models.ServerStatus and models.LanguageTag should implement gql marshaler interface

models/lang_version.go

@@ -1,7 +1,51 @@
 package models
 
+import (
+	"fmt"
+	"io"
+	"strconv"
+	"strings"
+)
+
 type LanguageTag string
 
+const (
+	LanguageTagPL  LanguageTag = "pl"
+	LanguageTagInt LanguageTag = "en"
+	LanguageTagDE  LanguageTag = "de"
+)
+
+func (lt LanguageTag) IsValid() bool {
+	switch lt {
+	case LanguageTagPL,
+		LanguageTagInt,
+		LanguageTagDE:
+		return true
+	}
+	return false
+}
+
+func (lt LanguageTag) String() string {
+	return string(lt)
+}
+
+func (lt *LanguageTag) UnmarshalGQL(v interface{}) error {
+	str, ok := v.(string)
+	if !ok {
+		return fmt.Errorf("enums must be strings")
+	}
+
+	*lt = LanguageTag(strings.ToLower(str))
+	if !lt.IsValid() {
+		return fmt.Errorf("%s is not a valid LanguageTag", str)
+	}
+	return nil
+}
+
+func (lt LanguageTag) MarshalGQL(w io.Writer) {
+	fmt.Fprint(w, strconv.Quote(lt.String()))
+}
+
 type LangVersion struct {
 	Tag      LanguageTag `pg:",pk" json:"tag" gqlgen:"tag"`
 	Name     string      `json:"name" gqlgen:"name" pg:",unique"`

models/server.go

@@ -1,12 +1,49 @@
 package models
 
+import (
+	"fmt"
+	"io"
+	"strconv"
+	"strings"
+)
+
 type ServerStatus string
 
 const (
-	ServerStatusOpen  = "open"
-	ServerStatusClose = "close"
+	ServerStatusOpen  ServerStatus = "open"
+	ServerStatusClose ServerStatus = "close"
 )
 
+func (ss ServerStatus) IsValid() bool {
+	switch ss {
+	case ServerStatusOpen,
+		ServerStatusClose:
+		return true
+	}
+	return false
+}
+
+func (ss ServerStatus) String() string {
+	return string(ss)
+}
+
+func (ss *ServerStatus) UnmarshalGQL(v interface{}) error {
+	str, ok := v.(string)
+	if !ok {
+		return fmt.Errorf("enums must be strings")
+	}
+
+	*ss = ServerStatus(strings.ToLower(str))
+	if !ss.IsValid() {
+		return fmt.Errorf("%s is not a valid ServerStatus", str)
+	}
+	return nil
+}
+
+func (ss ServerStatus) MarshalGQL(w io.Writer) {
+	fmt.Fprint(w, strconv.Quote(ss.String()))
+}
+
 type Server struct {
 	tableName struct{} `pg:"alias:server"`