1 files changed, 40 insertions, 0 deletions
diff --git a/util/hash.go b/util/hash.go
index 088fd70e..df0a83b8 100644
--- a/util/hash.go
+++ b/util/hash.go
@@ -1,3 +1,43 @@
 package util
 
+import (
+	"fmt"
+	"io"
+)
+
 type Hash string
+
+func (h Hash) String() string {
+	return string(h)
+}
+
+func (h *Hash) UnmarshalGQL(v interface{}) error {
+	_, ok := v.(string)
+	if !ok {
+		return fmt.Errorf("labels must be strings")
+	}
+
+	*h = v.(Hash)
+
+	if !h.IsValid() {
+		return fmt.Errorf("invalid hash")
+	}
+
+	return nil
+}
+
+func (h Hash) MarshalGQL(w io.Writer) {
+	w.Write([]byte(`"` + h.String() + `"`))
+}
+
+func (h *Hash) IsValid() bool {
+	if len(*h) != 40 {
+		return false
+	}
+	for _, r := range *h {
+		if (r < 'a' || r > 'z') && (r < '0' || r > '9') {
+			return false
+		}
+	}
+	return true
+}