How can we get list of two column say firstname and lastname from customer table in mvc using linq query

Question

Customer Table

Every time I run this I get an error:

Unable to cast object of type 'System.Collections.Generic.List1[<>f__AnonymousType1 2[System.String,System.String]]' to type 'System.Collections.Generic.IEnumerable1[CRUD__MVC.Models.Customer]

Code:

public ActionResult FirstLastName()
{
    return View(Name()); 
}

IEnumerable<Customer>Name()   
{
    using (AdventureWorksLTDataContext db = new AdventureWorksLTDataContext())
    {
        return (IEnumerable<Customer>)db.Customers.Select(c => new { FirstName = c.FirstName, LastName = c.LastName }).ToList();
    }
}

Answer 1

You can create a new Model class which will consist of your selected data from the Customer class:

public class GetCustomerInformation
{
 public string FirstName {get;set;}
 public string LastName {get;set;}
}

And you can then Select the required like this:

IEnumerable<GetCustomerInformation>Name()   
{
    using (AdventureWorksLTDataContext db = new AdventureWorksLTDataContext())
    {
        return (IEnumerable<GetCustomerInformation>)db.Customers.Select(c => new GetCustomerInformation { FirstName = c.FirstName, LastName = c.LastName });
    }
}

I have made a sample here for you reference. I am manually adding data to the list and then selecting what is required: https://dotnetfiddle.net/CW9APV

Now since you are querying the DB to get your data, you can't create entities as part of a query. Entities can be created outside of queries and inserted into the data store using a DataContext . You can then retrieve them using queries.

So a workaround would be:

Generate a class that derives from your LINQ to SQL class:

internal class CustomerView: Customer { }

Write your query in this way:

IEnumerable<Customer> Name()   
{
    using (AdventureWorksLTDataContext db = new AdventureWorksLTDataContext())
    {
        var query= db.Customers.Select(c => new CustomerView { FirstName = c.FirstName, LastName = c.LastName }).ToList();
        //Cast it back to Customer
        return (query.Cast<Customer>())
    }
}