DB.Joins("inner join pets on pets.user_id = users.id AND pets.name = @Name", user.Pets[0]).Where("users.name = ?", user.Name).First(&users6)
	if len(users6) != 1 {
		t.Errorf("should find one users using left join with conditions, but got %v", len(users6))
	}

	dryDB := DB.Session(&gorm.Session{DryRun: true})

	if len(pets) != 1 {
		t.Fatalf("should only find one pets, but got %v", len(pets))
	}

	CheckPet(t, pets[0], *user.Pets[0])

	if count := DB.Model(&user).Where("name = ?", user.Pets[1].Name).Association("Pets").Count(); count != 1 {
		t.Fatalf("should only find one pets, but got %v", count)
	}

	if count := DB.Model(&user).Where("name = ?", "not found").Association("Pets").Count(); count != 0 {

	} else {
		sort.Slice(users2[2].Pets, func(i, j int) bool {
			return users2[2].Pets[i].ID < users2[2].Pets[j].ID
		})

		for _, pet := range users2[2].Pets[0:2] {
			if pet.Toy.Name != "" {
				t.Errorf("No toy should for user %v's pet %v but got %v", 3, pet.Name, pet.Toy.Name)
			}
		}

		CheckPet(t, *users2[2].Pets[2], *users[2].Pets[2])
	}
}

func TestPreloadEmptyData(t *testing.T) {

func TestPolymorphicHasOneAssociationForSlice(t *testing.T) {
	pets := []Pet{
		{Name: "hasone-1", Toy: Toy{Name: "toy-has-one"}},
		{Name: "hasone-2", Toy: Toy{}},
		{Name: "hasone-3", Toy: Toy{Name: "toy-has-one"}},
	}

	DB.Create(&pets)

	// Count
	AssertAssociationCount(t, pets, "Toy", 2, "")

	// Find
	var toys []Toy
	if DB.Model(&pets).Association("Toy").Find(&toys); len(toys) != 2 {

	relations := []Relation{
		{
			Name: "Account", Type: schema.HasOne, Schema: "User", FieldSchema: "Account",
			References: []Reference{{"ID", "User", "UserID", "Account", "", true}},
		},
		{
			Name: "Pets", Type: schema.HasMany, Schema: "User", FieldSchema: "Pet",
			References: []Reference{{"ID", "User", "UserID", "Pet", "", true}},
		},
		{
			Name: "Toys", Type: schema.HasMany, Schema: "User", FieldSchema: "Toy",

**FastAPI** 👷 ⏮️ 🙆 💽 & 🙆 👗 🗃 💬 💽.

⚠ ⚓ ⚙️ "🐜": "🎚-🔗 🗺" 🗃.

🐜 ✔️ 🧰 🗜 ("*🗺*") 🖖 *🎚* 📟 & 💽 🏓 ("*🔗*").

⏮️ 🐜, 👆 🛎 ✍ 🎓 👈 🎨 🏓 🗄 💽, 🔠 🔢 🎓 🎨 🏓, ⏮️ 📛 & 🆎.

🖼 🎓 `Pet` 💪 🎨 🗄 🏓 `pets`.

& 🔠 *👐* 🎚 👈 🎓 🎨 ⏭ 💽.

🖼 🎚 `orion_cat` (👐 `Pet`) 💪 ✔️ 🔢 `orion_cat.type`, 🏓 `type`. & 💲 👈 🔢 💪, ✅ `"cat"`.

👫 🐜 ✔️ 🧰 ⚒ 🔗 ⚖️ 🔗 🖖 🏓 ⚖️ 👨‍💼.

## ORMs（对象关系映射）

**FastAPI**可与任何数据库在任何样式的库中一起与 数据库进行通信。

一种常见的模式是使用“ORM”：对象关系映射。

ORM 具有在代码和数据库表（“*关系型”）中的**对象**之间转换（“*映射*”）的工具。

使用 ORM，您通常会在 SQL 数据库中创建一个代表映射的类，该类的每个属性代表一个列，具有名称和类型。

例如，一个类`Pet`可以表示一个 SQL 表`pets`。

该类的每个*实例对象都代表数据库中的一行数据。*

又例如，一个对象`orion_cat`（`Pet`的一个实例）可以有一个属性`orion_cat.type`, 对标数据库中的`type`列。并且该属性的值可以是其它，例如`"cat"`。

这些 ORM 还具有在表或实体之间建立关系的工具（比如创建多表关系）。

	}
}

func TestQueryWithAssociation(t *testing.T) {
	user := *GetUser("query_with_association", Config{Account: true, Pets: 2, Toys: 1, Company: true, Manager: true, Team: 2, Languages: 1, Friends: 3})

	if err := DB.Create(&user).Error; err != nil {
		t.Fatalf("errors happened when create user: %v", err)
	}

    return CartesianSet.create(sets);
  }

  /**
   * Returns every possible list that can be formed by choosing one element from each of the given
   * sets in order; the "n-ary <a href="http://en.wikipedia.org/wiki/Cartesian_product">Cartesian
   * product</a>" of the sets. For example:
   *
   * <pre>{@code
   * Sets.cartesianProduct(

func (s *erasureSets) StorageInfo(ctx context.Context) StorageInfo {
	var storageInfo madmin.StorageInfo

	storageInfos := make([]madmin.StorageInfo, len(s.sets))

	g := errgroup.WithNErrs(len(s.sets))
	for index := range s.sets {
		index := index
		g.Go(func() error {
			storageInfos[index] = s.sets[index].StorageInfo(ctx)
			return nil
		}, index)
	}