LINQ EF Grouping and Include exception

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.

It's best not to pass EF Models directly to your View. Create a ViewModel that contains the data without navigation properties that the controller creates and passes to your View — Tah, Mar 27 '16 at 07:50
Thanks for the advice. I will ultimately change to this approach but right now my target is to get the app up and running. I'm going to opt the SelectMany(c=>c) for now — kunaguvarun, Mar 27 '16 at 12:24

score 2 · Accepted Answer · edited Mar 27 '16 at 08:51

2

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:

Replace the last line of the controller action with

return View(dashboardEntries.SelectMany(c=> c).ToList());
Change model definition in the view to match the list your returning

edited Mar 27 '16 at 08:51

Vojtěch Dohnal

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answered Mar 27 '16 at 08:43

Ali Hajahmed

184
3

Thanks for SelectMany(c=>c). It returns all the records grouped into Applications. How do I filter the groups based on max of dashboardEntryId from each group? – kunaguvarun Mar 27 '16 at 12:25
Instead of SelectMany just use the following "Select(c=> c.Max(x=> x.DashboardEntryId))" – Ali Hajahmed Mar 27 '16 at 13:48
Thank you. I came across this http://stackoverflow.com/questions/470440/how-to-select-only-the-records-with-the-highest-date-in-linq which also seems to solve the problem – kunaguvarun Mar 27 '16 at 13:52

LINQ EF Grouping and Include exception

1 Answers1