CODEWITHSUNDEEP
c#asp.net-mvclambda
Kamil Gonca
Kamil Gonca

Reputation: 11

c# lambda expression error...this dictionary requires a model item of type

When I change query I got an error. Could you please help?

    public ActionResult Index(int? id)
    {
        Models.MyProjectEntities entity = new Models.MyProjectEntities();

         // NORMAL QUERY, NO PROBLEM
         //var Messages = entity.Message.Where(x => x.Active);

         // JOINED QUERY, GENERATES ERROR
         var Messages = entity.Message.Join(entity.Categories, 
                            m => m.CategoriID,
                            k => k.CategoriID,
                            (m, k) => new { Message = m, Categories = k })
                            .Where(x => x.Message.Active);


        return View(Messages);
    }

Here is aspx file first line

<%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<IEnumerable<MyProject.Models.Message>>" %>

Here is the Error

The model item passed into the dictionary is of type 'System.Data.Objects.ObjectQuery`1[<>f__AnonymousType7`2[MyProject.Models.Message,MyProject.Models.Categories]]', but this dictionary requires a model item of type 'System.Collections.Generic.IEnumerable`1[MyProject.Models.Message]'.

Upvotes: 1

Views: 449

Answers (3)

maxlego
maxlego

Reputation: 4914

public ActionResult Index(int? id)
{
    Models.MyProjectEntities entity = new Models.MyProjectEntities();

     // NORMAL QUERY, NO PROBLEM
     //var Messages = entity.Message.Where(x => x.Active);

     // JOINED QUERY, GENERATES ERROR
     var Messages = entity.Message.Join(entity.Categories, 
                        m => m.CategoriID,
                        k => k.CategoriID,
                        (m, k) => new { Message = m, Categories = k })
                        .Where(x => x.Message.Active)
                        .Select(x => x.Message);


    return View(Messages);
}

or if you need categories as well, you should change views model type

EDIT:

public ActionResult Index(int? id)
{
    Models.MyProjectEntities entity = new Models.MyProjectEntities();

     // NORMAL QUERY, NO PROBLEM
     //var Messages = entity.Message.Where(x => x.Active);

     // JOINED QUERY, GENERATES ERROR
     var Messages = entity.Message.Join(entity.Categories, 
                        m => m.CategoriID,
                        k => k.CategoriID,
                        (m, k) => new MessageWithCategories { Message = m, Categories = k })
                        .Where(x => x.Message.Active);


    return View(Messages);
}

and model type should be MessageWithCategories (this class has to be created)

Upvotes: 0

TheRealTy
TheRealTy

Reputation: 2429

Because your joining an your creating an anonymous type, you need to do 

var Messages = entity.Message.Join(entity.Categories, 
    m => m.CategoriID,
    k => k.CategoriID,
    (m, k) => new { Message = m, Categories = k })
    .Where(x => x.Message.Active)
    .Select(x => new Message { ... .. ..  } );

Upvotes: 0

SLaks
SLaks

Reputation: 887453

Your view is declared as taking a set of Messages.
You're trying to pass it a set of anonymous types.

As the error clearly states, it doesn't fit.

Instead, you should create a class to hold the data from the join, then declare the view as taking a set of that class.
(Views cannot easily use anonymously typed models)

Upvotes: 2

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