[BUG] Predicates with arguments do not work with DeleteMany

Version LiteDB 5.0.1, net45, Windows 10

Describe the bug Predicates with arguments do not work with collection’s DeleteMany in LiteDB v5.0.1

Code to Reproduce Example:

• create BsonExpression predicate with an argument
• use it with DeleteMany, the expected document is not deleted
• the same predicate works fine with FindOne
• DeleteMany still works with the similar predicate without arguments

using (var db = new LiteDatabase(":memory:"))
{
    var c1 = db.GetCollection("Test");

    var d1 = new BsonDocument() { ["_id"] = 1, ["p1"] = 1 };
    c1.Insert(d1);
    Console.WriteLine($"count {c1.Count()}");

    {
        // try BsonExpression predicate with argument - not deleted
        var e1 = BsonExpression.Create("$._id = @0", 1);
        var r1 = c1.DeleteMany(e1);
        Console.WriteLine($"1. deleted {r1}");

        // the same BsonExpression predicate works fine in FindOne
        var r = c1.FindOne(e1);
        Console.WriteLine($"document: {r}");
    }

    {
        // try BsonExpression predicate hardcoded - deleted
        var e1 = BsonExpression.Create("$._id = 1");
        var r1 = c1.DeleteMany(e1);
        Console.WriteLine($"2. deleted {r1}");

        // double check - Count = 0
        Console.WriteLine($"count {c1.Count()}");
    }
}

Output:

count 1
1. deleted 0
document: {"_id":1,"p1":1}
2. deleted 1
count 0

[mbdavid]

This will be very important when LiteDB will support some “T-SQL-Like” language for store procedures and triggers (is on my roadmap)

[qart2003]

Hi @mbdavid , this method is from DAL (repo) implemented in linq way Doesnot work public void DeleteByIds(IEnumerable<int> ids) { Collection.DeleteMany(v => ids.ToList().IndexOf(v.Id) > -1); }

I’m thinking it’s a bug but not sure (may ne should not be implemented on the db level) I had something like this and my solution was `public static class RepoBasicExt { public static IEnumerable<T> FindWithBug<T>(this RepoBasic repo, ILiteCollection<T> Collection, Expression<Func<T, bool>> func) { try { return Collection.Find(func); } catch (NotSupportedException ex) { var internalFunc = func.Compile(); return Collection.FindAll().Where(internalFunc); } } //not good if we talk about performance, may be make sense to think about it on the “db level” public static IEnumerable<T> Find<T>(this RepoBasic repo, ILiteCollection<T> Collection, Expression<Func<T, bool>> func) => Collection.FindAll().Where(func.Compile());

}`