Add custom Error type

persistence/utils.go

@@ -1,6 +1,7 @@
 package persistence
 
 import (
+	"fmt"
 	"errors"
 	"os"
 	"strings"
@@ -8,6 +9,15 @@ import (
 	"offline_twitter/scraper"
 )
 
+var NotInDatabase = errors.New("Not in database")
+
+type ErrNotInDatabase struct {
+	Table string
+	Value interface{}
+}
+func (err ErrNotInDatabase) Error() string {
+	return fmt.Sprintf("Not in database: %s %q", err.Table, err.Value)
+}
 
 // DUPE 1
 func file_exists(path string) bool {