查询文档 #

一、Get查询 #

1.1 基本Get #

javascript

// 通过Ref获取文档
Get(Ref(Collection("users"), "123456"))

// 通过索引获取文档
Get(Match(Index("users_by_email"), "tom@example.com"))

1.2 Get返回值 #

javascript

// Get返回完整文档
{
  ref: Ref(Collection("users"), "123456"),
  ts: 1704067200000000,
  data: {
    name: "Tom",
    email: "tom@example.com",
    age: 30
  }
}

1.3 历史查询 #

javascript

// 获取特定时间点的文档
Get(
  Ref(Collection("users"), "123456"),
  Time("2024-01-01T00:00:00Z")
)

// 获取昨天的文档状态
Get(
  Ref(Collection("users"), "123456"),
  TimeSubtract(Now(), 1, "day")
)

二、Paginate分页 #

2.1 基本分页 #

javascript

// 分页查询所有文档
Paginate(Documents(Collection("users")))

// 设置每页大小
Paginate(
  Documents(Collection("users")),
  { size: 10 }
)

2.2 分页结果 #

javascript

// 分页返回格式
{
  data: [
    Ref(Collection("users"), "1"),
    Ref(Collection("users"), "2"),
    Ref(Collection("users"), "3")
  ],
  after: Ref(Collection("users"), "3"),
  before: null
}

2.3 游标分页 #

javascript

// 获取下一页
Paginate(
  Documents(Collection("users")),
  {
    size: 10,
    after: Ref(Collection("users"), "last_id")
  }
)

// 获取上一页
Paginate(
  Documents(Collection("users")),
  {
    size: 10,
    before: Ref(Collection("users"), "first_id")
  }
)

2.4 分页选项 #

javascript

// 完整分页选项
Paginate(
  Match(Index("all_users")),
  {
    size: 20,                    // 每页大小
    after: cursor,               // 下一页游标
    before: cursor,              // 上一页游标
    sources: true,               // 包含源信息
    events: false                // 包含事件信息
  }
)

三、索引查询 #

3.1 Match查询 #

javascript

// 单条件查询
Match(Index("users_by_email"), "tom@example.com")

// 多条件查询
Match(
  Index("orders_by_user_status"),
  "user_001",
  "pending"
)

// 获取匹配的文档
Get(Match(Index("users_by_email"), "tom@example.com"))

3.2 分页索引查询 #

javascript

// 分页获取索引结果
Paginate(
  Match(Index("users_by_status"), "active"),
  { size: 20 }
)

// 获取并展开文档
Map(
  Paginate(Match(Index("users_by_status"), "active")),
  Lambda("ref", Get(Var("ref")))
)

3.3 范围查询 #

javascript

// 数值范围查询
Paginate(
  Range(
    Match(Index("products_by_price")),
    [10],      // 最小值
    [100]      // 最大值
  )
)

// 日期范围查询
Paginate(
  Range(
    Match(Index("orders_by_date")),
    [Time("2024-01-01T00:00:00Z")],
    [Time("2024-12-31T23:59:59Z")]
  )
)

四、条件过滤 #

4.1 Filter过滤 #

javascript

// 过滤文档
Filter(
  Paginate(Documents(Collection("users"))),
  Lambda("ref",
    Let(
      { doc: Get(Var("ref")) },
      Equals(Select(["data", "status"], Var("doc")), "active")
    )
  )
)

// 复杂过滤
Filter(
  Paginate(Documents(Collection("products"))),
  Lambda("ref",
    Let(
      { doc: Get(Var("ref")) },
      And(
        GT(Select(["data", "price"], Var("doc")), 100),
        LT(Select(["data", "stock"], Var("doc")), 10)
      )
    )
  )
)

4.2 多条件过滤 #

javascript

// 多条件组合过滤
Filter(
  Paginate(Documents(Collection("users"))),
  Lambda("ref",
    Let(
      { doc: Get(Var("ref")) },
      And(
        Equals(Select(["data", "status"], Var("doc")), "active"),
        GTE(Select(["data", "age"], Var("doc")), 18),
        LTE(Select(["data", "age"], Var("doc")), 65),
        ContainsValue(
          Select(["data", "roles"], Var("doc")),
          "admin"
        )
      )
    )
  )
)

