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// Copyright 2019-present Facebook Inc. All rights reserved.
// This source code is licensed under the Apache 2.0 license found
// in the LICENSE file in the root directory of this source tree.
package main
import (
"context"
"fmt"
"log"
"github.com/facebook/ent/examples/o2mrecur/ent"
"github.com/facebook/ent/examples/o2mrecur/ent/node"
_ "github.com/mattn/go-sqlite3"
)
func Example_O2MRecur() {
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)
}
if err := Do(ctx, client); err != nil {
log.Fatal(err)
}
// Output:
// Tree leafs [1 3 5]
// [1 3 5]
// Node(id=1, value=2)
}
func Do(ctx context.Context, client *ent.Client) error {
root, err := client.Node.
Create().
SetValue(2).
Save(ctx)
if err != nil {
return fmt.Errorf("creating the root: %v", err)
}
// Add additional nodes to the tree:
//
// 2
// / \
// 1 4
// / \
// 3 5
//
// Unlike `Save`, `SaveX` panics if an error occurs.
n1 := client.Node.
Create().
SetValue(1).
SetParent(root).
SaveX(ctx)
n4 := client.Node.
Create().
SetValue(4).
SetParent(root).
SaveX(ctx)
n3 := client.Node.
Create().
SetValue(3).
SetParent(n4).
SaveX(ctx)
n5 := client.Node.
Create().
SetValue(5).
SetParent(n4).
SaveX(ctx)
fmt.Println("Tree leafs", []int{n1.Value, n3.Value, n5.Value})
// Output: Tree leafs [1 3 5]
// Get all leafs (nodes without children).
// Unlike `Int`, `IntX` panics if an error occurs.
ints := client.Node.
Query(). // All nodes.
Where(node.Not(node.HasChildren())). // Only leafs.
Order(ent.Asc(node.FieldValue)). // Order by their `value` field.
GroupBy(node.FieldValue). // Extract only the `value` field.
IntsX(ctx)
fmt.Println(ints)
// Output: [1 3 5]
// Get orphan nodes (nodes without parent).
// Unlike `Only`, `OnlyX` panics if an error occurs.
orphan := client.Node.
Query().
Where(node.Not(node.HasParent())).
OnlyX(ctx)
fmt.Println(orphan)
// Output: Node(id=1, value=2)
return nil
}
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