README
¶
Content-Type support library for Go
This library can be used to parse the value Content-Type header (if one is present) and select an acceptable media type from the Accept header of HTTP request.
Usage
Media types are stored in MediaType structure which has Type (e.g. application), Subtype (e.g. json) and Parameters (e.g. charset: utf-8) attributes. Media types are not stored in a string because media type parameters are part of the media type (RFC 7231, 3.1.1.1. Media Type). To convert a string to MediaType use NewMediaType. To convert MediaType back to string use String function. If the Content-Type header is not present in the request, an empty MediaType is returned.
To get the MediaType corresponding to the incoming request's Content-Type header call GetMediaType and pass the http.Request pointer to it, or to parse any media type string call ParseMediaType. Either function will return error if the value is malformed according to RFC 7231, 3.1.1.5. Content-Type.
To get an acceptable media type from an Accept header of the incoming request call GetAcceptableMediaType and pass the http.Request pointer to it and an array of all the acceptable media types. The function will return the best match following the negotiation rules written in RFC 7231, 5.3.2. Accept or an error if the header is malformed or the content type in the Accept header is not supported. If the Accept header is not present in the request, the first media type from the acceptable type list is returned. If you have an Accept header value string from a source other than req.Header.Values("Accept") you can parse that in the same way using GetAcceptableMediaTypeFromHeader.
import (
"log"
"github.com/elnormous/contenttype"
)
func handleRequest(responseWriter http.ResponseWriter, request *http.Request) {
mediaType, mediaTypeError := contenttype.GetMediaType(request)
if mediaTypeError != nil {
// handle the error
}
log.Println("Media type:", mediaType.String())
availableMediaTypes := []MediaType{
contenttype.NewMediaType("application/json"),
contenttype.NewMediaType("application/xml"),
}
accepted, extParameters, acceptError := contenttype.GetAcceptableMediaType(request, availableMediaTypes)
if acceptError != nil {
// handle the error
}
log.Println("Accepted media type:", accepted.String(), "extension parameters:", extParameters)
}
Documentation
¶
Overview ¶
Package contenttype implements HTTP Content-Type and Accept header parsers.
Index ¶
- Variables
- func GetAcceptableMediaType(request *http.Request, availableMediaTypes []MediaType) (MediaType, Parameters, error)
- func GetAcceptableMediaTypeFromHeader(headerValue string, availableMediaTypes []MediaType) (MediaType, Parameters, error)
- type MediaType
- func (mediaType MediaType) Equal(mt MediaType) bool
- func (mediaType MediaType) EqualsMIME(mt MediaType) bool
- func (mediaType MediaType) IsWildcard() bool
- func (mediaType MediaType) MIME() string
- func (mediaType MediaType) Matches(mt MediaType) bool
- func (mediaType MediaType) MatchesAny(mts ...MediaType) bool
- func (mediaType *MediaType) String() string
- type Parameters
Examples ¶
Constants ¶
This section is empty.
Variables ¶
var ( // ErrInvalidMediaType is returned when the media type in the Content-Type or Accept header is syntactically invalid. ErrInvalidMediaType = errors.New("invalid media type") // ErrInvalidMediaRange is returned when the range of media types in the Content-Type or Accept header is syntactically invalid. ErrInvalidMediaRange = errors.New("invalid media range") // ErrInvalidParameter is returned when the media type parameter in the Content-Type or Accept header is syntactically invalid. ErrInvalidParameter = errors.New("invalid parameter") // ErrInvalidExtensionParameter is returned when the media type extension parameter in the Content-Type or Accept header is syntactically invalid. ErrInvalidExtensionParameter = errors.New("invalid extension parameter") // ErrNoAcceptableTypeFound is returned when Accept header contains only media types that are not in the acceptable media type list. ErrNoAcceptableTypeFound = errors.New("no acceptable type found") // ErrNoAvailableTypeGiven is returned when the acceptable media type list is empty. ErrNoAvailableTypeGiven = errors.New("no available type given") // ErrInvalidWeight is returned when the media type weight in Accept header is syntactically invalid. ErrInvalidWeight = errors.New("invalid weight") )
Functions ¶
func GetAcceptableMediaType ¶
func GetAcceptableMediaType(request *http.Request, availableMediaTypes []MediaType) (MediaType, Parameters, error)
GetAcceptableMediaType chooses a media type from available media types according to the Accept. Returns the most suitable media type or an error if no type can be selected.
func GetAcceptableMediaTypeFromHeader ¶ added in v1.0.1
func GetAcceptableMediaTypeFromHeader(headerValue string, availableMediaTypes []MediaType) (MediaType, Parameters, error)
GetAcceptableMediaTypeFromHeader chooses a media type from available media types according to the specified Accept header value. Returns the most suitable media type or an error if no type can be selected.
