===========
File Widget
===========
The file widget allows you to upload a new file to the server. The "file" type
of the "INPUT" element is described here:
http://www.w3.org/TR/1999/REC-html401-19991224/interact/forms.html#edef-INPUT
As for all widgets, the file widget must provide the new ``IWidget``
interface:
>>> from zope.interface.verify import verifyClass
>>> from z3c.form import interfaces
>>> from z3c.form.browser import file
>>> verifyClass(interfaces.IWidget, file.FileWidget)
True
The widget can be instantiated only using the request:
>>> from z3c.form.testing import TestRequest
>>> request = TestRequest()
>>> widget = file.FileWidget(request)
Before rendering the widget, one has to set the name and id of the widget:
>>> widget.id = 'widget.id'
>>> widget.name = 'widget.name'
We also need to register the template for the widget:
>>> import zope.component
>>> from zope.pagetemplate.interfaces import IPageTemplate
>>> from z3c.form.testing import getPath
>>> from z3c.form.widget import WidgetTemplateFactory
>>> zope.component.provideAdapter(
... WidgetTemplateFactory(getPath('file_input.pt'), 'text/html'),
... (None, None, None, None, interfaces.IFileWidget),
... IPageTemplate, name=interfaces.INPUT_MODE)
If we render the widget we get a simple input element:
>>> print(widget.render())
Let's now make sure that we can extract user entered data from a widget:
>>> try:
... from StringIO import StringIO as BytesIO
... except ImportError:
... from io import BytesIO
>>> myfile = BytesIO(b'My file contents.')
>>> widget.request = TestRequest(form={'widget.name': myfile})
>>> widget.update()
>>> isinstance(widget.extract(), BytesIO)
True
If nothing is found in the request, the default is returned:
>>> widget.request = TestRequest()
>>> widget.update()
>>> widget.extract()
Make also sure that we can handle FileUpload objects given form a file upload.
>>> from zope.publisher.browser import FileUpload
Let's define a FieldStorage stub:
>>> class FieldStorageStub:
... def __init__(self, file):
... self.file = file
... self.headers = {}
... self.filename = 'foo.bar'
Now build a FileUpload:
>>> myfile = BytesIO(b'File upload contents.')
>>> aFieldStorage = FieldStorageStub(myfile)
>>> myUpload = FileUpload(aFieldStorage)
>>> widget.request = TestRequest(form={'widget.name': myUpload})
>>> widget.update()
>>> widget.extract()
If we render them, we get a regular file upload widget:
>>> print(widget.render())