Delete each element of nested array of documents if they don't match my query

Working with Data
1

Hi :raising_hand_woman:t6:

My database structure is like this:

{
  rootField: "value",
  anotherRootField: "value1",
  products:[
     {
       productName: "p1_name",
       currencies: [
         {
            currencyName: "p1c1_name"
         },
         {
           currencyName: "p1c2_name" 
         }
       ]
     },
     {
       productName: "p2_name",
       currencies: [
         {
          currencyName: "p2c1_name"
         },
         {
          currencyName: "p2c2_name"
         },
       ]
     },
   ],
   ships: [
     {
      shipDate: "shipDate"
     },
     ...
   ]
}

For some reason users can send different queries which means I don’t know what exactly they want and also they can search for each level of my document.

My goal is to process the query and return the result as a microsoft excel file. for that I need to remove products/currencies/ships if they don’t match the query. for example for this query:

{
 productName: "p1_name",
}

I need something like this:

{
  rootField: "value",
  anotherRootField: "value1",
  products:[
     {
       productName: "p1_name",
       currencies: [
         {
            currencyName: "p1c1_name"
         },
         {
           currencyName: "p1c2_name" 
         }
       ]
     }
   ]
}

or if search for currency:

{
 currencyName: "p2c1_name",
}

I need this:

{
  rootField: "value",
  anotherRootField: "value1",
  products:[
     {
       productName: "p2_name",
       currencies: [
         {
          currencyName: "p2c1_name"
         },
       ]
     },
   ]
}

I have a hard time to understanding the aggregation framework and this is what I working on:

await Proforma.aggregate([
        { $match: { rootField: "value" } },// sample query
        { $unwind: "$products" },
        { $match: { "products.productName": "p1_name" } }, // sample query
        { $unwind: "$products.currencies" },
        { $match: { "products.currencies.currencyName": "p1c1_name"}}, // sample query
        {  // back to array
          $group: {
            _id: { _id: "$_id", product__id: "$products._id" },
            currencies: { $push: "$products.currencies" },
          },
        },
        { // back to array
          $group: {
            _id: "$_id._id",
            products: {
              $push: {
                _id: "$id.product__id",
                currencies: "$currencies",
              },
            },
          },
        },
      ]);

As I said my query could be very complex and contains multiple fields from root, products, currencies and ships so I don’t know is this works for my situations or not but my current problem is my rootFields get ignored from the result. I just want to filter nested fields and have rootFields untouched.

and also I don’t know how to add ships to this query

also filter does not work for me because sometimes my conditions contain a lot of nested $or and $and and i get this error:

MongoDB aggregate error: expression must have exactly one field
2

Much simpler if you make separate queries for each type of query.
How is user indicating query? A web form? In what environment?
Maybe you can identify the type of query in your web language and have an array of 3 different queries to suit the 3 different cases.