C# console app Collection does not contain definition for object class and no accessible extension method

Question

I've been trying to nest a set of objects inside my json array and I can't seem to get it to work.

{
         "events":[
            {
               "event_name":"purchase",
               "event_params":{
                  "product_id":"AGH210070",
                  "unit_price":990.9,
                  "currency":"USD"
               }
            },
            {
               "event_name":"purchase",
               "event_params":{
                  "product_id":"AGH210020",
                  "unit_price":890,
                  "currency":"EUR"
               }
            }
         ]
}

Here's the code I'm using to do it:

                            using (SqlConnection con = new SqlConnection(connString))
                            {
                                string transactionShipQuery = String.Format(@"randomsqlquery");

                                SqlCommand shipsCmd = new SqlCommand(transactionShipQuery, con);

                                con.Open();

                                SqlDataReader ships = shipsCmd.ExecuteReader();

                                while (ships.Read())
                                {
                                    event_name = ships.GetString(0);

                                    model.Events.Add(new EventModel
                                    {
                                        Event_name = event_name

                                    });
                                }
                            }

                            using (SqlConnection con = new SqlConnection(connString))
                            {
                                string transactionShipQuery = String.Format(@"sqlquery");

                                SqlCommand shipsCmd = new SqlCommand(transactionShipQuery, con);

                                con.Open();

                                SqlDataReader ships = shipsCmd.ExecuteReader();

                                while (ships.Read())
                                {
                                    product_id = ships.GetString(0);
                                    unit_price = ships.GetDecimal(1);
                                    currency = ships.GetString(2);

                                    model.Events.Event_params.Product_id = product_id;
                                    model.Events.Event_params.Unit_price = product_id;
                                    model.Events.Event_params.Currency = product_id;


                                }
                            }

                            var myJson = JsonConvert.SerializeObject(model, Formatting.Indented);
                            Console.WriteLine(myJson);

And here is my class structure:

[Serializable]
    public class model
    {

        [JsonProperty("events")]
        public Collection<EventModel> Events = new Collection<EventModel>();
    }

    public class EventModel
    {
        [JsonProperty("event_name")]
        public string Event_name { get; set; }

        [JsonProperty("event_params")]
        public ProductModel Event_params { get; set; } = new ProductModel();


    }

    public class ProductModel
    {
        [JsonProperty("product_id")]
        public string Product_id { get; set; }

        [JsonProperty("unit_price")]
        public decimal Unit_price { get; set; }

        [JsonProperty("currency")]
        public string Currency { get; set; }

    }

I can't seem to find a way to call event_params inside of the events collection without getting an error saying the collection does not contain a definition for it.

Answer 1

model.Events.Event_params

you are trying to access Event_params on a collection instead of the actual object you want.

you could for example change it to:

int i = 0
while (ships.Read())
{
    product_id = ships.GetString(0);
    unit_price = ships.GetDecimal(1);
    currency = ships.GetString(2);
    
    model.Events[i].Event_params.Product_id = product_id;
    model.Events[i].Event_params.Unit_price = product_id;
    model.Events[i].Event_params.Currency = product_id;
    i++;

}

Answer 2

In your second using statement you are using Events collection as-if it is an object. You have to selecte the correct Event from the collection and then assing properties to it. See below code:

class Program
    {
        static void Main(string[] args)
        {

            var _model = new model();

            //First using statement creates an event
            _model.Events.Add(new EventModel
            {
                Event_name = "event_name"
            });


            //First using statement search for appropriate Event and assign values, I am sure you have Event name while running second SQl query
            var _event = _model.Events.FirstOrDefault(x => x.Event_name == "event_name");
            if (_event != null)
            {
                _event.Event_params.Product_id = "product_id";
                _event.Event_params.Unit_price = (decimal)1.30;
                _event.Event_params.Currency = "USD";
            }


            var myJson = JsonConvert.SerializeObject(_event, Formatting.Indented);
            Console.WriteLine(myJson);

            Console.ReadLine();
        }
    }