Introduce String

pkg/types/string.go

@@ -0,0 +1,48 @@
+package types
+
+import (
+	"bytes"
+	"database/sql"
+	"database/sql/driver"
+	"encoding/json"
+)
+
+// String adds JSON support to sql.NullString.
+type String struct {
+	sql.NullString
+}
+
+// MarshalJSON implements the json.Marshaler interface.
+// Supports JSON null.
+func (s String) MarshalJSON() ([]byte, error) {
+	var v interface{}
+	if s.Valid {
+		v = s.String
+	}
+
+	return json.Marshal(v)
+}
+
+// UnmarshalJSON implements the json.Unmarshaler interface.
+// Supports JSON null.
+func (s *String) UnmarshalJSON(data []byte) error {
+	// Ignore null, like in the main JSON package.
+	if bytes.HasPrefix(data, []byte{'n'}) {
+		return nil
+	}
+
+	err := json.Unmarshal(data, &s.String)
+	if err == nil {
+		s.Valid = true
+	}
+
+	return err
+}
+
+// Assert interface compliance.
+var (
+	_ json.Marshaler   = String{}
+	_ json.Unmarshaler = (*String)(nil)
+	_ driver.Valuer    = String{}
+	_ sql.Scanner      = (*String)(nil)
+)