see snippet below (done using LINQPad)
void Main()
{
var client = new MongoClient("mongodb://localhost:27017");
var database = client.GetDatabase("test");
var collectionEmpInfo = database.GetCollection<Employee>("Employee");
Employee EmpInfo = new Employee
{
EmpID = "103",
EmpName = "John",
CreatedAt = DateTime.Now,
EmpMobile = new List<Mobile>
{
new Mobile{ MobNumber = "55566610", IsPreferred = true, MobID = ObjectId.GenerateNewId() },
new Mobile{ MobNumber = "55566611", IsPreferred = false, MobID = ObjectId.GenerateNewId() },
}
};
var filterDef = new FilterDefinitionBuilder<Employee>();
var filter = filterDef.In(x=>x.EmpID , new[]{"101","102"});
filter.Dump();
var empList = collectionEmpInfo.Find(filter).ToList();
empList.Dump();
}
public class Employee
{
public ObjectId Id { get; set; }
public string EmpID { get; set; }
public string EmpName { get; set; }
public List<Mobile> EmpMobile { get; set; }
public DateTime CreatedAt { get; set; }
}
public class Mobile
{
public ObjectId MobID { get; set; }
public string MobNumber { get; set; }
public bool IsPreferred { get; set; }
}
and a screenshot of the results

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