Make good LINQ query with string[] - asp.net-mvc

Question

I have some problems with LINQ and maby someone got answers
string[] roleNames = Roles.GetRolesForUser(currentUserName);
result = context.MenuRoles.Select(mr => new MenuGenerateViewModel
{
MenuID = mr.MenuID,
MenuNazwa = mr.Menu.MenuNazwa,
MenuKolejnosc = mr.Menu.MenuKolejnosc,
MenuStyl = mr.Menu.MenuStyl,
MenuParentID = mr.Menu.MenuParentID,
MenuActive = mr.Menu.MenuActive,
MenuActionName = mr.Menu.MenuAction.MenuActionName,
MenuControlName = mr.Menu.MenuControl.MenuControlName,
RoleName = mr.Role.RoleName,
RoleID = mr.RoleID,
MenuID = mr.MenuID
})
.Where(mr => mr.MenuActive == true)
.ToList();
How to take only compare string[] roleNames and return only if match. Problem alwais is when user is in the 2 or more roles.
Tx for answers

Answer 1

If I understand what you are asking for, add a second condition to your Where clause:
.Where(mr => mr.MenuActive && roleNames.Contains(mr.Role.RoleName))

Answer 2

You would be better off switching round your Where clause and Select for the simple reason that then you will not be retrieving from the database records which are not required.
result = context.MenuRoles.Where(mr => mr.MenuActive
&& roleNames.Contains(mr.Role.RoleName))
.Select(mr => ... )
.ToList();
This will generate a sql which only selects the necessary records, instead of selecting the whole lot and then filtering it. Try it and watch SQL profiler to see the difference (useful skill in any case when using EF)

Answer 3

With the help of brilliant people here, reached the target.
string[] roleNames = Roles.GetRolesForUser(currentUserName);
result = context.MenuRoles
.Where(mr => mr.Menu.MenuActive && roleNames.Contains(mr.Role.RoleName))
.Select(mr => new MenuGenerateViewModel
{
MenuID = mr.MenuID,
MenuNazwa = mr.Menu.MenuNazwa,
MenuKolejnosc = mr.Menu.MenuKolejnosc,
MenuStyl = mr.Menu.MenuStyl,
MenuParentID = mr.Menu.MenuParentID,
MenuActive = mr.Menu.MenuActive,
MenuActionName = mr.Menu.MenuAction.MenuActionName,
MenuControlName = mr.Menu.MenuControl.MenuControlName,
RoleName = mr.Role.RoleName
})
.ToList();
var userresult = context.MenuUsers
.Where(mr => mr.Menu.MenuActive && mr.User.Username == currentUserName)
.Select(mr => new MenuGenerateViewModel
{
MenuID = mr.MenuID,
MenuNazwa = mr.Menu.MenuNazwa,
MenuKolejnosc = mr.Menu.MenuKolejnosc,
MenuStyl = mr.Menu.MenuStyl,
MenuParentID = mr.Menu.MenuParentID,
MenuActive = mr.Menu.MenuActive,
MenuActionName = mr.Menu.MenuAction.MenuActionName,
MenuControlName = mr.Menu.MenuControl.MenuControlName,
Username = mr.User.Username
})
.ToList();
Here, gets all the menu to which you have the right, both through group membership and assigned directly to the menu itself.
// Kick all duplicates
var noduplicates = result.Concat(userresult)
.Distinct(new RoleMenuGenerateComparer());
Because usually we do not want duplicates in the menu so we remove them. For this to work properly we need to implement IEqualityComparer (U can read about this little bit up)
public class RoleMenuGenerateComparer : IEqualityComparer<MenuGenerateViewModel>
{
public bool Equals(MenuGenerateViewModel x, MenuGenerateViewModel y)
{
//Check whether the compared objects reference the same data.
if (Object.ReferenceEquals(x, y)) return true;
//Check whether any of the compared objects is null.
if (Object.ReferenceEquals(x, null) || Object.ReferenceEquals(y, null))
return false;
//Check whether the products' properties are equal.
return x.MenuNazwa == y.MenuNazwa && x.MenuID == y.MenuID;
}
public int GetHashCode(MenuGenerateViewModel menuGenerateViewModel)
{
if (Object.ReferenceEquals(menuGenerateViewModel, null)) return 0;
int hashMenuName = menuGenerateViewModel.MenuNazwa == null ? 0 : menuGenerateViewModel.MenuNazwa.GetHashCode();
int hashMenuID = menuGenerateViewModel.MenuID == null ? 0 : menuGenerateViewModel.MenuID.GetHashCode();
return hashMenuName ^ hashMenuID;
}
}
Of course I believe that you can optimize this code, but for the moment I have something like this.
Tx all for help.