Update mongodb

Src/Asp.NetCore2/MongoDb.Ado.data/ExecuteDbDataReaderItems/QueryFindHandler.cs

@@ -0,0 +1,43 @@
+using MongoDB.Bson;
+using MongoDB.Driver;
+using System;
+using System.Collections.Generic;
+using System.Data.Common;
+using System.Text;
+
+namespace MongoDb.Ado.data 
+{
+    public class QueryFindHandler : IQueryHandler
+    {
+        public DbDataReader Find(IMongoCollection<BsonDocument> collection, BsonValue doc)
+        {
+            BsonDocument filter;
+            BsonDocument projection = null;
+
+            if (doc.IsBsonArray)
+            {
+                var array = doc.AsBsonArray;
+                filter = array.Count > 0 ? array[0].AsBsonDocument : new BsonDocument();
+                if (array.Count > 1)
+                    projection = array[1].AsBsonDocument;
+            }
+            else if (doc.IsBsonDocument)
+            {
+                filter = doc.AsBsonDocument;
+            }
+            else
+            {
+                throw new ArgumentException("Invalid JSON format for MongoDB find operation.");
+            }
+
+            var findFluent = collection.Find(filter);
+
+            if (projection != null)
+                findFluent = findFluent.Project<BsonDocument>(projection);
+
+            var cursor = findFluent.ToCursor(); // 已包含 filter + projection 的结果
+
+            return new MongoDbIAsyncCursorDataReader(cursor); // 你要确保这个类支持逐行读取 BsonDocument
+        }
+    }
+}