嵌套对象上的 Mongo 索引 [英] Mongo indexing on nested object

问题描述

我的mongodb集合的结构是这样的，

My mongodb collection's structure looke like this,

{
paymentTree: {
t1: { from: "id-123", to: "id-2334", },
t2: { from: "id-1443", to: "id-567", },
t3: { from: "id-76567", to: "id-2334", },
tn: { from: "id-12n", to: "id-233n", }
}

如何在paymentTree中索引字段'to'?

How can index field 'to' in paymentTree?

推荐答案

目前无法在动态对象键中创建索引，

Currently it is not possible to create index in dynamic object key,

如果您无论如何都想实现，那么我建议您是否可以将架构结构转换为 属性模式,

If you want to achieve anyway then I would suggest if you could transform your schema structure to The Attribute Pattern,

• 将paymentTree对象类型改为数组类型，
• 将对象更改为键值对中的数组，k 用于树的动态键，v 用于{ from, to } 对象，

• change paymentTree object type to array type,
• change object to array in key-value pairs, k for tree's dynamic key and v for { from, to } object,

{
  paymentTree: [
      {
        "k": "t1",
        "v": { "from": "id-123", "to": "id-2334" }
      },
      {
        "k": "t2",
        "v": { "from": "id-1443", "to": "id-567" }
      },
      {
        "k": "t3",
        "v": { "from": "id-76567", "to": "id-2334" }
      },
      {
        "k": "tn",
        "v": { "from": "id-12n", "to": "id-233n" }
      }
  ]
}

这种结构的好处:

• 创建多键单字段索引 在 to 上:

  Benefits of this structure:

  • Create Multikey Single Field Index on to:

    您可以在包含嵌套对象的数组字段上创建多键索引，

    You can create multikey indexes on array fields that contain nested objects,

    db.collection.createIndex({ "paymentTree.v.to": 1 });
    

  • 创建k 和 to 上的>多键复合索引:

  • Create Multikey Compound Index on k and to:

    db.collection.createIndex({ "paymentTree.k": 1, "paymentTree.v.to": 1 });
    

  • 将对象推送到数组:

    您可以在更新方法(updateOne 和 updateMany)中使用 $push 将对象插入到 paymentTree 数组.

    You can insert object to paymentTree array using $push in update methods (updateOne and updateMany).

    从数组中拉取对象:

    您可以在更新方法(updateOne 和 updateMany)中使用 $pull 从支付树数组中删除基于 k 的特定对象).

    You can remove specific object on the base of k from paymentTree array using $pull in update methods (updateOne and updateMany).

    匹配条件:

    您可以使用条件运算符轻松匹配条件，

    You can easily match conditions using conditional operators,

    • 示例 1:

    { "paymentTree.k": "t1" } 
    

    • 例 2:

    { "paymentTree.v.to": "id-2334" } // or { "paymentTree.v.from": "id-123" }
    

    • 例 3:

    { 
      "paymentTree": {
        "$elemMatch": {
          "k": "t1",
          "v.to": "id-2334"   // or "v.from": "id-123"
        }
      }
    } 
    

    • 我如何轻松选择诸如 paymentTree.t1、..:

      • 查询中:
        • 有一个操作符叫做$arrayToObject，你可以在投影阶段将 paymentTree 数组转换为对象($project、$addFields、$set)参见 游乐场、
        • find() 和 findOne() 投影可以接受来自 MongoDB v4.4 投影的聚合表达式和语法，与聚合的 $project 阶段一致，
        • In Query:
          • There is a operator called $arrayToObject, you can convert paymentTree array to object in projection stages ($project, $addFields, $set) see Playground,
          • The find() and findOne() projection can accept aggregation expressions and syntax from MongoDB v4.4 projection consistent with aggregation’s $project stage,
          • 您需要将 peymentTree 数组转换为客户端语言(go、node.js 等)中的对象格式.
          • You need to convert peymentTree array to object format in your client side language (go, node.js, etc.).

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