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242
examples/traversal/example_test.go
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242
examples/traversal/example_test.go
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// Copyright 2019-present Facebook Inc. All rights reserved.
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// This source code is licensed under the Apache 2.0 license found
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// in the LICENSE file in the root directory of this source tree.
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package main
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import (
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"context"
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"fmt"
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"log"
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"entgo.io/ent/examples/traversal/ent"
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"entgo.io/ent/examples/traversal/ent/group"
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"entgo.io/ent/examples/traversal/ent/pet"
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"entgo.io/ent/examples/traversal/ent/user"
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_ "github.com/mattn/go-sqlite3"
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)
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func Example_traversal() {
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client, err := ent.Open("sqlite3", "file:ent?mode=memory&cache=shared&_fk=1")
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if err != nil {
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log.Fatalf("failed opening connection to sqlite: %v", err)
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}
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defer client.Close()
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ctx := context.Background()
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// Run the auto migration tool.
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if err := client.Schema.Create(ctx); err != nil {
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log.Fatalf("failed creating schema resources: %v", err)
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}
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if err := Gen(ctx, client); err != nil {
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log.Fatal(err)
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}
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if err := Traverse(ctx, client); err != nil {
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log.Fatal(err)
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}
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if err := Traverse2(ctx, client); err != nil {
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log.Fatal(err)
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}
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// Generate a group of entities in a transaction.
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if err := GenTx(ctx, client); err != nil {
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log.Fatal(err)
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}
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// Wrap an existing function ("Gen") in a transaction.
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if err := WrapGen(ctx, client); err != nil {
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log.Fatal(err)
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}
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// WithTx helper.
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if err := WithTx(ctx, client, func(tx *ent.Tx) error {
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return Gen(ctx, tx.Client())
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}); err != nil {
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log.Fatal(err)
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}
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// Output:
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// Pets created: Pet(id=1, name=Pedro) Pet(id=2, name=Xabi) Pet(id=3, name=Coco)
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// User(id=3, age=37, name=Alex)
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// [Pet(id=1, name=Pedro) Pet(id=2, name=Xabi)]
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// User(id=5, age=30, name=Ariel)
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// Pets created: Pet(id=4, name=Pedro) Pet(id=5, name=Xabi) Pet(id=6, name=Coco)
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// Pets created: Pet(id=7, name=Pedro) Pet(id=8, name=Xabi) Pet(id=9, name=Coco)
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}
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func Gen(ctx context.Context, client *ent.Client) error {
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hub, err := client.Group.
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Create().
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SetName("Github").
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Save(ctx)
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if err != nil {
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return fmt.Errorf("failed creating the group: %w", err)
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}
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// Create the admin of the group.
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// Unlike `Save`, `SaveX` panics if an error occurs.
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dan := client.User.
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Create().
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SetAge(29).
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SetName("Dan").
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AddManage(hub).
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SaveX(ctx)
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// Create "Ariel" and its pets.
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a8m := client.User.
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Create().
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SetAge(30).
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SetName("Ariel").
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AddGroups(hub).
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AddFriends(dan).
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SaveX(ctx)
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pedro := client.Pet.
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Create().
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SetName("Pedro").
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SetOwner(a8m).
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SaveX(ctx)
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xabi := client.Pet.
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Create().
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SetName("Xabi").
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SetOwner(a8m).
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SaveX(ctx)
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// Create "Alex" and its pets.
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alex := client.User.
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Create().
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SetAge(37).
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SetName("Alex").
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SaveX(ctx)
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coco := client.Pet.
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Create().
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SetName("Coco").
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SetOwner(alex).
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AddFriends(pedro).
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SaveX(ctx)
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fmt.Println("Pets created:", pedro, xabi, coco)
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// Output:
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// Pets created: Pet(id=1, name=Pedro) Pet(id=2, name=Xabi) Pet(id=3, name=Coco)
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return nil
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}
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func Traverse(ctx context.Context, client *ent.Client) error {
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owner, err := client.Group. // GroupClient.
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Query(). // Query builder.
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Where(group.Name("Github")). // Filter only GitHub group (only 1).
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QueryAdmin(). // Getting Dan.
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QueryFriends(). // Getting Dan's friends: [Ariel].
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QueryPets(). // Their pets: [Pedro, Xabi].
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QueryFriends(). // Pedro's friends: [Coco], Xabi's friends: [].
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QueryOwner(). // Coco's owner: Alex.
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Only(ctx) // Expect only one entity to return in the query.
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if err != nil {
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return fmt.Errorf("failed querying the owner: %w", err)
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}
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fmt.Println(owner)
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// Output:
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// User(id=3, age=37, name=Alex)
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return nil
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}
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// Traverse2 example from the doc.
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func Traverse2(ctx context.Context, client *ent.Client) error {
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pets, err := client.Pet.
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Query().
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Where(
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pet.HasOwnerWith(
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user.HasFriendsWith(
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user.HasManage(),
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),
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),
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).
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All(ctx)
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if err != nil {
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return fmt.Errorf("failed querying the pets: %w", err)
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}
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fmt.Println(pets)
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// Output:
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// [Pet(id=1, name=Pedro) Pet(id=2, name=Xabi)]
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return nil
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}
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// GenTx example from the doc.
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func GenTx(ctx context.Context, client *ent.Client) error {
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tx, err := client.Tx(ctx)
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if err != nil {
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return fmt.Errorf("starting a transaction: %w", err)
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}
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hub, err := tx.Group.
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Create().
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SetName("Github").
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Save(ctx)
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if err != nil {
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return rollback(tx, fmt.Errorf("failed creating the group: %w", err))
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}
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// Create the admin of the group.
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dan, err := tx.User.
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Create().
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SetAge(29).
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SetName("Dan").
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AddManage(hub).
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Save(ctx)
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if err != nil {
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return rollback(tx, err)
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}
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// Create user "Ariel".
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a8m, err := tx.User.
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Create().
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SetAge(30).
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SetName("Ariel").
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AddGroups(hub).
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AddFriends(dan).
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Save(ctx)
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if err != nil {
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return rollback(tx, err)
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}
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fmt.Println(a8m)
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// Output:
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// User(id=1, age=30, name=Ariel)
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return tx.Commit()
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}
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// WrapGen wraps the existing "Gen" function in a transaction.
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func WrapGen(ctx context.Context, client *ent.Client) error {
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tx, err := client.Tx(ctx)
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if err != nil {
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return err
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}
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txClient := tx.Client()
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// Use the same "Gen" as above, but give it the transactional client; no code changes to "Gen".
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if err := Gen(ctx, txClient); err != nil {
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return rollback(tx, err)
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}
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return tx.Commit()
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}
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// WithTx example from the doc.
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func WithTx(ctx context.Context, client *ent.Client, fn func(tx *ent.Tx) error) error {
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tx, err := client.Tx(ctx)
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if err != nil {
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return err
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}
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defer func() {
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if v := recover(); v != nil {
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tx.Rollback()
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panic(v)
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}
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}()
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if err := fn(tx); err != nil {
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if rerr := tx.Rollback(); rerr != nil {
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err = fmt.Errorf("%w: rolling back transaction: %v", err, rerr)
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}
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return err
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}
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if err := tx.Commit(); err != nil {
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return fmt.Errorf("committing transaction: %w", err)
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}
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return nil
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}
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// rollback calls to tx.Rollback and wraps the given error with the rollback error if occurred.
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func rollback(tx *ent.Tx, err error) error {
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if rerr := tx.Rollback(); rerr != nil {
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err = fmt.Errorf("%w: %v", err, rerr)
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}
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return err
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}
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