安装Django Qiniu Storage
在Django自带的后台admin中，使用的是本地文件系统来存储用户上传的数据，这样虽然也没有太大的问题。但是很多服务商本身不支持在虚拟空间里上传(SAE)。这样就需要将用户上传的图片或者其他文件保存到其他地方，这样就需要自己来实现Storage。而目前使用比较多的是各种云(bae,sae,七牛,又拍云等)，这些云存储功能大致相同，本着小猪的博客都是使用七牛的基础上想研究上传到七牛上，所以想自己写Storage来做这件事。可是在捣鼓了一个下午之后最终还是无功而返。痛定思痛之后决定还是要从基础打起，很多python的基础知识掌握的不牢还是主要原因，不过这又是一个长期的必须经过的过程。再查看了别人的源码之后发现真的是离正在的牛人还有很多的路要走，人家的思路总是这么清晰，代码总是那么整洁。
pip install django-qiniu-storage
### 配置
<table>
<thead>
<tr>
<th>Django Settings / Environment Variable</th>
<th>说明</th>
</tr>
</thead>
<tbody>
<tr>
<td>QINIU_ACCESS_KEY</td>
<td>七牛给开发者分配的 AccessKey</td>
</tr>
<tr>
<td>QINIU_SECRET_KEY</td>
<td>七牛给开发者分配的 Secret</td>
</tr>
<tr>
<td>QINIU_BUCKET_NAME</td>
<td>用来存放文件的七牛空间(bucket)的名字</td>
</tr>
<tr>
<td>QINIU_BUCKET_DOMAIN</td>
<td>七牛空间(bucket)的域名</td>
</tr>
<tr>
<td>QINIU_SECURE_URL</td>
<td>是否通过 HTTPS 来访问七牛云存储上的资源(若为'是', 可填True, true 或 1；若为'否', 可填False, false 或 0)</td>
</tr>
</tbody>
</table>
### Usage
如果你对 Django 的 Storage 系统尚不熟悉的话， Django 官方文档中的这几篇: [Managing files](https://docs.djangoproject.com/en/1.7/topics/files/), [Managing static files](https://docs.djangoproject.com/en/1.7/howto/static-files/), [The staticfiles app](https://docs.djangoproject.com/en/1.7/ref/contrib/staticfiles/) 都是很不错的阅读材料。 建议阅读完后， 再看本教程。
##### 用例1： 只用七牛托管动态生成的文件（例如用户上传的文件）
在 settings.py 里设置 `DEFAULT_FILE_STORAGE` :
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import datetime
import os
import warnings
from inspect import getargspec
from django import forms
from django.core import checks
from django.core.files.base import File
from django.core.files.images import ImageFile
from django.core.files.storage import default_storage
from django.db.models import signals
from django.db.models.fields import Field
from django.utils import six
from django.utils.deprecation import RemovedInDjango20Warning
from django.utils.encoding import force_str, force_text
from django.utils.translation import ugettext_lazy as _
class FieldFile(File):
def __init__(self, instance, field, name):
super(FieldFile, self).__init__(None, name)
self.instance = instance
self.field = field
self.storage = field.storage
self._committed = True
def __eq__(self, other):
# Older code may be expecting FileField values to be simple strings.
# By overriding the == operator, it can remain backwards compatibility.
if hasattr(other, 'name'):
return self.name == other.name
return self.name == other
def __ne__(self, other):
return not self.__eq__(other)
def __hash__(self):
return hash(self.name)
# The standard File contains most of the necessary properties, but
# FieldFiles can be instantiated without a name, so that needs to
# be checked for here.
def _require_file(self):
if not self:
raise ValueError("The '%s' attribute has no file associated with it." % self.field.name)
def _get_file(self):
self._require_file\(\)
if not hasattr(self, '_file') or self._file is None:
self._file = self.storage.open(self.name, 'rb')
return self._file
def _set_file(self, file):
self._file = file
def _del_file(self):
del self._file
file = property(_get_file, _set_file, _del_file)
def _get_path(self):
self._require_file\(\)
return self.storage.path(self.name)
path = property(_get_path)
def _get_url(self):
self._require_file\(\)
return self.storage.url(self.name)
url = property(_get_url)
def _get_size(self):
self._require_file\(\)
if not self._committed:
return self.file.size
return self.storage.size(self.name)
size = property(_get_size)
def open(self, mode='rb'):
self._require_file\(\)
self.file.open(mode)
