MongoDB C# Driver Projection of fields

Question

Hi i have a collection In mongoDB that i want to get only part of the fields from it, i created a class that i'm inserting data with to Mongo

ClassCode:

public class  FrameDocument
{

    public ObjectId _id { get; set; }
    public Nullable<System.DateTime> FrameTimeStamp { get; set; }
    public Nullable<int> ActivePick { get; set; }
    public Nullable<int> TraderId { get; set; }
    public Nullable<int> EventCodeId { get; set; }
    public byte[] Frame { get; set; }
    public int ServerUserId { get; set; }
    public int SesionId { get; set; }
    public string TraderName { get; set; }
    public string ServerUserName { get; set; }


}

This is the insert code:

               FrameDocument frameDoc = new FrameDocument();

            frameDoc.Frame = imageBA;
            frameDoc.EventCodeId = 1;
            frameDoc.SesionId = 1;
            frameDoc.FrameTimeStamp = DateTime.Now;
            frameDoc.ServerUserId = (int)toMongoDt.Rows[0]["ServerUserId"];
            frameDoc.TraderId = (int)toMongoDt.Rows[0]["TraderId"];
            frameDoc.ActivePick = (int)toMongoDt.Rows[0]["ActivePick"];
            frameDoc.TraderName = (string)toMongoDt.Rows[0]["TraderName"];
            frameDoc.ServerUserName = (string)toMongoDt.Rows[0]   ["ServerUserName"];
            var mongoCon = "mongodb://127.0.0.1";
            MongoClient client = new MongoClient(mongoCon);
            var db = client.GetDatabase("Video");

            var frameCollection = db.GetCollection<FrameDocument>("Frame");
            frameCollection.InsertOne(frameDoc);

**For now i get all The fields from the collection with this code, But i want to leave the Frame field out of the class, i tried to build different class without this field but i don't know how to not receive the Frame field **

                var collection = db.GetCollection<BsonDocument>("Frame");
            var builder = Builders<BsonDocument>.Filter;
            var filter = builder.Eq("SesionId", 1)
                & builder.Eq("TraderId", 125)
                 & builder.Eq("ServerUserId", 1)
                & builder.Lt("FrameTimeStamp", sing.eDate)
                & builder.Gt("FrameTimeStamp", sing.sDate);

            var result = collection.Find(filter).ToList();

Can anyone help?

Solution 1

please see this:

   _result = _collection.Find(o => o._id == _id)
            .Project<FrameDocumentNoFrameField>  
          (Builders<FrameDocument>.Projection.Exclude(f => f.Frame)).ToList();

where FrameDocumentNoFrameField is a class without Frame field

source here

Solution 2

#Example: Model class

    public class Company
    {
        public string CompanyId { get; set; }
        public string CompanyName { get; set; }
        public List<CompanySettings>{ get; set; }
    }

   [BsonIgnoreExtraElements]
    public class CompanySettings
    {
        public CompanySetupType CompanySetupTypeId { get; set; }
        public List<string> CompanyEmployee{ get; set; }
    }

#Now create a Projection class for which you want to read values

[BsonIgnoreExtraElements]
    public class CompanySettingsProjectionModel
    {  
        public List<CompanySettings> CompanySettings { get; set; }
    }

#After Creating projection,fetch data from mongo using Builders

     public async Task<CompanySettings> GetCompanySettings(string companyId, short CompanySetupTypeId)
        {
            var filter = BaseFilter(accountId);

            var projection = Builders<Company>.Projection
            .Include(x => x.Id)
            .Include(x => x.CompanySettings);

            FindOptions<Company, CompanySettingsProjectionModel> findOptions = new FindOptions<Company, CompanySettingsProjectionModel>()
            {
                Projection = projection
            };

            var companySettings = await (await Collection.FindAsync(filter, findOptions)).FirstOrDefaultAsync();

            if (companySettings != null && companySettings.CompanySettings != null && companySettings.CompanySettings.Any())
            {
                return companySettings.CompanySettings .FirstOrDefault(x => (int)x.CompanySetupTypeId == CompanySetupTypeId);
            }

            return default;
        }