Function Example_recursiveTraversal

examples/fs/example_test.go:19–97

()

)

func Example_recursiveTraversal() {
	client, err := ent.Open("sqlite3", "file:ent?mode=memory&cache=shared&_fk=1")
	if err != nil {
		log.Fatalf("failed opening connection to sqlite: %v", err)
	}
	defer client.Close()
	ctx := context.Background()
	// Run the auto migration tool.
	if err := client.Schema.Create(ctx); err != nil {
		log.Fatalf("failed creating schema resources: %v", err)
	}

	// Add multiple files in the following tree structure:
	//
	//	a/
	//	├─ b/
	//	│  ├─ ba
	//	│  ├─ bb
	//	│  └─ bc (deleted)
	//	├─ c/ (deleted)
	//	│  ├─ ca
	//	│  └─ cb
	//	└─ d (deleted)
	//
	a := client.File.Create().SetName("a").SaveX(ctx)
	b := client.File.Create().SetName("b").SetParent(a).SaveX(ctx)
	client.File.Create().SetName("ba").SetParent(b).SaveX(ctx)
	client.File.Create().SetName("bb").SetParent(b).SaveX(ctx)
	client.File.Create().SetName("bc").SetParent(b).SetDeleted(true).SaveX(ctx)
	c := client.File.Create().SetName("c").SetParent(a).SetDeleted(true).SaveX(ctx)
	client.File.Create().SetName("ca").SetParent(c).SaveX(ctx)
	client.File.Create().SetName("cb").SetParent(c).SaveX(ctx)
	client.File.Create().SetName("d").SetParent(a).SetDeleted(true).SaveX(ctx)

	// Query undeleted files:
	//
	//	a/
	//	└─ b/
	//	   ├─ ba
	//	   └─ bb
	//
	names := client.File.Query().
		Where(func(s *sql.Selector) {
			t1, t2 := sql.Table(file.Table), sql.Table(file.Table)
			with := sql.WithRecursive("undeleted", file.FieldID, file.FieldParentID)
			with.As(
				// The initial `SELECT` statement executed once at the start,
				// and produces the initial row or rows for the recursion.
				sql.Select(t1.Columns(file.FieldID, file.FieldParentID)...).
					From(t1).
					Where(
						sql.And(
							sql.IsNull(t1.C(file.FieldParentID)),
							sql.EQ(t1.C(file.FieldDeleted), false),
						),
					).
					// Merge the `SELECT` statement above with the following:
					UnionAll(