node.js - 如何使用家长 ID 添加家长姓名及其姓名

Question

我有以下数组，保存在数据库中。我想修改它以如下所示显示其与 localeName 键中的父级的层次结构。

var allLocales = [
{
    id: 123,
    localeName: 'Test',
    parentId: null
},
{
    id: 456,
    localeName: 'Test 1',
    parentId: 123
},
{
    id: 789,
    localeName: 'Test 2',
    parentId: 456
}
]

我想通过使用其父级更改其显示名称来将上面的数组更改为以下数组。:

allLocales = [
{
    id: 123,
    localeName: 'Test',
    parentId: null
},
{
    id: 456,
    localeName: 'Test > Test 1',
    parentId: 123
},
{
    id: 789,
    localeName: 'Test > Test 1 > Test 2',
    parentId: 456
}
]

Answer 1

如果您使用的是 mongo 3.4+，请尝试此聚合

您可以使用$graphLookup进行分层查询$graphLookup

db.locales.aggregate(
    [
        {$graphLookup : {
            from : "locales",
            startWith : "$parentId",
            connectFromField : "parentId",
            connectToField : "id",
            as : "parents"
            }
        },
        {$addFields : {localeName : {$substr : [{$concat : [{$reduce : {input : "$parents", initialValue : "", in : {$concat : ["$$value", " > ", "$$this.localeName"]}}}, " > " ,"$localeName"] }, 3 , 1000]}}},
        {$project : {parents : 0}}
    ]
).pretty()

收藏

> db.locales.find()
{ "_id" : ObjectId("5a73dead0cfc59674782913a"), "id" : 123, "localeName" : "Test", "parentId" : null }
{ "_id" : ObjectId("5a73dead0cfc59674782913b"), "id" : 456, "localeName" : "Test 1", "parentId" : 123 }
{ "_id" : ObjectId("5a73dead0cfc59674782913c"), "id" : 789, "localeName" : "Test 2", "parentId" : 456 }
> 

结果

> db.locales.aggregate( [ {$graphLookup : { from : "locales", startWith : "$parentId", connectFromField : "parentId", connectToField : "id", as : "parents" } }, {$addFields : {localeName : {$substr : [{$concat : [{$reduce : {input : "$parents", initialValue : "", in : {$concat : ["$$value", " > ", "$$this.localeName"]}}}, " > " ,"$localeName"] }, 3 , 100]}}}, {$project : {parents : 0}} ] ).pretty()
{
    "_id" : ObjectId("5a73dead0cfc59674782913a"),
    "id" : 123,
    "localeName" : "Test",
    "parentId" : null
}
{
    "_id" : ObjectId("5a73dead0cfc59674782913b"),
    "id" : 456,
    "localeName" : "Test > Test 1",
    "parentId" : 123
}
{
    "_id" : ObjectId("5a73dead0cfc59674782913c"),
    "id" : 789,
    "localeName" : "Test > Test 1 > Test 2",
    "parentId" : 456
}