In my Azure Function I did a WEBSITE_TIME_ZONE configuration as Europe/London. In my base class I’m creating Date Objects as below:

public class BaseService
{
    public DateTime Yesterday { get; set; }
    public DateTime Today { get; set; }

    public BaseService()
    {
        SeedData();
    }

    private void SeedData()
    {
        // Configure Processing Dates
        bool isManul = Environment.GetEnvironmentVariable(ConfigConstants.IsManual).ExactBool();            
        DateTime processingDate = isManul ? Environment.GetEnvironmentVariable(ConfigConstants.ManualDate).ExactDateTime() : DateTime.Now;

        Yesterday = processingDate.AddDays(-1);
        Today = processingDate;
    }
}

In another service that is inherited by this base class, I’m using these date objects to query MongoDB

public class MyService : BaseService
{
   var filter = fd.Gte(FieldConstants.CreatedDate, Yesterday.Date)
     & fd.Lt(FieldConstants.CreatedDate, Today.Date);
   ////
}

But, what I observed in MongoDB log is (Assuming Today is “27-jun-2024”) that the Query utilized wrong Date with TimeZone issue:

Expected

"query": {
    "processedDate": {
       "$lt": {
       "$date": "2024-06-26T00:00:00Z"
     }
   }
 },

Actual

"query": {
    "processedDate": {
       "$lt": {
       "$date": "2024-06-25T23:00:00Z"
     }
   }
 },