How to add parent name with their name using parent Id - node.js

Question

I have following array which is saved in Database. i want to modify it to display like following which show their hierarchic with parent in localeName key.
var allLocales = [
{
id: 123,
localeName: 'Test',
parentId: null
},
{
id: 456,
localeName: 'Test 1',
parentId: 123
},
{
id: 789,
localeName: 'Test 2',
parentId: 456
}
]
I want to change above array to following array by changing their display name like this using their parents.:
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

Try this aggregation if you are using mongo 3.4+
you can use $graphLookup for hierarchical queries $graphLookup
db.locales.aggregate(
[
{$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()
collection
> 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 }
>
result
> 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
}

Answer 2

You need to make recursive function to solve this problem.
I made like below and tested.
Please see the function.
var allLocales = [
{ id: 123, localeName: 'Test', parentId: null },
{ id: 456, localeName: 'Test 1', parentId: 123 },
{ id: 789, localeName: 'Test 2', parentId: 456 }
];
function nameRecursion(element) {
if(element.parentId == null) {
return element.localeName
}else {
var parent = allLocales.find(item => item.id === element.parentId);
return nameRecursion(parent) + " -> " + element.localeName;
}
}
var newArray = allLocales.map(a => Object.assign({}, a));
for(var i=0; i<allLocales.length; i++){
newArray[i].localeName = nameRecursion(allLocales[i]);
}
console.log(allLocales);
console.log(newArray);