Text field with MIME type support

  Add it to your Download Basket!

 Add it to your Watch List!


Rate it!

What's new in 1.1:

  • Provide a version of the RichText field schema for use with plone.schemaeditor. Only the default_mime_type field is exposed for editing through-the-web, with a vocabulary of mimetypes derived from the AllowedContentTypes vocabulary in (which can be adjusted via Plone's markup control panel). [davisagli]
  • Log original exception when a TransformError is raised. [rochecompaan]
Read full changelog
send us
an update
GPL (GNU General Public License) 
Martin Aspeli
ROOT \ Internet \ Plone Extensions is a Plone product that provides a zope.schema style field type called RichText which can be used to store a value with a related MIME type. The value can be transformed to an output MIME type, for example to transform from structured text to HTML.

To use the field, place it in a schema like so:

from import RichText
from zope.interface import Interface

class ITest(Interface):

 bodyText = RichText(
 title=u"Body text",
 allowed_mime_types=('text/structured', 'text/plain',),
 default=u"Default value"

This specifies the default MIME type of text content as well as the default output type, and a tuple of allowed types. All these values are optional. The default MIME type is 'text/html', and the default output type is 'text/x-html-safe'. By default, allowed_mime_types is None, which means that the side-wide default set of allowable input MIME types will be permitted.

Note that the default value here is set to a unicode string, which will be considered to be of the default MIME type. This value is converted to a RichTextValue object (see below) on field initialisation, so the default property will be an object of this type.

The field actually stores an immutable object of type This object has the following attributes:

 The raw value as a unicode string.
 The MIME type of the raw text.
 A unicode string that represents the value transformed to the default output MIME type. May be None if the transformation could not be completed successfully, but will be cached after it has been successfully transformed once.
 The MIME type of the output string. This is normally copied from the field's output_mime_type property.

That the output, mimeType and outputMimeType properties will be stored in the same _p_jar as the parent content object, whilst the raw value is stored in a separate persistent object. This is to optimise for the common case where the output is frequently accessed when the object is viewed (and thus should avoid a separate persistent object load), whereas the raw value is infrequently accessed (and so should not take up memory unless specifically requested).

Transformation takes place using an ITransformer adapter. The default implementation uses Plone's portal_transforms tool to convert form one MIME type to another. Note that Products.PortalTransforms must be installed for this to work, otherwise no default ITransformer adapter is registered. You can use the [portaltransforms] extra to add Products.PortralTransforms as a dependency.

To invoke alternative transformations from a page template, you can use the following convenience syntax:

< div tal:content="structure context/@@text-transform/fieldName/text/plain" / >

Here fieldName is the name of the field (which must be found on context and contain a RichTextValue). text/plain is the desired output MIME type.

The package also contains a plone.supermodel export/import handler, which will be configured if plone.supermodel is installed. You can use the [supermodel] extra to add a plone.supermodel dependency.

A z3c.form widget will be installed if z3c.form` is installed. The [widget] extra will pull this dependency in if nothing else does.

A plone.rfc822 field marshaler will be installed if plone.rfc822 is installed. The [marshaler] extra will pull this dependency in if nothing else does.

A plone.schemaeditor field factory will be installed if plone.schemaeditor is installed. The editor extra will pull this dependency if nothing else does.

See field.txt for more details about the field's behaviour, and handler.txt for more details about the plone.supermodel handler.

Last updated on February 21st, 2012


#MIME type #text field #Plone #MIME #type #text

Add your review!