PIL&x2500；Python图像库─；通过CherryPy将图像缩略图上载到SQLAlchemy数据库

我正在尝试从客户端的本地文件将图像及其缩略图保存到SQLAlchemy数据库中。将HTML表单上载到CherryPy服务器。然后，使用Python图像库（PIL）处理图像以获得缩略图。最后，结果应该保存在SQLAlchemy数据库中，但失败了，可能是因为缩略图

注意：我尝试在不将缩略图临时保存在文件中的情况下执行此操作。由于数据已经在RAM中可用，我不喜欢将其保存在文件夹中，然后将其添加到数据库，最后从文件夹中删除。做这样的事是不对的

编辑4结尾的解决方案

关于ObjectImage类的表，
这是我必须使用的
这是一个要求！Python 2.7也是如此

# ! /usr/bin/env python
# -*- coding: utf-8 -*-
# image_upload.py

""" Python        2.7.3
    Cherrypy      3.2.2
    PostgreSQL    9.1
    psycopy2      2.4.5
    SQLAlchemy    0.7.10
    PIL           1.1.7
"""

以下是到PostgreSQL数据库的SQLAlchemy连接。
它作为“会话”存储在CherryPy会话中，并作为s1检索。
这样就没人会把s1当成樱桃色的东西

column       type            attributes
----------------------------------------
id           int             PRIMARY KEY
object_id    int             REFERENCES Obeject(id) ON DELETE CASCADE
filename     varchar(252)    
image        bytea           
thumbnail    bytea           
preview      boolean         

简约Python代码：

pg = sqlalchemy.create_engine(
        'postgresql://{}:{}@{}:{}/{}'.format(
            user, password, server, port, data))
Session = sessionmaker(bind=pg)
cherrypy.session['session'] = Session

  File "image_upload.py", line 1621, in store_image
    s1.commit()
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/orm/session.py", line 710, in commit
    self.transaction.commit()
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/orm/session.py", line 368, in commit
    self._prepare_impl()
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/orm/session.py", line 347, in _prepare_impl
    self.session.flush()
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/orm/session.py", line 1734, in flush
    self._flush(objects)
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/orm/session.py", line 1805, in _flush
    flush_context.execute()
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/orm/unitofwork.py", line 331, in execute
    rec.execute(self)
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/orm/unitofwork.py", line 475, in execute
    uow
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/orm/persistence.py", line 64, in save_obj
    table, insert)
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/orm/persistence.py", line 558, in _emit_insert_statements
    execute(statement, params)
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/engine/base.py", line 1449, in execute
    params)
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/engine/base.py", line 1584, in _execute_clauseelement
    compiled_sql, distilled_params
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/engine/base.py", line 1691, in _execute_context
    context)
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/engine/default.py", line 331, in do_execute
    cursor.execute(statement, parameters)
TypeError: can't escape instance to binary

CherryPy回溯：

""" 
    The variable "image_file"
    comes directly from the POSTed dictionary.
    image_file = kwargs['image_file']
"""

s1 = cherrypy.session.get('session')
image_entry = {}

img = StringIO.StringIO(image_file.file.read())
image = Image.open(img)
image_entry['image'] = image.copy()

thumb = image.copy()
thumb.thumbnail((30000, 300,), Image.ANTIALIAS)
image_entry['thumbnail'] = thumb.copy()

image_entry['object_id'] = chosen_one
image_entry['filename'] = image_file.filename
image_entry['preview'] = 't'

s1.add(ObjecteImage(**image_entry))
s1.commit()                          #line 1621

s1 = cherrypy.session.get('session')
image_entry = {}

img = StringIO.StringIO(image_file.file.read())
image = Image.open(img)
image_entry['image'] = image_file

[ ... the same as above ... ]

s1.add(ObjecteImage(**image_entry))
s1.commit()                          #line 1621

在第二次尝试中，我尝试至少直接插入最初上传的文件，以检查是否有任何更改

简约Python代码：

pg = sqlalchemy.create_engine(
        'postgresql://{}:{}@{}:{}/{}'.format(
            user, password, server, port, data))
Session = sessionmaker(bind=pg)
cherrypy.session['session'] = Session

