LINQ EF分组和包含例外

Question

Need help in creating LINQ query to group and filter with related entities.

Here is my model classes.

public class Application
    {
        [DisplayName("Application")]
        public int ApplicationId { get; set; }
        [DisplayName("Application")]
        public string Name { get; set; }
        public List<DashboardEntry> DashboardEntries { get; set; }
    }

public class Cluster
    {
        [DisplayName("Cluster")]
        public int ClusterId { get; set; }
        [DisplayName("Cluster")]
        public string Name { get; set; }
    }

[Bind(Exclude = "AlbumId")]
    public class DashboardEntry
    {
        [ScaffoldColumn(false)]
        public int DashboardEntryId { get; set; }        
        public int ClusterId { get; set; }        
        public int ApplicationId { get; set; }        
        public HealthStatusIndicator Status { get; set; }
        public string Incident { get; set; }
        public string Remarks { get; set; }

        public virtual Cluster Cluster { get; set; }
        public virtual Application  Application { get; set; }
    }

Index action method is as follows

public ActionResult Index()
        {
            //var dashboardEntries = db.DashboardEntries.Include(d => d.Application).Include(d => d.Cluster);

            var dashboardEntries = db.DashboardEntries
                                   .Include(d => d.Application)
                                   .Include(d => d.Cluster)                                   
                                   .GroupBy(d => d.Application);

            return View(dashboardEntries.ToList());
        }

In the view, model declaration is as below.

@model IEnumerable<HealthCheckIndex.Models.DashboardEntry>

I'm getting an error

The model item passed into the dictionary is of type 'System.Data.Entity.Infrastructure.DbQuery1[System.Linq.IGrouping2[HealthCheckIndex.Models.Application,HealthCheckIndex.Models.DashboardEntry]]', but this dictionary requires a model item of type 'System.Collections.Generic.IEnumerable`1[HealthCheckIndex.Models.DashboardEntry]'.

If I change the model declaration in view as below, I'm getting a another error that Cluster is not accessible.

@model IEnumerable>

I want to group the dashboard entries into different applications and filter the groups by choosing the max dashboard entry from each group.

Answer 1

The type that you are passing currently to the view does not match the specified type

@model IEnumerable<HealthCheckIndex.Models.DashboardEntry>

Currently you are passing something like a dictionary where the key is Application and the value is a IEnumerable of HealthCheckIndex.Models.DashboardEntry

In order to make it you have one of 2 options:

1. Replace the last line of the controller action with

   return View(dashboardEntries.SelectMany(c=> c).ToList());

2. Change model definition in the view to match the list your returning