# open\(\) doesn't alter the file's contents, but it does reset the pointer
open.alters_data = True
# In addition to the standard File API, FieldFiles have extra methods
# to further manipulate the underlying file, as well as update the
# associated model instance.
def save(self, name, content, save=True):
name = self.field.generate_filename(self.instance, name)
args, varargs, varkw, defaults = getargspec(self.storage.save)
if 'max_length' in args:
self.name = self.storage.save(name, content, max_length=self.field.max_length)
else:
warnings.warn(
'Backwards compatibility for storage backends without '
'support for the `max_length` argument in '
'Storage.save\(\) will be removed in Django 2.0.',
RemovedInDjango20Warning, stacklevel=2
)
self.name = self.storage.save(name, content)
setattr(self.instance, self.field.name, self.name)
# Update the filesize cache
self._size = content.size
self._committed = True
# Save the object because it has changed, unless save is False
if save:
self.instance.save\(\)
save.alters_data = True
def delete(self, save=True):
if not self:
return
# Only close the file if it's already open, which we know by the
# presence of self._file
if hasattr(self, '_file'):
self.close\(\)
del self.file
self.storage.delete(self.name)
self.name = None
setattr(self.instance, self.field.name, self.name)
# Delete the filesize cache
if hasattr(self, '_size'):
del self._size
self._committed = False
if save:
self.instance.save\(\)
delete.alters_data = True
def _get_closed(self):
file = getattr(self, '_file', None)
return file is None or file.closed
closed = property(_get_closed)
def close(self):
file = getattr(self, '_file', None)
if file is not None:
file.close\(\)
def __getstate__(self):
# FieldFile needs access to its associated model field and an instance
# it's attached to in order to work properly, but the only necessary
# data to be pickled is the file's name itself. Everything else will
# be restored later, by FileDescriptor below.
return {'name': self.name, 'closed': False, '_committed': True, '_file': None}
class FileDescriptor(object):
"""
The descriptor for the file attribute on the model instance. Returns a
FieldFile when accessed so you can do stuff like::
>>> from myapp.models import MyModel
>>> instance = MyModel.objects.get(pk=1)
>>> instance.file.size
Assigns a file object on assignment so you can do::
>>> with open('/tmp/hello.world', 'r') as f:
... instance.file = File(f)
"""
def __init__(self, field):
self.field = field
def __get__(self, instance=None, owner=None):
if instance is None:
raise AttributeError(
"The '%s' attribute can only be accessed from %s instances."
% (self.field.name, owner.__name__))
# This is slightly complicated, so worth an explanation.
# instance.file`needs to ultimately return some instance of `File`,
# probably a subclass. Additionally, this returned object needs to have
# the FieldFile API so that users can easily do things like
# instance.file.path and have that delegated to the file storage engine.
# Easy enough if we're strict about assignment in __set__, but if you
# peek below you can see that we're not. So depending on the current
# value of the field we have to dynamically construct some sort of
# "thing" to return.
# The instance dict contains whatever was originally assigned
# in __set__.
file = instance.__dict__[self.field.name]
# If this value is a string (instance.file = "path/to/file") or None
# then we simply wrap it with the appropriate attribute class according
# to the file field. [This is FieldFile for FileFields and
# ImageFieldFile for ImageFields; it's also conceivable that user
# subclasses might also want to subclass the attribute class]. This
# object understands how to convert a path to a file, and also how to
# handle None.
if isinstance(file, six.string_types) or file is None:
attr = self.field.attr_class(instance, self.field, file)
instance.__dict__[self.field.name] = attr
# Other types of files may be assigned as well, but they need to have
# the FieldFile interface added to them. Thus, we wrap any other type of
# File inside a FieldFile (well, the field's attr_class, which is
# usually FieldFile).
elif isinstance(file, File) and not isinstance(file, FieldFile):
file_copy = self.field.attr_class(instance, self.field, file.name)