  File "image_upload.py", line 1621, in store_image
    s1.commit()
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/orm/session.py", line 710, in commit
    self.transaction.commit()
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/orm/session.py", line 368, in commit
    self._prepare_impl()
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/orm/session.py", line 347, in _prepare_impl
    self.session.flush()
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/orm/session.py", line 1734, in flush
    self._flush(objects)
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/orm/session.py", line 1805, in _flush
    flush_context.execute()
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/orm/unitofwork.py", line 331, in execute
    rec.execute(self)
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/orm/unitofwork.py", line 475, in execute
    uow
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/orm/persistence.py", line 64, in save_obj
    table, insert)
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/orm/persistence.py", line 558, in _emit_insert_statements
    execute(statement, params)
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/engine/base.py", line 1449, in execute
    params)
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/engine/base.py", line 1584, in _execute_clauseelement
    compiled_sql, distilled_params
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/engine/base.py", line 1691, in _execute_context
    context)
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/engine/default.py", line 331, in do_execute
    cursor.execute(statement, parameters)
TypeError: can't escape instance to binary

CherryPy回溯：

""" 
    The variable "image_file"
    comes directly from the POSTed dictionary.
    image_file = kwargs['image_file']
"""

s1 = cherrypy.session.get('session')
image_entry = {}

img = StringIO.StringIO(image_file.file.read())
image = Image.open(img)
image_entry['image'] = image.copy()

thumb = image.copy()
thumb.thumbnail((30000, 300,), Image.ANTIALIAS)
image_entry['thumbnail'] = thumb.copy()

image_entry['object_id'] = chosen_one
image_entry['filename'] = image_file.filename
image_entry['preview'] = 't'

s1.add(ObjecteImage(**image_entry))
s1.commit()                          #line 1621

s1 = cherrypy.session.get('session')
image_entry = {}

img = StringIO.StringIO(image_file.file.read())
image = Image.open(img)
image_entry['image'] = image_file

[ ... the same as above ... ]

s1.add(ObjecteImage(**image_entry))
s1.commit()                          #line 1621

如何将PIL图像中的实例或PIL图像缩略图中的无转换为二进制文件？
或者是一个缓冲区，顺便说一句。。。我甚至不知道我真正需要什么。

Bytearray铸造导致：

  File "image_upload.py", line 1621, in store_image
    s1.commit()
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/orm/session.py", line 710, in commit
    self.transaction.commit()

  [ ... the same as above ... ]

  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/engine/default.py", line 331, in do_execute
    cursor.execute(statement, parameters)
TypeError: can't escape Part to binary

  File "image_upload.py", line 1611, in store_image
    image_entry['thumbnail'] = bytearray(thumb.copy())
  TypeError: iteration over non-sequence

缓冲区强制转换导致：

  File "image_upload.py", line 1621, in store_image
    s1.commit()
  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/orm/session.py", line 710, in commit
    self.transaction.commit()

  [ ... the same as above ... ]

  File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.7.10-py2.7-linux-x86_64.egg/sqlalchemy/engine/default.py", line 331, in do_execute
    cursor.execute(statement, parameters)
TypeError: can't escape Part to binary

  File "image_upload.py", line 1611, in store_image
    image_entry['thumbnail'] = bytearray(thumb.copy())
  TypeError: iteration over non-sequence

在这里没有找到答案：
-（）
-

是否有更好的工具/库用于此？
只创建缩略图的人

编辑1:

我对如何将图像对象保存到流做了一些研究。
但首先我尝试了PIL.Image.tostring（）函数：

  File "image_upload.py", line 1611, in store_image
    image_entry['thumbnail'] = buffer(thumb.copy())
  TypeError: buffer object expected

然后我尝试了BytesIO（）模块。
它导致不支持操作：fileno PIL
因为这是PIL中的一个已知错误，我用它的叉形枕头替换了PIL，并再次尝试：

thumb = image.copy()
thumb.thumbnail((30000, 300,), Image.ANTIALIAS)
thumb.tostring()
image_entry['thumbnail'] = thumb.copy()

两者都给了我SQLAlchemy类型错误：无法将实例转义为二进制
当然，就像之前错误被追溯到：

thumb = image.copy()
thumb.thumbnail((30000, 300,), Image.ANTIALIAS)
stream = BytesIO()
thumb.save(stream, "JPEG")
image_entry['thumbnail'] = stream.getvalue()

最后我用StringIO.StringIO（）替换了tesio（），但它没有改变任何事情。
我想这更像是一个特殊的炼金术问题

编辑2:

