ASP.NET MVC error cannot convert lambda expression to type 'string' because it is not a delegate type

Question

View - MovieForm.cshtml:

<div class="form-group">
    @Html.LabelFor(m => m.Movie.GenreId)
    @Html.DropDownList(m => m.Movie.GenreId, new SelectList(Model.Genres, "Id", "Name"), "Select a Genre", new { @class = "form-control" })
</div>

View model - MovieFormViewModel:

public class MovieFormViewModel
{
    public IEnumerable<Genre> Genres { get; set; }
    public Movies Movie { get; set; }  
}

Model classes:

public class Movies
{
    public int Id { get; set; }
    [Required]
    [StringLength(255)]
    public string Name { get; set; }
    [Required]
    public Genre Genre { get; set; }
    public int GenreId { get; set; }
    public DateTime ReleaseDate { get; set; }
    public DateTime DateAdded { get; set; }
    public int NumberInStock { get; set; }
}

public class Genre
{
    public int Id { get; set; }
    [Required]
    [StringLength(255)]
    public string Name { get; set; }
}

Controller - MoviesController:

public ActionResult NewMovie(int id)
{
    var movie = _context.Movies.SingleOrDefault(m => m.Id == id);
        
    var viewModel = new MovieFormViewModel
        {
            Movie = movie,
            Genres = _context.Genres.ToList()
    };

    return View("MovieForm", viewModel);
}

My DbSet is:

public DbSet<Genre> Genres { get; set; }

The only problem I have is in my view (MovieForm.cshtml).

This line of markup

@Html.LabelFor(m => m.Movie.GenreId)

doesn't cause any errors, however this

@Html.DropDownList(m => m.Movie.GenreId, new SelectList(Model.Genres, "Id", "Name"), "Select a Genre", new { @class = "form-control" })

throws an error

Cannot convert lambda expression to type 'string' because it is not a delegate type.

This error is in m.Movie.GenreId which was was working fine in the previous line.

Answer 1

Change DropDownList to DropDownListFor.