Media Types Reference
TMediaType (MARS.Core.MediaType) defines constants for the common MIME types used in [Produces] / [Consumes] and content negotiation. Prefer these constants over string literals.
[GET, Produces(TMediaType.APPLICATION_JSON)]
function GetData: TData;Constants
| Constant | Value |
|---|---|
TMediaType.TEXT_PLAIN | text/plain |
TMediaType.TEXT_PLAIN_UTF8 | text/plain; charset=utf-8 |
TMediaType.TEXT_XML | text/xml |
TMediaType.TEXT_HTML | text/html |
TMediaType.TEXT_YAML | text/yaml |
TMediaType.TEXT_EVENT_STREAM | text/event-stream |
TMediaType.APPLICATION_XML | application/xml |
TMediaType.APPLICATION_XML_FireDAC | application/xml-firedac |
TMediaType.APPLICATION_JSON | application/json |
TMediaType.APPLICATION_JSON_FireDAC | application/json-firedac |
TMediaType.APPLICATION_XHTML_XML | application/xhtml+xml |
TMediaType.APPLICATION_SVG_XML | application/svg+xml |
TMediaType.APPLICATION_ATOM_XML | application/atom+xml |
TMediaType.APPLICATION_OCTET_STREAM | application/octet-stream |
TMediaType.APPLICATION_FORM_URLENCODED_TYPE | application/x-www-form-urlencoded |
TMediaType.APPLICATION_YAML | application/x-yaml |
TMediaType.APPLICATION_PDF | application/pdf |
TMediaType.MULTIPART_FORM_DATA | multipart/form-data |
TMediaType.WILDCARD | */* |
Charset constants
| Constant | Value |
|---|---|
TMediaType.CHARSET_NAME | charset |
TMediaType.CHARSET_UTF8 | utf-8 |
TMediaType.CHARSET_UTF8_DEF | charset=utf-8 |
TMediaType.CHARSET_UTF16 / …_DEF | utf-16 / charset=utf-16 |
TMediaType.CHARSET_ISO_8859_1 / …_DEF | iso-8859-1 / charset=iso-8859-1 |
Use them to build a content type that declares its encoding, e.g. TMediaType.TEXT_HTML + '; ' + TMediaType.CHARSET_UTF8_DEF. This matters for textual responses: without an explicit charset, the client applies its own default (historically ISO-8859-1) and non-ASCII characters get mangled. MARS declares UTF-8 on the error responses it produces (TEXT_PLAIN_UTF8 is the default content type of EMARSHttpException) and on the textual files served by TFileSystemResource (see HTML & Templates).
Notes
*/*(WILDCARD) matches any type; writers/readers registered for it act as fallbacks (lowest affinity).- FireDAC variants (
…-firedac) carry datasets in a compact Delphi-native format; plainapplication/jsoncarries them as an interoperable array of objects. See FireDAC & Datasets. text/event-streamis used by Server-Sent Events.application/x-yamlrequiresMARS.YAML.ReadersAndWritersto be registered (used by the OpenAPI endpoint).
Parsing and matching
TMediaType.Create('application/json;charset=utf-8') parses a header value (type, subtype and parameters such as charset and quality factor q). Matches performs content-type negotiation, honoring wildcards and q priorities — this is what the content-negotiation layer uses to pick a reader/writer against the request's Accept/Content-Type.