实体框架Lambda表达式获取特定列

Question

I have the following query but it's throwing error:

Cannot implicitly convert system.collections.generics.lists <> to system.collections.generics.ienumerable

The query:

public IEnumerable<ApplicationUser> GetUsersByRole(string roleName)
{
    var role = _context.Roles.FirstOrDefault(r => r.Name == roleName);

    return _context.Users
             .Where(u => u.Roles.Any(r => r.RoleId == role.Id))
             .Select(u => new ApplicationUser { Id = u.Id, FullName = u.FullName })
             .ToList();
}

In my application user class I have the Fullname property defined as follows:

public class ApplicationUser : IdentityUser
{
    public string FirstName { get; set; }
    public string LastName { get; set; }

    public string FullName
    {
        get {  return string.Format("{0} {1}", FirstName, LastName); }
    }
}

I also get error

property Indexer ApplicationUser.Fullname cannot be assigned to -- it is read only

Is there any way to keep the fullname property read only without adding a setter?

Answer 1

You're projecting into an anonymous type. You would have to use

.Select(u => new ApplicationUser { Id = u.Id, Name = u.UserName}).ToList();

To return an IEnumerable<ApplicationUser>