usr/local/lib/python3.5/site-packages/flask/app.py", line 1836, in __call__
    return self.wsgi_app(environ, start_response)
  File "/usr/local/lib/python3.5/site-packages/flask/app.py", line 1820, in wsgi_app
    response = self.make_response(self.handle_exception(e))
  File "/usr/local/lib/python3.5/site-packages/flask/app.py", line 1403, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/usr/local/lib/python3.5/site-packages/flask/_compat.py", line 33, in reraise
    raise value
  File "/usr/local/lib/python3.5/site-packages/flask/app.py", line 1817, in wsgi_app
    response = self.full_dispatch_request()
  File "/usr/local/lib/python3.5/site-packages/flask/app.py", line 1477, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/usr/local/lib/python3.5/site-packages/flask/app.py", line 1381, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/usr/local/lib/python3.5/site-packages/flask/_compat.py", line 33, in reraise
    raise value
  File "/usr/local/lib/python3.5/site-packages/flask/app.py", line 1475, in full_dispatch_request
    rv = self.dispatch_request()
  File "/usr/local/lib/python3.5/site-packages/flask/app.py", line 1461, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/Users/kr/PycharmProjects/instaup/instaup.py", line 32, in index
    file.save(os.path.join(app.config['UPLOAD_FOLDER'], filename))
  File "/usr/local/lib/python3.5/site-packages/werkzeug/datastructures.py", line 2656, in save
    copyfileobj(self.stream, dst, buffer_size)
  File "/usr/local/Cellar/python3/3.5.1/Frameworks/Python.framework/Versions/3.5/lib/python3.5/shutil.py", line 76, in copyfileobj
    fdst.write(buf)
TypeError: a bytes-like object is required, not 'str'

解决方案

StringIO represents a string, not bytes, you want BytesIO. Base64 encoded data is not the actual image bytes, it needs to be decoded with b64decode.

file_data = io.BytesIO(b64decode(image_base))

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