--- a/pkg/controllers/importqueue.go	Mon Dec 31 11:13:49 2018 +0100
+++ b/pkg/controllers/importqueue.go	Thu Jan 03 17:46:59 2019 +0100
@@ -443,12 +443,12 @@
 	err = tx.QueryRowContext(ctx, isPendingSQL, id).Scan(&pending, &kind)
 	switch {
 	case err == sql.ErrNoRows:
-		err = fmt.Errorf("Cannot find import #%d.", id)
+		err = fmt.Errorf("cannot find import #%d", id)
 		return
 	case err != nil:
 		return
 	case !pending:
-		err = fmt.Errorf("Import %d is not pending.", id)
+		err = fmt.Errorf("import %d is not pending", id)
 		return
 	}
 

--- a/pkg/controllers/json.go	Mon Dec 31 11:13:49 2018 +0100
+++ b/pkg/controllers/json.go	Thu Jan 03 17:46:59 2019 +0100
@@ -26,29 +26,55 @@
 	"gemma.intevation.de/gemma/pkg/auth"
 )
 
+// JSONResult defines the return type of JSONHandler handler function.
 type JSONResult struct {
-	Code   int
+	// Code is the HTTP status code to be set which defaults to http.StatusOK (200).
+	Code int
+	// Result is serialized to JSON.
+	// If the type is an io.Reader its copied through.
 	Result interface{}
 }
 
+// JSONDefaultLimit is default size limit in bytes of an accepted
+// input document.
 const JSONDefaultLimit = 2048
 
+// JSONHandler implements a middleware to ease the handing JSON input
+// streams and return JSON documents as output.
 type JSONHandler struct {
-	Input  func() interface{}
-	Handle func(interface{}, *http.Request, *sql.Conn) (JSONResult, error)
+	// Input (if not nil) is called to fill a data structure
+	// returned by this function.
+	Input func() interface{}
+	// Handle is called to handle the incoming HTTP request.
+	// in is the data structure returned by Input. Its nil if Input is nil.
+	// req is the incoming HTTP request.
+	// conn is the impersonated connection to the database.
+	Handle func(in interface{}, rep *http.Request, conn *sql.Conn) (JSONResult, error)
+	// NoConn if set to true no database connection is established and
+	// the conn parameter of the Handle call is nil.
 	NoConn bool
-	Limit  int64
+	// Limit overides the default size of accepted input documents.
+	// Set to a negative value to allow an arbitrary size.
+	// Handle with care!
+	Limit int64
 }
 
+// JSONError is an error if returned by the JSONHandler.Handle function
+// which ends up encoded as a JSON document.
 type JSONError struct {
-	Code    int
+	// Code is the HTTP status code of the result defaults
+	// to http.StatusInternalServerError if not set.
+	Code int
+	// The message of the error.
 	Message string
 }
 
+// Error implements the error interface.
 func (je JSONError) Error() string {
 	return fmt.Sprintf("%d: %s", je.Code, je.Message)
 }
 
+// ServeHTTP makes the JSONHandler a middleware.
 func (j *JSONHandler) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 
 	var input interface{}
@@ -147,6 +173,8 @@
 	}
 }
 
+// SendJSON sends data JSON encoded to the response writer
+// with a given HTTP status code.
 func SendJSON(rw http.ResponseWriter, code int, data interface{}) {
 	rw.Header().Set("Content-Type", "application/json")
 	rw.WriteHeader(code)

--- a/pkg/controllers/routes.go	Mon Dec 31 11:13:49 2018 +0100
+++ b/pkg/controllers/routes.go	Thu Jan 03 17:46:59 2019 +0100
@@ -26,6 +26,7 @@
 	"gemma.intevation.de/gemma/pkg/models"
 )
 
+// BindRoutes binds all the API endpoints to the exposed router.
 func BindRoutes(m *mux.Router) {
 
 	api := m.PathPrefix("/api").Subrouter()