Add login

storage/dao/database_error.go

@@ -0,0 +1,32 @@
+package dao
+
+import (
+	"fmt"
+)
+
+type Type int
+
+const (
+	ErrTypeNotFound Type = iota
+	ErrTypeDuplicate
+	ErrTypeForeignKeyViolation
+)
+
+type DAOError struct {
+	Cause error
+	Type  Type
+}
+
+func NewDAOError(t Type, cause error) error {
+	return &DAOError{
+		Type:  t,
+		Cause: cause,
+	}
+}
+
+func (e *DAOError) Error() string {
+	if e.Cause != nil {
+		return fmt.Sprintf("Type %d: %s", e.Type, e.Cause.Error())
+	}
+	return fmt.Sprintf("Type %d: no cause given", e.Type)
+}