EF Core 3.1 Fail to query on Json Serialized Object - sql-server

Question

I used json serialization to store list on ids in a field
Model:
public class Video
{
public int Id { get; set; }
public string Name { get; set; }
public virtual IList<int> AllRelatedIds { get; set; }
}
Context:
modelBuilder.Entity<Video>(entity =>
{
entity.Property(p => p.AllRelatedIds).HasConversion(
v => JsonConvert.SerializeObject(v, new JsonSerializerSettings { NullValueHandling = NullValueHandling.Ignore }),
v => JsonConvert.DeserializeObject<IList<int>>(v, new JsonSerializerSettings { NullValueHandling = NullValueHandling.Ignore })
);
});
It works fine, Adding, Editing, Deleting items is easy and in SQL Database it stores as json like
[11000,12000,13000]
Everything is fine BUT!! as soon as want to query on this list I get weird responses.
Where:
_context.Set<Video>().Where(t=>t.AllRelatedIds.contains(11000)) returns null however if I ask to return all AllRelatedIds items some records have 11000 value exp.
Count:
_context.Set<Video>().Count(t=>t.AllRelatedIds.contains(11000)) returns could not be translated. Either rewrite the query in a form that can be translated, or switch to client evaluation explicitly by inserting a call to either AsEnumerable(), AsAsyncEnumerable(), ToList(), or ToListAsync().
What's the matter with EF Core? I even tested t=>t.AllRelatedIds.ToList().contains(11000) but made no difference
What I should do? I don't want to have more tables, I used this methods hundreds of times but seems never queried on them.

Answer 1

The Json Serialization/Deserialization happens at application level. EF Core serializes the IList<int> object to value [11000,12000,13000] before sending it to database for storing, and deserializes the value [11000,12000,13000] to IList<int> object after retrieving it from the database. Nothing happens inside the database. Your database cannot operate on [11000,12000,13000] as a collection of number. To the database, its a single piece of data.
If you try the following queries -
var videos = _context.Set<Video>().ToList();
var video = _context.Set<Video>().FirstOrDefault(p=> p.Id == 2);
you'll get the expected result, EF Core is doing it's job perfectly.
The problem is, when you query something like -
_context.Set<Video>().Where(t=> t.AllRelatedIds.Contains(11000))
EF Core will fail to translate the t.AllRelatedIds.Contains(11000) part to SQL. EF Core can only serialize/deserialize it because you told it to (and how). But as I said above, your database cannot operate on [11000,12000,13000] as a collection of integer. So EF Core cannot translate the t.AllRelatedIds.Contains(11000) to anything meaningful to the database.
A solution will be to fetch the list of all videos, so that EF Core can deserialize the AllRelatedIds to IList<int>, then you can apply LINQ on it -
var allVideos = _context.Set<Video>().ToList();
var selectedVideos = allVideos.Where(t=> t.AllRelatedIds.Contains(11000)).ToList();
But isn't fetching ALL videos each time unnecessary/overkill or inefficient from performance perspective? Yes, of course. But as the comments implied, your database design/usage approach has some flaws.