选择查询以使用linq根据不同的值获取所有值

Question

I have n number of services and under each service there will be 2 routes(some times more than 2). Under each route there are n number of stops. I am getting values from db as a table in below column order ServiceId, Service Name,serviceLine color,RouteId, Route Name, Stop Id, Stop Name, Latitude, Longitude.

I want to convert it an object list of below format

  public class Service { public string ServiceId { get; set; } public string ServiceName { get; set; } public string ServiceLineColor { get; set; } public List<RouteData> RouteList { get; set; } } public class RouteData { public string RouteId { get; set; } public string RouteCode { get; set; } public string RouteName { get; set; } public List<StopData> stopList { get; set; } } public class StopData { public string StopCode { get; set; } public string StopName { get; set; } public string Latitude { get; set; } public string Longitude { get; set; } public string StopType { get; set; } } 

Is there any easy way in linq to convert data in to below format? I wanted to avoid looping.. since i am getting nearly 1k records from db. Please help me to solve this issue.

Or is it best to use db calls to format data. i didn't prefer that because if there is 50 services i need to do 50 db calls and again have to do data formatting logic.

Answer 1

To avoid looping over the data structure each time, you could build up additional dictionaries that provide fast access of the objects by id:

var myServiceIndex = new Dictionary<string, Service>()
var myRouteDataIndex = new Dictionary<string, RouteData>()

Service service;
RouteData routData;

foreach (var record in databaseRecords)
{
    if (myRouteDataIndex.TryGetValue(record.RouteId, out route))
    {
        // add stop data
    }
    else if (myServiceIndex.TryGetValue(record.ServiceId, out service)
    {
        // add route data
        // add stop data 
    }
    else
    {
        // add service
        // add route data
        // add stop data 
    }
}

Answer 2

You have a number of stops, and for each stop entry in database you have to map it to a C# object. In this case, looping is inevitable, as far as I see. Linq, and eg. entity framework, use looping internally.

One option is to use entity framework or Linq to SQL . It will give you strong type classes representing each DB table. But you have to change your DB schema and use foreign keys to link service, route, and stops.

C# code would look exactly like yours, which is auto generated by entity framework and in-sync with DB schema.

Second option is to convert manually . Note, your current schema doesn't complient with Third normal form . If you don't want to change your schema, you could read and generate them using group by clause.