How to Apply Different Filters for Each yField in MongoDB Aggregation Pipeline in Blazor WASM?

I'm building a Blazor WASM application that generates charts using MongoDB. My current implementation aggregates data from a MongoDB collection and supports multiple yFieldvalues for grouping and aggregation.

The current code works for a single match filter that applies to all fields, but I need to add individual filters for each yField. Here's the relevant part of my code:

    [Authorize]    [HttpPost("GetChartDataAsync")]    public async Task<string> GetChartData(chartclass chart)    {        var collection = GetMyDb().MDB.GetCollection<BsonDocument>("d_sales_date");        var groupStage = new BsonDocument{    { "_id", $"${chart.xfield}" }};        foreach (var y in chart.yfield)        {            Aggregations aggregate = Aggregations.Sum;            var aggregationOperator = aggregate switch            {                Aggregations.Sum => "$sum",                Aggregations.Min => "$min",                Aggregations.Max => "$max",                Aggregations.Average => "$avg",                _ => "$sum"            };            //y field filters            groupStage.Add(y.name, new BsonDocument(aggregationOperator, $"${y.name}"));        }        var pipeline = new List<BsonDocument>{    new BsonDocument("$group", groupStage)};        var results = await collection.Aggregate<BsonDocument>(pipeline).ToListAsync();        return results.ToJson();    }    public class chartclass    {        public string xfield { get; set; } = "";        public List<YField> yfield { get; set; } = new();    }    public class YField    {        public string name { get; set; } = "";        public BsonDocument filter { get; set; } = new();        public Aggregations aggregate { get; set; } = Aggregations.Sum;    }

I need to allow each yField to have its own filter (defined in yField.filter) so that I can match specific subsets of data for each aggregation.

For example:

For yField1, apply a match filter where fieldA > 100.For yField2, apply a match filter where fieldB == "value".

Desired Behavior:

I want to modify the pipeline to include conditional $match stages for each yField before adding its aggregation logic to the $group stage.

Any guidance or suggestions would be greatly appreciated.