file_copy.file = file
file_copy._committed = False
instance.__dict__[self.field.name] = file_copy
# Finally, because of the (some would say boneheaded) way pickle works,
# the underlying FieldFile might not actually itself have an associated
# file. So we need to reset the details of the FieldFile in those cases.
elif isinstance(file, FieldFile) and not hasattr(file, 'field'):
file.instance = instance
file.field = self.field
file.storage = self.field.storage
# That was fun, wasn't it?
return instance.__dict__[self.field.name]
def __set__(self, instance, value):
instance.__dict__[self.field.name] = value
class FileField(Field):
# The class to wrap instance attributes in. Accessing the file object off
# the instance will always return an instance of attr_class.
attr_class = FieldFile
# The descriptor to use for accessing the attribute off of the class.
descriptor_class = FileDescriptor
description = _("File")
def __init__(self, verbose_name=None, name=None, upload_to='', storage=None, **kwargs):
self._primary_key_set_explicitly = 'primary_key' in kwargs
self._unique_set_explicitly = 'unique' in kwargs
self.storage = storage or default_storage
self.upload_to = upload_to
if callable(upload_to):
self.generate_filename = upload_to
kwargs['max_length'] = kwargs.get('max_length', 100)
super(FileField, self).__init__(verbose_name, name, **kwargs)
def check(self, **kwargs):
errors = super(FileField, self).check(**kwargs)
errors.extend(self._check_unique\(\))
errors.extend(self._check_primary_key\(\))
return errors
def _check_unique(self):
if self._unique_set_explicitly:
return [
checks.Error(
"'unique' is not a valid argument for a %s." % self.__class__.__name__,
hint=None,
obj=self,
id='fields.E200',
)
]
else:
return []
def _check_primary_key(self):
if self._primary_key_set_explicitly:
return [
checks.Error(
"'primary_key' is not a valid argument for a %s." % self.__class__.__name__,
hint=None,
obj=self,
id='fields.E201',
)
]
else:
return []
def deconstruct(self):
name, path, args, kwargs = super(FileField, self).deconstruct\(\)
if kwargs.get("max_length", None) == 100:
del kwargs["max_length"]
kwargs['upload_to'] = self.upload_to
if self.storage is not default_storage:
kwargs['storage'] = self.storage
return name, path, args, kwargs
def get_internal_type(self):
return "FileField"
def get_prep_lookup(self, lookup_type, value):
if hasattr(value, 'name'):
value = value.name
return super(FileField, self).get_prep_lookup(lookup_type, value)
def get_prep_value(self, value):
"Returns field's value prepared for saving into a database."
value = super(FileField, self).get_prep_value(value)
# Need to convert File objects provided via a form to unicode for database insertion
if value is None:
return None
return six.text_type(value)
def pre_save(self, model_instance, add):
"Returns field's value just before saving."
file = super(FileField, self).pre_save(model_instance, add)
if file and not file._committed:
# Commit the file to storage prior to saving the model
file.save(file.name, file, save=False)
return file
def contribute_to_class(self, cls, name, **kwargs):
super(FileField, self).contribute_to_class(cls, name, **kwargs)
setattr(cls, self.name, self.descriptor_class(self))
def get_directory_name(self):
return os.path.normpath(force_text(datetime.datetime.now\(\).strftime(force_str(self.upload_to))))
def get_filename(self, filename):
return os.path.normpath(self.storage.get_valid_name(os.path.basename(filename)))
def generate_filename(self, instance, filename):
return os.path.join(self.get_directory_name\(\), self.get_filename(filename))
def save_form_data(self, instance, data):
# Important: None means "no change", other false value means "clear"
# This subtle distinction (rather than a more explicit marker) is
# needed because we need to consume values that are also sane for a
# regular (non Model-) Form to find in its cleaned_data dictionary.
if data is not None:
# This value will be converted to unicode and stored in the
# database, so leaving False as-is is not acceptable.
if not data:
data = ''
setattr(instance, self.name, data)
def formfield(self, **kwargs):
defaults = {'form_class': forms.FileField, 'max_length': self.max_length}
# If a file has been provided previously, then the form doesn't require
# that a new file is provided this time.
# The code to mark the form field as not required is used by
# form_for_instance, but can probably be removed once form_for_instance
# is gone. ModelForm uses a different method to check for an existing file.
if 'initial' in kwargs:
defaults['required'] = False
defaults.update(kwargs)
return super(FileField, self).formfield(**defaults)
class ImageFileDescriptor(FileDescriptor):
"""
Just like the FileDescriptor, but for ImageFields. The only difference is
assigning the width/height to the width_field/height_field, if appropriate.
