LINQ query IN for array - linq

Question

I have the following model:
public class Device
{
//....
private ICollection<TagDevice> _tagDevices;
public virtual ICollection<TagDevice> TagDevices { get => _tagDevices ?? (_tagDevices = new List<TagDevice>()); protected set => _tagDevices = value; }
}
public class TagDevice
{
//....
public int TagId { get; set; }
}
I need to select all Devices, which has ALL TagIds from int array.
For example:
device1 has tags [1, 2, 3]
device2 has tags [2, 3, 4]
device3 has tags [3, 4, 5]
tagsApplied is [2,3]
result: returned device1 and device2
I try
query = query.Where(p => tagsApplied.Contains( )
but this method allows only one element, not element list
How to do it?

Answer 1

If i suppose the query is list of Device, change the contains function by Excepting List a from List b, like the following code :
IEnumerable<string> result = query
.Where(device => !tagApplied.Except(device.TagDevices.Select(t=>t.TagId)).Any())
.Select(x => x.Name);
Doc of Except
i hope that will help you fix the issue

Answer 2

Using LINQKit, you can create an extension method that creates an or expression testing against each member of an array:
public static class LinqKitExt { // using LINQKit
public static IQueryable<T> WhereAllIsContained<T,TKey>(this IQueryable<T> dbq, Expression<Func<T,IEnumerable<TKey>>> keyFne, IEnumerable<TKey> searchTerms) {
Expression<Func<T,bool>> pred = PredicateBuilder.New<T>();
foreach (var s in searchTerms)
pred = pred.And(a => keyFne.Invoke(a).Contains(s));
return dbq.Where(pred.Expand());
}
}
With this extension available, you can do
query = query.WhereAllIsContained(d => d.TagDevices.Select(td => td.TagId), tagsApplied);
I believe this should translate to SQL, but I don't have an EF Core model with a collection property to test.