entc/gen: returns affected rows in delete

Summary: Pull Request resolved: https://github.com/facebookexternal/fbc/pull/1455

Reviewed By: alexsn

Differential Revision: D17396880

fbshipit-source-id: 3a3a9849b816777bd0ef94cf55b2291705a37df6

examples/o2orecur/ent/node_delete.go

@@ -21,32 +21,41 @@ type NodeDelete struct {
 	predicates []predicate.Node
 }
 
-// Where adds a new predicate for the builder.
+// Where adds a new predicate to the delete builder.
 func (nd *NodeDelete) Where(ps ...predicate.Node) *NodeDelete {
 	nd.predicates = append(nd.predicates, ps...)
 	return nd
 }
 
-// Exec executes the deletion query.
-func (nd *NodeDelete) Exec(ctx context.Context) error {
+// Exec executes the deletion query and returns how many vertices were deleted.
+func (nd *NodeDelete) Exec(ctx context.Context) (int, error) {
 	return nd.sqlExec(ctx)
 }
 
 // ExecX is like Exec, but panics if an error occurs.
-func (nd *NodeDelete) ExecX(ctx context.Context) {
-	if err := nd.Exec(ctx); err != nil {
+func (nd *NodeDelete) ExecX(ctx context.Context) int {
+	n, err := nd.Exec(ctx)
+	if err != nil {
 		panic(err)
 	}
+	return n
 }
 
-func (nd *NodeDelete) sqlExec(ctx context.Context) error {
+func (nd *NodeDelete) sqlExec(ctx context.Context) (int, error) {
 	var res sql.Result
 	selector := sql.Select().From(sql.Table(node.Table))
 	for _, p := range nd.predicates {
 		p(selector)
 	}
 	query, args := sql.Delete(node.Table).FromSelect(selector).Query()
-	return nd.driver.Exec(ctx, query, args, &res)
+	if err := nd.driver.Exec(ctx, query, args, &res); err != nil {
+		return 0, err
+	}
+	affected, err := res.RowsAffected()
+	if err != nil {
+		return 0, err
+	}
+	return int(affected), nil
 }
 
 // NodeDeleteOne is the builder for deleting a single Node entity.
@@ -56,7 +65,15 @@ type NodeDeleteOne struct {
 
 // Exec executes the deletion query.
 func (ndo *NodeDeleteOne) Exec(ctx context.Context) error {
-	return ndo.nd.Exec(ctx)
+	n, err := ndo.nd.Exec(ctx)
+	switch {
+	case err != nil:
+		return err
+	case n == 0:
+		return &ErrNotFound{node.Label}
+	default:
+		return nil
+	}
 }
 
 // ExecX is like Exec, but panics if an error occurs.