MongoDB-聚合深树结构

我想从我的数据库中提取树形图

这是我的结构（总是一个树形图）

我试着做这样的事情

db.test3.aggregate([{
     $lookup: {
         from: "test3",
         localField: "_id",
         foreignField: "_id",
         as: "array"
     }
 }])

但我只是收到了

{ "_id" : ObjectId("59490a250f86a4b4e0cb75b2"), "title" : "a", "array" : [ { "_id" : ObjectId("59490a250f86a4b4e0cb75b2"), "title" : "a", "array" : [ { "_id" : ObjectId("59490a250f86a4b4e0cb75b3") } ] } ] }
{ "_id" : ObjectId("59490a250f86a4b4e0cb75b3"), "title" : "b", "array" : [ { "_id" : ObjectId("59490a250f86a4b4e0cb75b3"), "title" : "b", "array" : [ { "_id" : ObjectId("59490a250f86a4b4e0cb75b4") } ] } ] }
{ "_id" : ObjectId("59490a250f86a4b4e0cb75b4"), "title" : "c", "array" : [ { "_id" : ObjectId("59490a250f86a4b4e0cb75b4"), "title" : "c", "array" : [ { "_id" : ObjectId("59490a250f86a4b4e0cb75b5") }, { "_id" : ObjectId("59490a250f86a4b4e0cb75b6") } ] } ] }
{ "_id" : ObjectId("59490a250f86a4b4e0cb75b5"), "title" : "d", "array" : [ { "_id" : ObjectId("59490a250f86a4b4e0cb75b5"), "title" : "d" } ] }
{ "_id" : ObjectId("59490a250f86a4b4e0cb75b6"), "title" : "e", "array" : [ { "_id" : ObjectId("59490a250f86a4b4e0cb75b6"), "title" : "e", "array" : [ { "_id" : ObjectId("59490a250f86a4b4e0cb75b7") } ] } ] }
{ "_id" : ObjectId("59490a250f86a4b4e0cb75b7"), "title" : "f", "array" : [ { "_id" : ObjectId("59490a250f86a4b4e0cb75b7"), "title" : "f" } ] }

---

但这似乎并没有达到预期效果

根据上述问题中提到的描述，请尝试在MongoDB shell中执行以下聚合查询

db.test3.aggregate(

    // Pipeline
    [
        // Stage 1
        {
            $unwind: {
                path : "$array"
            }
        },

        // Stage 2
        {
            $lookup: {
                "from" : "mycoll",
                "localField" : "array._id",
                "foreignField" : "_id",
                "as" : "arr"
            }
        }

    ]



);

---

根据上述问题中的描述，请尝试在MongoDB shell中执行以下聚合查询

db.test3.aggregate(

    // Pipeline
    [
        // Stage 1
        {
            $unwind: {
                path : "$array"
            }
        },

        // Stage 2
        {
            $lookup: {
                "from" : "mycoll",
                "localField" : "array._id",
                "foreignField" : "_id",
                "as" : "arr"
            }
        }

    ]



);

---

这不是递归的。您应该阅读MongoDB文档。通读一遍。正确设计的结构和搜索根本没有嵌套。这不会递归地工作。您应该阅读MongoDB文档。通读一遍。正确设计的结构和搜索根本没有嵌套。