Types ¶
type MediaType ¶
type MediaType struct {
Type string
Subtype string
Parameters Parameters
}
MediaType holds the type, subtype and parameters of a media type.
func GetMediaType ¶
GetMediaType gets the content of Content-Type header, parses it, and returns the parsed MediaType. If the request does not contain the Content-Type header, an empty MediaType is returned.
func NewMediaType ¶
NewMediaType parses the string and returns an instance of MediaType struct.
func ParseMediaType ¶ added in v1.0.1
ParseMediaType parses the given string as a MIME media type (with optional parameters) and returns it as a MediaType. If the string cannot be parsed an appropriate error is returned.
func (MediaType) Equal ¶ added in v1.0.4
Equal checks whether the provided MIME media type matches this one including all parameters
Example ¶
ExampleMediaType_MIME comparing two media types with their parameters
package main
import (
"fmt"
"github.com/elnormous/contenttype"
)
func main() {
base := contenttype.NewMediaType("application/json; charset=utf-8")
noMatch := contenttype.NewMediaType("application/json")
match := contenttype.MediaType{Type: "application", Subtype: "json", Parameters: contenttype.Parameters{"charset": "utf-8"}}
fmt.Printf("matches exactly: %v\n", base.Equal(base))
fmt.Printf("matches exactly: %v\n", base.Equal(noMatch))
fmt.Printf("matches exactly: %v\n", base.Equal(match))
}
Output: matches exactly: true matches exactly: false matches exactly: true
func (MediaType) EqualsMIME ¶ added in v1.0.4
EqualsMIME checks whether the base MIME types match
Example ¶
ExampleMediaType_EqualsMIME comparing only on the MIME media type which must match both the type and subtype
package main
import (
"fmt"
"github.com/elnormous/contenttype"
)
func main() {
base := contenttype.NewMediaType("application/json; q=0.01; charset=utf-8")
noMatch := contenttype.NewMediaType("text/json")
partialWildcard := contenttype.NewMediaType("application/*")
diffParams := contenttype.MediaType{Type: "application", Subtype: "json", Parameters: contenttype.Parameters{"charset": "utf-8"}}
match := contenttype.MediaType{Type: "application", Subtype: "json"}
fmt.Printf("matches exactly: %v\n", base.EqualsMIME(base))
fmt.Printf("matches exactly: %v\n", base.EqualsMIME(noMatch))
fmt.Printf("matches exactly: %v\n", base.EqualsMIME(partialWildcard))
fmt.Printf("matches exactly: %v\n", base.EqualsMIME(diffParams))
fmt.Printf("matches exactly: %v\n", base.EqualsMIME(match))
}
Output: matches exactly: true matches exactly: false matches exactly: false matches exactly: true matches exactly: true
func (MediaType) IsWildcard ¶ added in v1.0.4
IsWildcard returns true if either the Type or Subtype are the wildcard character '*'
func (MediaType) MIME ¶ added in v1.0.3
MIME returns the MIME type without any of the parameters
Example ¶
ExampleMediaType_MIME comparing to MIME types
package main
import (
"fmt"
"github.com/elnormous/contenttype"
)
func main() {
mt := contenttype.NewMediaType("application/json; charset=utf-8")
fmt.Printf("MIME(): %s\n", mt.MIME())
fmt.Printf("matches: application/json: %v\n", mt.MIME() == "application/json")
fmt.Printf("matches: application/*: %v\n", mt.MIME() == "application/*")
fmt.Printf("matches: text/plain: %v\n", mt.MIME() == "text/plain")
}
Output: MIME(): application/json matches: application/json: true matches: application/*: false matches: text/plain: false
func (MediaType) Matches ¶ added in v1.0.4
Matches checks whether the MIME media types match handling wildcards in either
Example ¶
ExampleMediaType_Matches comparing only on the MIME media type which must either match exactly or be the wildcard token
package main
import (
"fmt"
"github.com/elnormous/contenttype"
)
func main() {
base := contenttype.NewMediaType("application/json; q=0.01; charset=utf-8")
noMatch := contenttype.NewMediaType("text/json")
partialWildcard := contenttype.NewMediaType("application/*")
fullWildcard := contenttype.NewMediaType("*/*")
diffParams := contenttype.MediaType{Type: "application", Subtype: "json", Parameters: contenttype.Parameters{"charset": "utf-8"}}
match := contenttype.MediaType{Type: "application", Subtype: "json"}
fmt.Printf("matches exactly: %v\n", base.Matches(base))
fmt.Printf("matches exactly: %v\n", base.Matches(noMatch))
fmt.Printf("matches exactly: %v\n", base.Matches(partialWildcard))
fmt.Printf("matches exactly: %v\n", base.Matches(fullWildcard))
fmt.Printf("matches exactly: %v\n", base.Matches(diffParams))
fmt.Printf("matches exactly: %v\n", base.Matches(match))
}
Output: matches exactly: true matches exactly: false matches exactly: true matches exactly: true matches exactly: true matches exactly: true
func (MediaType) MatchesAny ¶ added in v1.0.4
MatchesAny checks whether the MIME media types matches any of the specified list of mediatype handling wildcards in any of them
type Parameters ¶
Parameters represents media type parameters as a key-value map.
Source Files