将表联接结果传递给视图？

Question

I have the following ASP.Net MVC controller action which joins 2 tables:-

public ActionResult PersonNotes()
{
    var model = db.Notes
        .Join(db.People, p => p.NotesListId, n => n.NotesListId, 
            ((note, person) => new { note, person })).ToList();
    return View(model);
}

And in my view I have the following model declaration:-

@model IEnumerable<Tuple<Models.Note, Models.Person>>

I get the following error:-

System.InvalidOperationException: The model item passed into the dictionary is of type 'System.Collections.Generic.List`1[<>f__AnonymousTypef`2[Models.Note,Models.Person]]', but this dictionary requires a model item of type System.Collections.Generic.IEnumerable`1[System.Tuple`2[Models.Note,Models.Person]]'.

I realise that I can just use a ViewModel and a Select() within my join, but it would far more convenient to just have access to all items without having to create a ViewModel.

What is the correct declaration in my view, or is what I am trying to achieve not possible this way?

Answer 1

You are returning an anonymous object and your view wants a model with a Tuple . The anonymous type is generated by the compiler and is not available at the source code level.

Try changing your statement to create an IEnumerable<Tuple<Models.Note, Models.Person>> with Tuple.Create :

var model = db.Notes
    .Join(db.People, p => p.NotesListId, n => n.NotesListId, 
        ((note, person) => Tuple.Create(note, person))).ToList();

See Tuple.Create .

If you are using Linq to Entities or Entity Framework then you will need to either iterate the IQueryable into a Tuple or use a class .

var model = db.Notes
    .Join(db.People, p => p.NotesListId, n => n.NotesListId, 
        ((note, person) => new { note, person }))
    .AsEnumerable()
    .Select(x => Tuple.Create(x.note, x.person))
    .ToList();

Or

Create a class to hold the Person and Note .

public class PersonNote
{
    public Person Person { get; set; }
    public Note Note { get; set; }
}

Change the statement to use the new PersonNote .

var model = db.Notes
    .Join(db.People, p => p.NotesListId, n => n.NotesListId, 
        ((note, person) => new PersonNote { Note = note, Person = person }))
    .ToList();

Change the model.

@model IEnumerable<PersonNote>