Mongodb, how to use findOne method in javascript map

Question

I'm having a problem where Mongodb findOne si not working in mapping throug array of object is returning [ Promise { } ]

const data = [
{
  GLAccountId: 5fac4225dce5f459e40117f6,
  Balance: 0
},
{
  GLAccountId: 5fac4225dce5f459e401423,
  Balance: 0
}
]

let glAccount= "";
let result = data.map(async(item) => {
     glAccount = await GL_Account.findOne({ _id: item.GLAccountId});
     return {
        glAccount: glAccount.title,
        balance: glAccount.balance
      }
});
console.log(result);

can you guys help me with? Thanks.

Answer 1

Instead of iterating the data array and make multiple findOne calls, create a query from the array and use find() or aggregate() methods to make a single query with the custom projections as follows:

const data = [
    {
        GLAccountId: 5fac4225dce5f459e40117f6,
        Balance: 0
    },
    {
        GLAccountId: 5fac4225dce5f459e401423,
        Balance: 0
    }
]

const ids = data.map(item => item.GLAccountId)
let result = await GL_Account.find({ _id: { $in: ids } })
    .lean()
    .map(glAccount => ({
        glAccount: glAccount.title,
        balance: glAccount.balance
    }))

or using aggregate() :

let result = await GL_Account.aggregate([
    { $match: { 
        _id: { $in: ids.map(id => mongoose.Types.ObjectId(id)) },    
    } },
    { $project: {
        _id: 0,
        glAccount: '$title',
        balance: 1
    } }
]).exec()