source: main/waeup.sirp/trunk/src/waeup/sirp/image/README.txt @ 5979

waeup.sirp.image fields
================

The image file widget is built on top of the ImageFile object::

  >>> from waeup.sirp.image import WAeUPImageFile
  >>> file = WAeUPImageFile('foo.jpg', 'mydata')
  >>> file.filename
  'foo.jpg'
  >>> file.data
  'mydata'
  >>> file.size
  6
  >>> f = file.file
  >>> f.read()
  'mydata'

We can also create WAeUPImageFile objects from file-like objects::

  >>> from StringIO import StringIO
  >>> from zope import component
  >>> from hurry.file.interfaces import IFileRetrieval
  >>> fileretrieval = component.getUtility(IFileRetrieval)
  >>> file = fileretrieval.createFile('bar.jpg', StringIO('test data'))
  >>> file.filename
  'bar.jpg'
  >>> file.size
  9
  >>> file.data
  'test data'
  >>> f = file.file
  >>> f.read()
  'test data'

The WAeUPImageFile object normally stores the file data using ZODB
persistence. Files can however also be stored by tramline.  If
tramline is installed in Apache, the Tramline takes care of generating
ids for files and storing the file on the filesystem directly. The ids
are then passed as file data to be stored in the ZODB.

Let's first enable tramline.

The tramline directory structure is a directory with two subdirectories,
one called 'repository' and the other called 'upload'::

  >>> import tempfile, os
  >>> dirpath = tempfile.mkdtemp()
  >>> repositorypath = os.path.join(dirpath, 'repository')
  >>> uploadpath = os.path.join(dirpath, 'upload')
  >>> os.mkdir(repositorypath)
  >>> os.mkdir(uploadpath)

We create a TramlineFileRetrieval object knowing about this directory,
and register it as a utility::

  >>> from hurry.file.file import TramlineFileRetrievalBase
  >>> class TramlineFileRetrieval(TramlineFileRetrievalBase):
  ...    def getTramlinePath(self):
  ...        return dirpath
  >>> retrieval = TramlineFileRetrieval()
  >>> component.provideUtility(retrieval, IFileRetrieval)

Now let's store a file the way tramline would during upload::

  >>> f = open(os.path.join(repositorypath, '1'), 'wb')
  >>> f.write('test data')
  >>> f.close()

The file with underlying name '1' (the data stored in the ZODB will be
just '1') will now be created::

  >>> file = WAeUPImageFile('foo.jpg', '1')

The data is now '1', referring to the real file::

  >>> file.data
  '1'

Retrieving the file results in the real file::
  
  >>> f = file.file
  >>> f.read()
  'test data'

We can also retrieve its size::

  >>> file.size
  9L

Now let's disable tramline in our utility::

  >>> class TramlineFileRetrieval(TramlineFileRetrievalBase):
  ...     def getTramlinePath(self):
  ...        return dirpath
  ...     def isTramlineEnabled(self):
  ...        return False
  >>> component.provideUtility(TramlineFileRetrieval(), IFileRetrieval)

We expect the same behavior as when tramline is not installed::

  >>> file = WAeUPImageFile('foo.jpg', 'data')
  >>> f = file.file
  >>> f.read()
  'data'
  >>> file.size
  4

Clean up::

  >>> import shutil
  >>> shutil.rmtree(dirpath)