| Media-class {restfulr} | R Documentation |
Media
Description
The Media object represents a value identified by a URI. There
is a Media subclass for each media type, such as
“text/csv” or “application/xml”. Coercion methods (see
setAs) define mappings between Media subclasses
and R objects. The user does not usually need to access this
functionality directly.
Type conversion
Each Media subclass may be converted to/from one or more R
types. The mappings are established by setAs.
The following bi-directional mappings are built into the package:
application/xml, text/html |
XMLAbstractNode |
application/json | list |
text/csv | data.frame |
text/* | character
|
But call mediaCoercionTable to see what is defined in the
current session.
The as function is the canonical interface to converting
media to R objects. It (usefully) requires that the user specify the
target R type. For convenience, the mediaTarget generic
returns the default R type for a given Media object.
To support a new media type, one should define a Media subclass
with the same name as the media type (application/xml), a
corresponding mediaTarget method, and all relevant
coerce methods. See the Media class hierarchy to
determine where the new type fits.
Helpers
mediaCoercionTable(): Returns a character matrix with columns “from” and “to”, indicating the available coercions of media types to/from R objects.
Author(s)
Michael Lawrence
Examples
txt <- '{"json":{"rocks":true}}'
json <- as(txt, "application/json")
as(json, mediaTarget(json))