五、集合操作 #

5.1 Union并集 #

javascript

// 获取多个条件的并集
Paginate(
  Union(
    Match(Index("users_by_role"), "admin"),
    Match(Index("users_by_role"), "moderator")
  )
)

5.2 Intersection交集 #

javascript

// 获取多个条件的交集
Paginate(
  Intersection(
    Match(Index("users_by_status"), "active"),
    Match(Index("users_by_department"), "engineering")
  )
)

5.3 Difference差集 #

javascript

// 获取差集
Paginate(
  Difference(
    Match(Index("all_users")),
    Match(Index("users_by_status"), "deleted")
  )
)

六、排序 #

6.1 通过索引排序 #

javascript

// 创建排序索引
CreateIndex({
  name: "users_by_created_at",
  source: Collection("users"),
  values: [
    { field: ["data", "createdAt"], order: "desc" },
    { field: ["ref"] }
  ]
})

// 查询结果自动排序
Paginate(Match(Index("users_by_created_at")))

6.2 多字段排序 #

javascript

// 多字段排序索引
CreateIndex({
  name: "products_by_category_price",
  source: Collection("products"),
  terms: [
    { field: ["data", "categoryId"] }
  ],
  values: [
    { field: ["data", "price"], order: "asc" },
    { field: ["data", "name"] },
    { field: ["ref"] }
  ]
})

6.3 内存排序 #

javascript

// 使用Sort函数（小数据量）
Sort(
  Map(
    Paginate(Documents(Collection("users")), { size: 100 }),
    Lambda("ref",
      Let(
        { doc: Get(Var("ref")) },
        {
          name: Select(["data", "name"], Var("doc")),
          age: Select(["data", "age"], Var("doc"))
        }
      )
    )
  ),
  Lambda("a", "b",
    LT(Select("age", Var("a")), Select("age", Var("b")))
  )
)

七、Map展开 #

7.1 展开引用 #

javascript

// 展开文档引用
Map(
  Paginate(Documents(Collection("users"))),
  Lambda("ref", Get(Var("ref")))
)

7.2 选择字段 #

javascript

// 只返回需要的字段
Map(
  Paginate(Documents(Collection("users"))),
  Lambda("ref",
    Let(
      { doc: Get(Var("ref")) },
      {
        id: Select(["ref", "id"], Var("doc")),
        name: Select(["data", "name"], Var("doc")),
        email: Select(["data", "email"], Var("doc"))
      }
    )
  )
)

7.3 展开关联 #

javascript

// 展开关联文档
Map(
  Paginate(Match(Index("all_orders"))),
  Lambda("orderRef",
    Let(
      {
        order: Get(Var("orderRef")),
        userRef: Select(["data", "user"], Var("order")),
        user: Get(Var("userRef"))
      },
      {
        orderNumber: Select(["data", "orderNumber"], Var("order")),
        total: Select(["data", "total"], Var("order")),
        userName: Select(["data", "name"], Var("user")),
        userEmail: Select(["data", "email"], Var("user"))
      }
    )
  )
)

八、聚合查询 #

8.1 Count计数 #

javascript

// 计数
Count(Documents(Collection("users")))

// 条件计数
Count(Match(Index("users_by_status"), "active"))

// 分组计数
Map(
  Paginate(Documents(Collection("users"))),
  Lambda("ref",
    Let(
      { doc: Get(Var("ref")) },
      {
        status: Select(["data", "status"], Var("doc")),
        count: Count(
          Match(
            Index("users_by_status"),
            Select(["data", "status"], Var("doc"))
          )
        )
      }
    )
  )
)

8.2 Reduce归约 #

javascript

// 计算总和
Reduce(
  Map(
    Paginate(Match(Index("all_orders"))),
    Lambda("ref",
      Select(["data", "total"], Get(Var("ref")))
    )
  ),
  Lambda(
    ["acc", "val"],
    Add(Var("acc"), Var("val"))
  ),
  0
)

九、嵌套查询 #

9.1 嵌套字段查询 #

javascript

// 查询嵌套字段
Let(
  {
    doc: Get(Ref(Collection("users"), "123456"))
  },
  {
    name: Select(["data", "name"], Var("doc")),
    city: Select(["data", "address", "city"], Var("doc"), "Unknown"),
    country: Select(["data", "address", "country"], Var("doc"), "Unknown")
  }
)

