chickadee » atom » content-kind

Predicate and accessors for atom:content elements, which represent feed or entry content.

Atom content types may be one of "text", "html", "xhtml", or any valid MIME type; further, the structure and meaning of the content itself depends on the MIME type. To simplify this, we normalize the MIME type and we categorize it by kind:

type

The indicated MIME media type of the contents. If the type in the source document is text, html, or xhtml, we normalize this to text/plain, text/html, or application/xhtml+xml respectively. If no type is explicitly indicated, it defaults to text/plain.

kind

The computed "kind" of the contents, as a symbol. This determines how you should handle the content.

kind may be one of the following symbols, which represent

text

plain text (text/plain), the default

html

HTML text (text/html)

xhtml

an XHTML div element (application/xhtml+xml)

xml

XML; any MIME type string ending with /xml or +xml, or one of the RFC3023 XML media types

textual

text data; any other MIME type starting with text/

binary

base64-encoded binary data; any other MIME type other than those mentioned above

external

external data pointed to by a URI

To obtain the content, you should use the proper accessor based on the kind:

text

content-text, returning a string (or empty string, if no content)

html

content-text, returning an unescaped HTML string (or empty string)

xhtml

content-xhtml, returning the XHTML div element as SXML, or #f

xml

content-xml, returning the root element (whatever it is) as SXML, or #f [*]

textual

content-text, returning a string (or empty string)

binary

content-text, returning a base64-encoded string; use base64 to decode it

external

content-source, returning the external URI as a string, or #f

[*] XML contents conventionally consist of a single root element with no siblings, which is returned directly as (node ...). If more than one such element is found, they are all returned wrapped in a *TOP* node, like (*TOP* (node1 ...) (node2 ...) ...).

For xml, textual, binary and external kinds, you will then need to refer to the content media type to actually process it.

And finally the raw content accessor, just in case:

contents

Contents of the atom:contents element as a raw list of nodes. Does not try to process the content.