MongoDB汇总会计信息

Question

I am completely new to MongoDB aggregation. I currently, have a collection in which I save a few account names:

accounts : _id: ObjectId; name: String

Example: Items: ObjectId(...) "Bank account" etc

On top of that, I have a journal collection, in which I store accounting journal entries. They look the following:

journals : _id: ObjectId, debit: (Ref to accounts id), credit: (Ref to accounts id); amount

The idea is, that I save accounting entries like the following: Debit: (Id of "Bank Account"), Credit: (Id of "Share Capital")

Now, I am trying to use the aggregate get the total debit, total credit, and total sum (debit-credit) for all account types.

Now, I kind of this to work for only one specific account type:

db.journals.aggregate(
{ $project: {
    _id: 0,
    PosSentiment: {$cond: [{$eq: ['$debit',  ObjectId("5a809cf86ce518470ec92502")]}, '$amount', 0]},
    NegSentiment: {$cond: [{$eq: ['$credit',  ObjectId("5a809cf86ce518470ec92502")]}, '$amount', 0]}
}},
{ $group: {
    _id: 0,
    debit: {$sum: '$PosSentiment'},
    credit: {$sum: '$NegSentiment'}
}});

Unfortunately, this only gives me credit and debit for one type of account that I specific in the ObjectId, I don't have the total and I have to run this for every account.

Is there a possibility to use aggregates to end up with a result like this [{_id: ..., name (from account collection), totaldebit, totalcredit, total}]?

Thank you very much!

Answer 1

You can use below aggregation.

db.journals.aggregate([
  {"$lookup":{
    "from":"accounts",
    "localField":"debit",
    "foreignField":"_id",
    "as":"debit"
  }},
  {"$lookup":{
    "from":"accounts",
    "localField":"credit",
    "foreignField":"_id",
    "as":"credit"
  }},
  {"$project":{
     "data":[
       {name:"$debit","type":"debit"},
       {name:"$credit","type":"credit"}
    ],
    "amount":1
   }},
  {"$unwind":"$data"},
  {"$group":{
    "_id":{"account":{"$arrayElemAt":["$data.name",0]},"type":"$data.type"},
    "total":{"$sum":"$amount"}
  }},
  {"$group":{
    "_id":"$_id.account._id",
    "name":{"$first":"$_id.account.name"},
    "balances":{$push:{"type":"$_id.type","total":"$total"}},
    "alltotal":{"$sum":"$total"}
  }}
])