From 9f324ce0301ac65e85d8823102bd3680d0aba6dc Mon Sep 17 00:00:00 2001
From: Ariel Mashraki <ariel@mashraki.co.il>
Date: Wed, 11 Dec 2019 15:38:29 +0200
Subject: [PATCH] dialect/sql/sqlgraph: delete nodes in the graph

---
 dialect/sql/graph.go      | 35 ++++++++++++++++++++++++++++++++++-
 dialect/sql/graph_test.go | 17 +++++++++++++++++
 2 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/dialect/sql/graph.go b/dialect/sql/graph.go
index 7e321ff5f..a6ea35ce3 100644
--- a/dialect/sql/graph.go
+++ b/dialect/sql/graph.go
@@ -352,7 +352,7 @@ type (
 	}
 
 	// UpdateSpec holds the information for updating one
-	// or more nodes in the graph in the graph.
+	// or more nodes in the graph.
 	UpdateSpec struct {
 		Node      *NodeSpec
 		Edges     EdgeMut
@@ -393,6 +393,39 @@ func UpdateNodes(ctx context.Context, drv dialect.Driver, spec *UpdateSpec) (int
 	return affected, tx.Commit()
 }
 
+// DeleteSpec holds the information for delete one
+// or more nodes in the graph.
+type DeleteSpec struct {
+	Node      *NodeSpec
+	Predicate func(*Selector)
+}
+
+// DeleteNodes applies the DeleteSpec on the graph.
+func DeleteNodes(ctx context.Context, drv dialect.Driver, spec *DeleteSpec) (int, error) {
+	tx, err := drv.Tx(ctx)
+	if err != nil {
+		return 0, err
+	}
+	var (
+		res     Result
+		builder = Dialect(drv.Dialect())
+	)
+	selector := builder.Select().
+		From(builder.Table(spec.Node.Table))
+	if pred := spec.Predicate; pred != nil {
+		pred(selector)
+	}
+	query, args := builder.Delete(spec.Node.Table).FromSelect(selector).Query()
+	if err := tx.Exec(ctx, query, args, &res); err != nil {
+		return 0, rollback(tx, err)
+	}
+	affected, err := res.RowsAffected()
+	if err != nil {
+		return 0, rollback(tx, err)
+	}
+	return int(affected), tx.Commit()
+}
+
 type updater struct {
 	graph
 	*UpdateSpec
diff --git a/dialect/sql/graph_test.go b/dialect/sql/graph_test.go
index bd6d33b11..d6ecdb3d2 100644
--- a/dialect/sql/graph_test.go
+++ b/dialect/sql/graph_test.go
@@ -1124,6 +1124,23 @@ func TestUpdateNodes(t *testing.T) {
 	}
 }
 
+func TestDeleteNodes(t *testing.T) {
+	db, mock, err := sqlmock.New()
+	require.NoError(t, err)
+	mock.ExpectBegin()
+	mock.ExpectExec(escape("DELETE FROM `users`")).
+		WillReturnResult(sqlmock.NewResult(0, 2))
+	mock.ExpectCommit()
+	affected, err := DeleteNodes(context.Background(), OpenDB("", db), &DeleteSpec{
+		Node: &NodeSpec{
+			Table: "users",
+			ID:    &FieldSpec{Column: "id", Type: field.TypeInt},
+		},
+	})
+	require.NoError(t, err)
+	require.Equal(t, 2, affected)
+}
+
 func escape(query string) string {
 	rows := strings.Split(query, "\n")
 	for i := range rows {