9.2 数组元素查询 #

javascript

// 查询数组中的元素
Let(
  {
    doc: Get(Ref(Collection("products"), "prod_001"))
  },
  {
    name: Select(["data", "name"], Var("doc")),
    firstTag: Select(["data", "tags", 0], Var("doc")),
    allTags: Select(["data", "tags"], Var("doc"))
  }
)

9.3 深度嵌套查询 #

javascript

// 深度嵌套关联查询
Let(
  {
    order: Get(Ref(Collection("orders"), "order_001")),
    user: Get(Select(["data", "user"], Var("order"))),
    items: Map(
      Select(["data", "items"], Var("order")),
      Lambda("itemRef", Get(Var("itemRef")))
    )
  },
  {
    orderNumber: Select(["data", "orderNumber"], Var("order")),
    total: Select(["data", "total"], Var("order")),
    user: {
      name: Select(["data", "name"], Var("user")),
      email: Select(["data", "email"], Var("user"))
    },
    items: Map(
      Var("items"),
      Lambda("item",
        Select(["data", "name"], Var("item"))
      )
    )
  }
)

十、查询优化 #

10.1 使用索引 #

javascript

// 好的做法：使用索引
Paginate(Match(Index("users_by_email"), "tom@example.com"))

// 避免：全表扫描
Filter(
  Paginate(Documents(Collection("users"))),
  Lambda("ref",
    Equals(
      Select(["data", "email"], Get(Var("ref"))),
      "tom@example.com"
    )
  )
)

10.2 限制返回字段 #

javascript

// 只获取需要的字段
Map(
  Paginate(Match(Index("users_by_status"), "active")),
  Lambda("ref",
    Let(
      { doc: Get(Var("ref")) },
      {
        id: Select(["ref", "id"], Var("doc")),
        name: Select(["data", "name"], Var("doc"))
      }
    )
  )
)

10.3 批量获取 #

javascript

// 批量获取多个文档
Map(
  [
    Ref(Collection("users"), "1"),
    Ref(Collection("users"), "2"),
    Ref(Collection("users"), "3")
  ],
  Lambda("ref", Get(Var("ref")))
)

十一、实际应用示例 #

11.1 用户列表查询 #

javascript

// 分页获取用户列表
Let(
  {
    page: Paginate(
      Match(Index("users_by_status"), "active"),
      { size: 20 }
    ),
    users: Map(
      Var("page"),
      Lambda("ref",
        Let(
          { doc: Get(Var("ref")) },
          {
            id: Select(["ref", "id"], Var("doc")),
            name: Select(["data", "name"], Var("doc")),
            email: Select(["data", "email"], Var("doc")),
            createdAt: Select(["data", "createdAt"], Var("doc"))
          }
        )
      )
    )
  },
  {
    data: Var("users"),
    after: Select(["after"], Var("page")),
    before: Select(["before"], Var("page"))
  }
)

11.2 订单搜索 #

javascript

// 多条件订单搜索
Let(
  {
    userId: "user_001",
    status: "pending",
    startDate: Time("2024-01-01T00:00:00Z"),
    endDate: Time("2024-12-31T23:59:59Z")
  },
  Paginate(
    Intersection(
      Match(Index("orders_by_user"), Var("userId")),
      Match(Index("orders_by_status"), Var("status")),
      Range(
        Match(Index("orders_by_date")),
        [Var("startDate")],
        [Var("endDate")]
      )
    ),
    { size: 50 }
  )
)

11.3 产品搜索 #

javascript

// 产品搜索与过滤
Let(
  {
    categoryId: "cat_001",
    minPrice: 10,
    maxPrice: 1000
  },
  Map(
    Filter(
      Paginate(
        Match(Index("products_by_category"), Var("categoryId")),
        { size: 100 }
      ),
      Lambda("ref",
        Let(
          { doc: Get(Var("ref")) },
          And(
            GTE(Select(["data", "price"], Var("doc")), Var("minPrice")),
            LTE(Select(["data", "price"], Var("doc")), Var("maxPrice")),
            GT(Select(["data", "stock"], Var("doc")), 0)
          )
        )
      )
    ),
    Lambda("ref", Get(Var("ref")))
  )
)

十二、总结 #

查询文档要点：

操作	说明
Get	获取单个文档
Paginate	分页查询
Match	索引匹配
Filter	条件过滤
Map	映射展开
Range	范围查询

下一步，让我们学习更新文档！