Register all media types when in server mode

Fixes #3274

commands/server.go

@@ -24,8 +24,6 @@ import (
 	"strings"
 	"time"
 
-	"mime"
-
 	"github.com/spf13/afero"
 	"github.com/spf13/cobra"
 	"github.com/spf13/hugo/config"
@@ -95,9 +93,6 @@ func init() {
 
 	serverCmd.RunE = server
 
-	mime.AddExtensionType(".json", "application/json; charset=utf-8")
-	mime.AddExtensionType(".css", "text/css; charset=utf-8")
-
 }
 
 func server(cmd *cobra.Command, args []string) error {
@@ -168,6 +163,10 @@ func server(cmd *cobra.Command, args []string) error {
 		return err
 	}
 
+	for _, s := range Hugo.Sites {
+		s.RegisterMediaTypes()
+	}
+
 	// Watch runs its own server as part of the routine
 	if serverWatch {
 		watchDirs := c.getDirList()

hugolib/site.go

@@ -18,6 +18,7 @@ import (
 	"fmt"
 	"html/template"
 	"io"
+	"mime"
 	"net/url"
 	"os"
 	"path/filepath"
@@ -610,6 +611,15 @@ type whatChanged struct {
 	other  bool
 }
 
+// RegisterMediaTypes will register the Site's media types in the mime
+// package, so it will behave correctly with Hugo's built-in server.
+func (s *Site) RegisterMediaTypes() {
+	for _, mt := range s.mediaTypesConfig {
+		// The last one will win if there are any duplicates.
+		mime.AddExtensionType("."+mt.Suffix, mt.Type()+"; charset=utf-8")
+	}
+}
+
 // reBuild partially rebuilds a site given the filesystem events.
 // It returns whetever the content source was changed.
 func (s *Site) reProcess(events []fsnotify.Event) (whatChanged, error) {

media/mediaType.go

@@ -177,5 +177,3 @@ func DecodeTypes(maps ...map[string]interface{}) (Types, error) {
 
 	return m, nil
 }
-
-// TODO(bep) output mime.AddExtensionType