CODEWITHSUNDEEP
asp.net-mvcasp.net-mvc-3
Sugar Bowl
Sugar Bowl

Reputation: 1792

How to pass collection of anonymous objects from controller to view

I am new to MVC, so please excuse me if my question sounds silly or too simple. I am using Entity Data Model for database access. So in my Models folder, I have added an EDMX file and I can access the model classes from my controllers and strongly typed views. The problem arises when I access more than one table in my controller e.g.

If I have following tables in my DB : 

 Departments(DepartmentID, DepartmentName, DepartmentPhone)
 Insurances(InsuranceID, InsuranceName, InsuranceAddress)
 Employees(EmployeeID, EmpFName, EmpLName, DepartmentID, InsuranceID)

And I want to display a list of Employees with their department and insurance information.

In my Controller's Action Method I access the DB using EDM and get the information in an anonymous type:

 using (var context = new MyEntities())
        {
            var model = (from d in context.Departments
                         join e in context.Employees on d.DepartmentID equals e.DepartmentID
                         join I in context.Insurances on I.InsuranceID equals e.InsuranceID

                         select new
                         {
                             DepartmentID = d.DepartmentID,
                             EmployeeID= e.EmployeeID,
                             EmpFName= e.EmpFName,
                             EmpLName= e.EmpLName,
                             DepartmentName= d.DepartmentName,
                             InsuranceName= I.InsuranceName

                         }).ToList();

            return View(model);
        }

I don't have a class of this anonymous type in my Model folder so I can't create a strongly typed view. So what is the best way to pass this list to the View?. Using viewbag will be an overkill if the collection is too large. Creating a new Model for this anonymous class doesn't sound right as it needs to be updated all the time if I change my selection in Controllers Action Method.

All suggestions are welcomed. I tried looking through other questions on SO but couldn't find anything relevant.

Thanks.

Upvotes: 1

Views: 1506

Answers (3)

Darin Dimitrov
Darin Dimitrov

Reputation: 1039448

I don't have a class of this anonymous type in my Model folder so I can't create a strongly typed view

Right click on your project, Add New Class ... and now you have a type in your Model folder. This is the way to go in ASP.NET MVC => view models.

And then obviously you pass this type to your view:

select new MyViewModel
{
    DepartmentID = d.DepartmentID,
    EmployeeID = e.EmployeeID,
    EmpFName = e.EmpFName,
    EmpLName = e.EmpLName,
    DepartmentName = d.DepartmentName,
    InsuranceName = I.InsuranceName
}).ToList();

And of course now your view becomes strongly typed to this view model:

@model IEnumerable<MyViewModel>
...

Upvotes: 2

Alexander Beletsky
Alexander Beletsky

Reputation: 19841

dynamic type is your friend.

You can declare your view as loosely typed, having a dynamic as your model

@model dynamic

You will access model properties as you do in strongly typed view

<h1>Model.DepartmentId</h1> - <h2>Model.DepartmentName</h2>
<span>Model.EmployeeId</span>

The problem thought, that dynamics contains internal properties, if you are using MVC2 you need a little trick to make it work. But seems for MVC3 and higher, it's not longer required.

Upvotes: 0

Dai
Dai

Reputation: 155658

I'm afraid that predefined strongly-typed ViewModels are the way to go. It is a pain to have to update seemingly duplicate code in multiple places but in my experience it's only a problem for smaller projects. As the project grows you begin to see differences between database model objects (entities) and the viewmodels passed to your views, such as Validation and processing attributes and view-specific data, and when you get to that point you begin to prefer having separate Entity and ViewModel definitions.

However, back on-topic: an alternative solution to your problem is to use reflection to convert an anonymous type into a Dictionary<String,Object> object. Note that ASP.NET MVC does this for converting new { foo = "bar" }-syntax expressions into dictionaries for Route Values and HTML attributes already. Performance is acceptable, but don't try to do it for 10,000 objects for a single HTTP request otherwise you might get bogged down.

Here's what the code for that would look like:

Object anonymousType = new { whatever = "foo" };
Dictionary<String,Object> dict = new Dictionary<String,Object>();

foreach (PropertyDescriptor descriptor in TypeDescriptor.GetProperties(anonymousType )) {
    Object value = descriptor.GetValue(anonymousType );
    dict.Add( descriptor.Name, value );
}

Of course this means that your Views won't benefit from compile-time type-checking and you'll have to maintain a documented list of dictionary keys (assuming you aren't iterating over keys in your view).

I'll note that I am surprised Microsoft didn't make anonymous types automatically implement IDictionary because it seems natural.

Upvotes: 0

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