1 files changed, 19 insertions, 0 deletions
diff --git a/oblast.go b/oblast.go
index 52c0cfd..42305e6 100644
--- a/oblast.go
+++ b/oblast.go
@@ -100,6 +100,7 @@ import (
 	"database/sql/driver"
 	"fmt"
 	"reflect"
+	"strings"
 )
 
 var (
@@ -170,3 +171,21 @@ func MustNewStore[R any](dialect Dialect, opts ...PlanOption) Store[R] {
 	}
 	return store
 }
+
+// MissingRecordError is returned by [Store.Update] if one of the rows to be updated does not exist in the DB.
+type MissingRecordError[R any] struct {
+	// The record that was provided to [Store.Update],
+	// but for which no row with the same primary key values could be located.
+	Record R
+	plan   plan
+}
+
+// Error implements the builtin/error interface.
+func (e MissingRecordError[R]) Error() string {
+	keyDescs := make([]string, len(e.plan.PrimaryKeyColumnNames))
+	v := reflect.ValueOf(e.Record)
+	for idx, columnName := range e.plan.PrimaryKeyColumnNames {
+		keyDescs[idx] = fmt.Sprintf("%s = %#v", columnName, v.FieldByIndex(e.plan.IndexByColumnName[columnName]))
+	}
+	return fmt.Sprintf("could not UPDATE record that does not exist in the database: %s", strings.Join(keyDescs, ", "))
+}