How can I convert mongo script to pure C# code by using native MongoDB.Driver?

Question

How can I convert below mongodb shell script to C# by using "MongoDB.Driver" ? the script below is working perfect in local. There is no issue in script. But if I publish it as Azure func. There is permission issue for "eval "operator. So I decided to rewrite above script as Native C# by using MongoDb.Driver.I developed below code, but "eval" didn't work and throwed error while running in Azure function: "Command eval failed: Command is not supported. ". I decided convert to pure C# code.How can I do That?

    Date.prototype.addDays = function(h) {    
   this.setTime(this.getTime() + (h*60*60*1000*24)); 
   return this;   
} 

var beforeDate = (new Date()).addDays(-7);
var totalDeleted = 0;

do
{

    var ids = db.klm
        .find({
            CreatedDate: {$lt: beforeDate},
            xyz: {$eq: null},
            abc: {$eq: null},
            Items: { $size: 0 }
        })
        .limit(100)
        .map(function (doc) { return doc._id; });

    totalDeleted += ids.length;

    //db.klm.remove({"_id": { "$in": ids }});

} while (ids.length > 0);

print("Deleted " + totalDeleted + " rows before " + beforeDate);

Answer 1

the following will delete everything with the matching filter. it does not delete in batches of 100s as your shell code which would be less efficient. the following only issues a single mongodb query which would take care of deleting all matching records.

var beforeDate = DateTime.UtcNow.AddDays(-7);

var filter = Builders<klm>.Filter
                          .Where(k =>
                                 k.createdDate < beforeDate &&
                                 k.abc == null &&
                                 k.xyz == null &&
                                 (k.items.Count() == 0 || k.items == null));

var result = collection.DeleteMany(filter);

Console.WriteLine($"Deleted {result.DeletedCount} documents created before {beforeDate.ToShortDateString()}");

update: the following will result in 2 queries for each batch of 100 records.

var beforeDate = DateTime.UtcNow.AddDays(-7);
var totalDeleted = 0;
var ids = new List<ObjectId>();

do
{
    ids = collection.Find(k =>
                          k.createdDate < beforeDate &&
                          k.abc == null &&
                          k.xyz == null &&
                         (k.items.Count() == 0 || k.items == null))
                    .Limit(100)
                    .Project(k => k.Id)
                    .ToList();

    if (ids.Any())
    {
        collection.DeleteMany(k => ids.Contains(k.Id));
        totalDeleted += ids.Count();
    }               

} while (ids.Any());

Console.WriteLine($"Deleted {totalDeleted} documents created before {beforeDate.ToShortDateString()}");
Console.ReadLine();