LINQ contains exactly matching

We have the following class structure and want to query all user who has at least all roles or more from the mustHaveRole Queryparameter.
If someone has a good idea that would be cool :-)

public class User
{
public Guid UserId { get; set; }
public string Username { get; set; }
public ICollection<UserRole> Roles { get; set; } = new HashSet<UserRole>();
}

public class UserRole
{
public virtual User User { get; set; }
public Guid UserId { get; set; }

public virtual Role Role { get; set; }
public Guid RoleId { get; set; }
}

public class Role
{
public Guid RoleId { get; set; }
public string RoleName { get; set; }
public ICollection<User> Users { get; set; } = new HashSet<User>();
}

public class QueryHandler
{
readonly List<User> Users = new List<User>();

public IEnumerable<User> Handle(List<Guid> musthaveRoles)
{
var queryResult =
from u in Users
from r in u.Roles
where musthaveRoles.Contains(r.RoleId) //ContainsAllExact and not has one of the roles???
select u;

return queryResult;
}
}


2 Answers
2

If you need an exact match you can use SequenceEqual method. To make it work you need to order your ids

SequenceEqual

ids

public IEnumerable<User> Handle(List<Guid> musthaveRoles)
{
var queryResult = Users.Where(
u => u.Roles.Select(r => r.RoleId).OrderBy(id => id)
.SequenceEqual(musthaveRoles.OrderBy(id => id)));

return queryResult;
}


This query will return only users who have exact same roles you expect and will filter out users who have more roles

the users with more roles should be also in the queryResult

You can use Intersect method:

Intersect

public IEnumerable<User> Handle(List<Guid> musthaveRoles)
{
var queryResult = Users.Where(u => u.Roles.Select(r => r.RoleId)
.Intersect(musthaveRoles).Count() == musthaveRoles.Count);
return queryResult;
}


Check a demo

I think what you are looking for is this:

var queryResult = Users.Where(x => musthaveRoles.All(y => x.Roles.Select(z => z.RoleId).Contains(y)));

// or this way
var queryResult1 = Users.Where(x => !musthaveRoles.Except(x.Roles.Select(y => y.RoleId)).Any());


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