使用实体框架从嵌套表获取数据

Question

First of all this is my first question in the forum so please excuse me for any writing mistake.

I have 4 tables

attaching the table diagram

What I want is to get list of attraction name joining 'tblattraction' with 'tblattractionmaster' and count of the exact attraction for each place from 'tblattractions' using 'locationid' , I am using entity framework but don't know how to do that,

Disclaimer: Each location can consist Multiple Places Each Place can consist Multiple Attractions

What I have tried

 return context.tblLocationMasters.Select(t => new details()
                {
                    locationid = t.LocationId,
                    locationname = t.LocationName,
                    attractions =t.tblPlaces.SelectMany(a => a.tblAttractions).Select(b => new attractions(){
                        AttractionName=b.tblAttractionMaster.attractionname//(Not working),
                        TotalAttractions=0//???
                    }).ToList()
                }).ToList();

Answer 1

I recreated your model (slightly different) using Code First. I came up with the following structure:

public class Location
{
    public int LocationId { get; set; }

    public string LocationName { get; set; }

    public ICollection<Place> Places { get; set; }
}

public class Place
{
    public int PlaceId { get; set; }

    public string PlaceName { get; set; }

    public int LocationId { get; set; }

    public Location Location { get; set; }

    public ICollection<AttractionPlace> Attractions { get; set; }
}

public class Attraction
{
    public int AttractionId { get; set; }

    public string AttractionName { get; set; }
}

public class AttractionPlace
{
    public int AttractionPlaceId { get; set; }

    public int PlaceId { get; set; }

    public Place Place { get; set; }

    public int AttractionId { get; set; }

    public Attraction Attraction { get; set; }
}

Then, I could get the results in the way you needed with the following query:

var query = (from loc in db.Locations
             join pla in db.Places.Include(x => x.Attractions) on loc.LocationId equals pla.LocationId
             let count = pla.Attractions.Count()
             select new
             {
                 loc.LocationId,
                 loc.LocationName,
                 Attractions = pla.Attractions.Select(z => new
                 {
                     pla.PlaceName,
                     z.AttractionId,
                     z.Attraction.AttractionName
                 }),
                 AttractionsByPlaceCount = count
             });

The query above returns data in this format

Just a side note though: I didn't went further to see the performance of this query. The SQL generated by Linq wasn't that bad, but you should consider analyzing it before actually using it in production.