MongoDB C# Why can't you use DateTime.Date with IQueryable?

Question

I have method set up in my MongoDB DAL class.

public IQueryable<MyModel> Retrieve(Expression<Func<MyModel, bool>> expression) 
{
    if (!BsonClassMap.IsClassMapRegistered(typeof(MyModel)))
    {
        DoMapping();
    }

    var client = new MongoClient(MongoConnectionString);
    var database = client.GetDatabase("DatabaseName");
    var documents = database.GetCollection<MyModel>("MyModelTable");

    return documents.AsQueryable<MyModel>().Where(expression);
}

I want to do something simple like

var result = Retrieve(a => a.SomeDateProperty.Date >= startDate && a.SomeDateProperty.Date <= endDate);

However, every time I try, I get an error stating:

An exception of type 'System.InvalidOperationException' occurred in MongoDB.Driver.dll but was not handled in user code

Additional information: {document}{SomeDateProperty}.Date is not supported.

I am using the official C# driver version 2.2.4.26.

Is there a way to query on just the date? I've seen posts about using DbFunctions.Truncate, but that is in the EntityFramework libraries, which I would like to stay away from.

Answer 1

I had same problem with using Date and i used:

Idea is to use two borders (DateTime.Date is also DateTime but with 0 hours, 0 minutes... and second is next day also with 0 hours, 0 minutes...).

DateTime currentDayStart = DateTime.Now.Date;
DateTime currentDayEnds  = DateTime.Now.Date.AddDays(1);

var result = Retrieve(a => a.SomeDateProperty >= currentDayStart && a.SomeDateProperty < currentDayEnds);

And it works well for me.