Well, It's disappointing that .net DateTime doesn't work seamlessly with MongoDB driver. I believe support should be baked into driver.
Anyway you'll need to take couple of steps to make .net and MongoDB work together.
1) Decorate Date field in your interface with BsonDateTimeOptions attribute to tell MongoDB driver how to serialize .net DateTime. See BsonDateTimeOptions Documentation
Interface should looks like
public interface IProtein { int Count { get; set; } [BsonDateTimeOptions(Kind = DateTimeKind.Local)] DateTime Date { get; set; } }
2) In your GetProteinForDay function, replace
var collection = _db.GetCollection<IProtein>(DB_COLLECTION); var query = collection.AsQueryable<IProtein>() .Where(p => p.Date == day.Date);
with
var collection = db.GetCollection<Protein>(DB_COLLECTION); var query = collection.Find(p => p.Date == day);
Notice that, I have replaced interface IProtein with concrete implementation of interface, in my case Protein.
Update: Full program is attached as reference.
Source document:
{ _id: ObjectID('5964ebf315c46ab80b2c20f3), Count: 10, Date: '2017-07-11 00:00:00.000' }
Test Program:
using System; using MongoDB.Bson; using MongoDB.Bson.Serialization.Attributes; using MongoDB.Driver; namespace mongoT { public interface IProtein { ObjectId Id { get; set; } int Count { get; set; } [BsonDateTimeOptions(Kind = DateTimeKind.Local)] DateTime Date { get; set; } } public class Protein : IProtein { public ObjectId Id { get; set; } public int Count { get; set; } public DateTime Date { get; set; } public override string ToString() { return $"{nameof(Id)}: {Id}, {nameof(Count)}: {Count}, {nameof(Date)}: {Date}"; } } class Program { private static string DB = "ProteinsDB"; private static string COLLECTION = "Proteins"; static void Main(string[] args) { var result = GetProteinForDay(DateTime.Now.Date); Console.WriteLine(result); } public static IProtein GetProteinForDay(DateTime day) { var client = new MongoClient(); var db = client.GetDatabase(DB); var collection = db.GetCollection<Protein>(COLLECTION); var query = collection.Find(p => p.Date == day.Date); var protein = query.FirstOrDefault(); return protein; } } }
