collective.updatemimetype

This Plone add-on can be used to update broken mimetypes of Blob fields.

When a file or an image is uploaded to a Blob field, its mimetype is computed based on information from the mimetypes_registry.

If that registry misses some information, the computed mimetype can be wrong or too general.

For instance, prior to version 2.0.7 of Products.MimetypeRegistry, the default mimetypes_registry of a Plone portal did not know of OpenXML mimetypes. Those files would get application/zip mimetype instead of their proper mimetypes.

As computation of mimetype happens only at load time, upgrading Products.MimetypeRegistry is not enough to fix broken mimetypes.

The function collective.updatemimetype.migrate walks over content, looks for blob fields that would get different mimetype if they would be uploaded again, and updates those field mimetypes. It can be called from a GenericSetup upgrade step with:

from collective.updatemimetype import migrate

migrate(portal)

If you want to limit migration to specific content items, you can pass a query argument to the migrate function. For instance, while the code above updates both File and Image content items of a default Plone site, the code below would only update File content items:

from collective.updatemimetype import migrate

catalog_query = {'portal_type': 'File'}

migrate(portal, catalog_query)

There is also a view registered on the portal. Call it with:

http://my_domain/my_portal/updatemimetype

The view can also be called with a query parameter. To limit update to File items, call the view with:

http://my_domain/my_portal/updatemimetype?query.portal_type:record:string=File