在我错误地提到未知的SQLAlchemy类型错误之前：无法将部分转义为二进制
在编辑1中更正，这是SQLAlchemy类型错误：无法将实例转义为二进制
这只是因为我试图将发布的值保存到数据库中：

s1.add(ObjectImage(**image_entry))
s1.commit()                          #line 1621

编辑3:

似乎我犯了一个错误，仍然试图插入完整大小的图像作为实例，
而缩略图已经以正确的方式“格式化”

""" 
    The variable "image_file"
    comes directly from the POSTed dictionary.
    image_file = kwargs['image_file']

    Alternative first line:
    img = StringIO.StringIO(image_file.file.read())
"""

img = BytesIO(image_file.file.read())
image = Image.open(img)
image_entry['image'] = image_file    # the dict value was meant be image.copy()

s1.add(ObjectImage(**image_entry))
s1.commit()                          #line 1621

现在表中至少插入了一个很长的十六进制代码，也许我可以使用它。
但是，图像和缩略图列似乎包含相同的十六进制代码

编辑4:

图像和缩略图不包含相同的十六进制代码，稍后确认为SQL查询。
只有前1179个字符和后4个字符是相同的，我刚在开头检查过。
两者之间的内容不同，每个条目的长度也不同。
最后，将整个代码段作为一个代码段

首先是必要的进口：

"""
    old version:
"""

img = BytesIO(image_file.file.read())
image = Image.open(img)
image_entry['image'] = image.copy()


"""
    new version:
"""

img = BytesIO(image_file.file.read())
image = Image.open(img)

fullsize = image.copy()
stream = BytesIO()
fullsize.save(stream, "JPEG")
image_entry['image'] =  stream.getvalue()


"""
    from EDIT 1:
"""

thumb = image.copy()
thumb.thumbnail((30000, 300,), Image.ANTIALIAS)
stream = BytesIO()
thumb.save(stream, "JPEG")
image_entry['thumbnail'] = stream.getvalue()

第二个引擎和会话：

from io import BytesIO
import base64
import cherrypy
import sqlalchemy
from sqlalchemy.orm import sessionmaker
from PIL import Image

第三，图像和缩略图上传代码：

pg = sqlalchemy.create_engine(
        'postgresql://{}:{}@{}:{}/{}'.format(
            user, password, server, port, data))
Session = sessionmaker(bind=pg)
cherrypy.session['session'] = Session

最后是一个简短的HTML缩略图检索代码：

s1 = cherrypy.session.get('session')
image_file = kwargs['image_file']

img = BytesIO(image_file.file.read())
image = Image.open(img)

fullsize = image.copy()
stream = BytesIO()
fullsize.save(stream, "JPEG")
image_entry['image'] =  stream.getvalue()

thumb = image.copy()
thumb.thumbnail((30000, 300,), Image.ANTIALIAS)
stream = BytesIO()
thumb.save(stream, "JPEG")
image_entry['thumbnail'] = stream.getvalue()

image_entry['sample'] = chosen_one
image_entry['filename'] = image_file.filename
image_entry['preview'] = 't'

s1.add(ObjectImage(**image_entry))
s1.commit()                          #line 1621

s1=cherrypy.session.get（'session'））
qry=（s1.query（ObjectImage.id、ObjectImage.filename、ObjectImage.缩略图）。
过滤器（ObjectImage.preview=='t'））
对于qry中的rowX：
收益率（u“”。
格式（base64.b64encode（rowX.缩略图）））

出于性能原因，我考虑编写一个额外的函数来替换数据URI方案。
但现在要感谢Neaţu Ovidiu Gabriel提到“保存到流”选项，
感谢提供这些资源的人们：

-（简单io.BytesIO（）示例）

---

-（提到不支持的操作：fileno）

我不知道Cherrypy，但我猜您正在将一个PIL.Image对象作为参数发送到s1，而s1无法执行它必须执行的操作，因为他无法识别此类对象。

没错！这就是为什么我需要一种方法将PIL.Image对象转换成更有用的东西。你不知道这方面有什么建议吗？根据，s1是到PostgreSQL数据库的SQLAlchemy连接。我会在我的帖子中编辑这个。你可以试试PIL.Image.save（…）。保存（..）的外观：保存（self，fp，format=None，**参数）。说明：将图像保存到文件或流。您应该尝试使用流-我认为如果您不想保存到磁盘，这就是您想要的。