C# MongoDb Driver Filter 使用集合中的嵌套屬性

Question

我有以下類結構：

public class QuoteRequestInfo
{
      . . . 
    public LocationInfo LocationInfo {get;set;}
     . . .
}

LocationInfo有一個停靠站集合，它將始終包含 2 個停靠站：

public class LocationInfo
{
    . . . 
    public IEnumerable<Stop> Stops{get;set};
     . . .
}

Stop具有以下屬性：

public class Stop
{
    . . . 
    public string StateName {get;set};
     . . .
}

我正在嘗試通過過濾多個州名稱來搜索QuoteRquestInfos集合，如下所示：

var states = new List<string> {"VA"}
var filter =  Builders<QuoteRequestInfo>.Filter.In(r => r.LocationInfo.Stops.First().StateCode, states)
var quotes = await collection.Find(filter).ToListAsync();

這是返回一個空過濾器並且不匹配任何內容？ 我應該如何將表達式傳遞給 In Filter ？ 有任何想法嗎 ？

Answer 1

有很多方法，例如：

        var states = new List<string> { "VA" };
        var quotes = coll.AsQueryable()
            .Select(c =>
                new {
                    Previous = new QuoteRequestInfo { LocationInfo = c.LocationInfo }, // this partocular line saves the previous document
                    StoredFirst = c.LocationInfo.Stops.First().StateName }) // save a flag about first stop since call it in the same construction with `Where` is not supported via typed way
            .Where(f => states.Contains(f.StoredFirst))
            .Select(c => c.Previous)
            .ToList();