If the body is a named list, how should it be encoded? Can be
one of form (application/x-www-form-urlencoded), multipart,
(multipart/form-data), or json (application/json).
For "multipart", list elements can be strings or objects created by
upload_file
. For "form", elements are coerced to strings
and escaped, use I()
to prevent double-escaping. For "json",
parameters are automatically "unboxed" (i.e. length 1 vectors are
converted to scalars). To preserve a length 1 vector as a vector,
wrap in I()
. For "raw", either a character or raw vector. You'll
need to make sure to set the content_type()
yourself.