"""
def __set__(self, instance, value):
previous_file = instance.__dict__.get(self.field.name)
super(ImageFileDescriptor, self).__set__(instance, value)
# To prevent recalculating image dimensions when we are instantiating
# an object from the database (bug #11084), only update dimensions if
# the field had a value before this assignment. Since the default
# value for FileField subclasses is an instance of field.attr_class,
# previous_file will only be None when we are called from
# Model.__init__\(\). The ImageField.update_dimension_fields method
# hooked up to the post_init signal handles the Model.__init__\(\) cases.
# Assignment happening outside of Model.__init__\(\) will trigger the
# update right here.
if previous_file is not None:
self.field.update_dimension_fields(instance, force=True)
class ImageFieldFile(ImageFile, FieldFile):
def delete(self, save=True):
# Clear the image dimensions cache
if hasattr(self, '_dimensions_cache'):
del self._dimensions_cache
super(ImageFieldFile, self).delete(save)
class ImageField(FileField):
attr_class = ImageFieldFile
descriptor_class = ImageFileDescriptor
description = _("Image")
def __init__(self, verbose_name=None, name=None, width_field=None,
height_field=None, **kwargs):
self.width_field, self.height_field = width_field, height_field
super(ImageField, self).__init__(verbose_name, name, **kwargs)
def check(self, **kwargs):
errors = super(ImageField, self).check(**kwargs)
errors.extend(self._check_image_library_installed\(\))
return errors
def _check_image_library_installed(self):
try:
from PIL import Image # NOQA
except ImportError:
return [
checks.Error(
'Cannot use ImageField because Pillow is not installed.',
hint=('Get Pillow at https://pypi.python.org/pypi/Pillow '
'or run command "pip install Pillow".'),
obj=self,
id='fields.E210',
)
]
else:
return []
def deconstruct(self):
name, path, args, kwargs = super(ImageField, self).deconstruct\(\)
if self.width_field:
kwargs['width_field'] = self.width_field
if self.height_field:
kwargs['height_field'] = self.height_field
return name, path, args, kwargs
def contribute_to_class(self, cls, name, **kwargs):
super(ImageField, self).contribute_to_class(cls, name, **kwargs)
# Attach update_dimension_fields so that dimension fields declared
# after their corresponding image field don't stay cleared by
# Model.__init__, see bug #11196.
# Only run post-initialization dimension update on non-abstract models
if not cls._meta.abstract:
signals.post_init.connect(self.update_dimension_fields, sender=cls)
def update_dimension_fields(self, instance, force=False, *args, **kwargs):
"""
Updates field's width and height fields, if defined.
This method is hooked up to model's post_init signal to update
dimensions after instantiating a model instance. However, dimensions
won't be updated if the dimensions fields are already populated. This
avoids unnecessary recalculation when loading an object from the
database.
Dimensions can be forced to update with force=True, which is how
ImageFileDescriptor.__set__ calls this method.
"""
# Nothing to update if the field doesn't have dimension fields.
has_dimension_fields = self.width_field or self.height_field
if not has_dimension_fields:
return
# getattr will call the ImageFileDescriptor's __get__ method, which
# coerces the assigned value into an instance of self.attr_class
# (ImageFieldFile in this case).
file = getattr(instance, self.attname)
# Nothing to update if we have no file and not being forced to update.
if not file and not force:
return
dimension_fields_filled = not(
(self.width_field and not getattr(instance, self.width_field))
or (self.height_field and not getattr(instance, self.height_field))
)
# When both dimension fields have values, we are most likely loading
# data from the database or updating an image field that already had
# an image stored. In the first case, we don't want to update the
# dimension fields because we are already getting their values from the
# database. In the second case, we do want to update the dimensions
# fields and will skip this return because force will be True since we
# were called from ImageFileDescriptor.__set__.
if dimension_fields_filled and not force:
return
# file should be an instance of ImageFieldFile or should be None.
if file:
width = file.width
height = file.height
else:
# No file, so clear dimensions fields.
width = None
height = None
# Update the width and height fields.
if self.width_field:
setattr(instance, self.width_field, width)
if self.height_field:
setattr(instance, self.height_field, height)
def formfield(self, **kwargs):
defaults = {'form_class': forms.ImageField}
defaults.update(kwargs)
return super(ImageField, self).formfield(**defaults)