How to filter by a TimeSpan field stored as string using mongodb c# driver?

Question

I have a mongodb collection with a field that stores time in string format. In my C# code, the model has a property of type TimeStamp:

public TimeSpan StartTime { get; set; }

I need a query to get all documents where StartTime is greater than UtcNow. Something like:

var now = new TimeSpan(DateTime.UtcNow.Hour, DateTime.UtcNow.Minute, DateTime.UtcNow.Second);
...
...
var docs = db.GetCollection<DocDataModel>("docs")
             .AsQueryable()
             .Where(e => e.StartTime > now)

But I get an InvalidOperationException with message: Where(({document}{StartTime} > 12:04:52))) is not supported.

Is there any way to write this query properly?

Answer 1

Convert the StartTime and now variable to long using TimeSpan.Ticks

var now = new TimeSpan(DateTime.UtcNow.Hour, DateTime.UtcNow.Minute, DateTime.UtcNow.Second).Ticks;
...
...
var docs = db.GetCollection<DocDataModel>("docs")
             .AsQueryable()
             .Where(e => e.StartTime.Ticks > now)