Setup views

Setup views depending on your needs:

• ObjectDownloadView when you have a model with a file field;

• StorageDownloadView when you manage files in a storage;

• PathDownloadView when you have an absolute filename on local filesystem;

• HTTPDownloadView when you have an URL (the resource is proxied);

• VirtualDownloadView when you generate a file dynamically;

• bases and mixins to make your own.